the influence of the site factors wind exposure and slope

THE INFLUENCE OF THE SITE FACTOR WIND

EXPOSURE ON WOOD QUALITY

Final Report: Project FAIR CT 98 5038

Period: 5.10.1998 – 4.10.2000

A European Commission funded Training Grant with Assistance from

the Forestry Commission, James Jones and Sons Ltd., and the Building

Research Establishment.

Franka Brüchert Forestry Commission, Northern Research Station

Roslin, Midlothian EH25 9SY, Scotland

Table of contents

1 Objectives: ......................................................................................................................................... 7

2 Working Programme: ........................................................................................................................ 8

3 Methodology...................................................................................................................................... 9

3.1 Stand and tree selection: ................................................................................................................ 9

3.1.1 Stand selection ....................................................................................................................... 9

3.1.2 Tree selection......................................................................................................................... 9

3.2 Sampling strategy ........................................................................................................................ 11

3.3 Tree characterisation.................................................................................................................... 12

3.3.1 Spatial competition and tree morphometry.......................................................................... 12

3.3.2 The mechanical properties of the standing stem.................................................................. 14

3.4 Internal stem structure ................................................................................................................. 15

3.4.1 Density of fresh disc material .............................................................................................. 15

3.4.2 Density of air-dry disc material: .......................................................................................... 15

3.4.3 Ring width............................................................................................................................ 15

3.5 Roundwood and saw log assessment ........................................................................................... 16

3.5.1 Branchiness.......................................................................................................................... 17

3.5.2 Ring width............................................................................................................................ 17

3.5.3 Spiral grain........................................................................................................................... 17

3.5.4 Position of the pith............................................................................................................... 18

3.5.5 Log taper .............................................................................................................................. 18

3.6 End-product ................................................................................................................................. 18

3.6.1 Machine stress grading ........................................................................................................ 19

3.6.2 Kiln drying........................................................................................................................... 20

3.6.3 Dimensional stability ........................................................................................................... 21

3.6.4 Modulus of Elasticity, Modulus of Rupture......................................................................... 21

3.6.5 Juvenile wood ...................................................................................................................... 21

3.6.6 Density ................................................................................................................................. 22

3.6.7 Knottiness ............................................................................................................................ 22

3.6.8 Grain angle........................................................................................................................... 23

3.6.9 Compression wood .............................................................................................................. 23

4 Results.............................................................................................................................................. 25

4.1 Selection and characterisation of the site. General stand characteristics ..................................... 25

4.2 Characterisation of the sample trees: ........................................................................................... 26

4.2.1 Size and shape of the sample trees....................................................................................... 26

4.2.2 Straightness score ................................................................................................................ 29

3

Table of content (cont.)

4.2.3 Mechanical properties of the standing trees......................................................................... 30

4.2.3.1 Static pulling tests, structural Young’s modulus (MOEstruct) ....................................... 30

4.2.3.2 Dynamic pulling tests, swaying frequency .................................................................. 34

4.2.4 Internal stem structure ......................................................................................................... 37

4.2.4.1 Density of the fresh discs ............................................................................................. 37

4.2.4.2 Density of air dry discs ................................................................................................ 38

4.2.4.3 Radial increment .......................................................................................................... 39

4.3 Roundwood and saw log assessment ........................................................................................... 41

4.3.1 Branchiness.......................................................................................................................... 41

4.3.2 Ring width............................................................................................................................ 43

4.3.3 Spiral grain........................................................................................................................... 45

4.3.4 Position of the pith (log eccentricity)................................................................................... 47

4.3.5 Log taper .............................................................................................................................. 48

4.3.6 Log ovality........................................................................................................................... 50

4.3.7 Proportion of juvenile wood ................................................................................................ 52

4.3.8 Log classification according to ENV 1927-1....................................................................... 53

4.4 End product, quality of battens .................................................................................................... 55

4.4.1 Stress grading....................................................................................................................... 55

4.4.2 Modulus of elasticity, modulus of rupture ........................................................................... 57

4.4.3 Distortion ............................................................................................................................. 61

4.4.3.1 Twist ............................................................................................................................ 61

4.4.3.2 Bow.............................................................................................................................. 63

4.4.3.3 Spring........................................................................................................................... 64

4.4.4 Structural characteristics of the battens ............................................................................... 66

4.4.4.1 Density ......................................................................................................................... 66

4.4.4.2 Juvenile wood .............................................................................................................. 67

4.4.4.3 Compression wood....................................................................................................... 68

4.4.4.4 Grain angle................................................................................................................... 69

4.4.4.5 Knottiness .................................................................................................................... 70

5 Summary.......................................................................................................................................... 72

6 References........................................................................................................................................ 74

4

Table of figures

Figure 1: Variation of the normalised bending moment of the sample trees ............................................. 9

Figure 2: Position of the measurement lines within the site in relation to the edge ................................ 10

Figure 3: Variation of bending moment of the sample trees with age ..................................................... 11

Figure 4: Sampling pattern of saw logs and stem discs ........................................................................... 11

Figure 5: triangle method to estimate crown projection area................................................................... 13

Figure 6: Set up for tree pulling and tree swaying experiments .............................................................. 14

Figure 7: Cutting scheme of logs............................................................................................................. 19

Figure 8: Types of distortion of sawn timber........................................................................................... 21

Figure 9: Setup of grain angle measurements on battens......................................................................... 23

Figure 10: Setup for measuring compression wood area........................................................................ 24

Figure 11: Variation of mean and standard deviation of dbh, height and height-to-diameter-ratio ........ 27

Figure 12: Variation of tree height and the height of the crown variables .............................................. 28

Figure 13: Variation of crown projection area and crown asymmetry .................................................... 29

Figure 14: Variation of the straightness score in relation to distance from the stand edge ..................... 30

Figure 15: Variation of the structural Young’s modulus within the tested lines ..................................... 31

Figure 16: Inter-tree variation of structural Young’s modulus for individual sampling trees ................. 32

Figure 17: Variation of structural Young’s modulus within the stem for individual sampling trees ...... 33

Figure 18: Distribution of the intra-tree heterogeneity of MOEstruct ....................................................... 34

Figure 19: Variation of strain at different stem heights due to tree swaying for an individual tree ........ 35

Figure 20: Variation of the swaying frequency and tree height............................................................... 35

Figure 21: Natural swaying frequency of the sample trees...................................................................... 36

Figure 22: Variation of the fresh density within the tested lines ............................................................. 37

Figure 23: Variation of the air-dry disc density within the tested lines ................................................... 39

Figure 24: Difference in radial increment in windward and leeward direction ....................................... 40

Figure 25: Variation of the diameter of the thickest branch per log ........................................................ 41

Figure 26: Percentage logs per grade - branchiness................................................................................. 42

Figure 27: Variation of mean ring width ................................................................................................. 44

Figure 28: percentage of logs per grade – ring width .............................................................................. 44

Figure 29: Variation of the spiral grain angle......................................................................................... 46

Figure 30: Percentage of logs per grade – according to spiral grain (butt logs only) .............................. 46

5

Table of figures (cont.)

Figure 31: Variation of log eccentricity................................................................................................... 47

Figure 32: Percentage of logs per grade due to eccentricity only............................................................ 48

Figure 33: Variation of the log taper........................................................................................................ 49

Figure 34: Percentage of logs per grade – log taper ................................................................................ 50

Figure 35: Variation of log ovality .......................................................................................................... 51

Figure 36: Variation of the proportion of juvenile wood......................................................................... 52

Figure 37: Results log grading – classification after ENV 1927-1 .......................................................... 53

Figure 38: Percentage of logs graded by the individual criteria .............................................................. 54

Figure 39: Variation of MOEmin of central positioned battens from the butt and the top log .................. 55

Figure 40: Distribution of battens qualifying for C24, C16, reject.......................................................... 56

Figure 41: Change in strength classification between grading specifications ......................................... 57

Figure 42: Variation of mean MOEstat ................................................................................................... 58

Figure 43: Variation of MOEstat for battens from the different positions ................................................ 59

Figure 44: Variation of MOR .................................................................................................................. 60

Figure 45: Variation of MOR (different positions within the stem) ........................................................ 60

Figure 46: Variation of twist.................................................................................................................... 62

Figure 47: Variation of bow..................................................................................................................... 63

Figure 48: Variation of spring ................................................................................................................. 65

Figure 49: Variation of air dry density (battens) ..................................................................................... 66

Figure 50: Variation of juvenile wood..................................................................................................... 67

Figure 51: Variation of the mean compression wood ratio...................................................................... 68

Figure 52: Variation of grain angle.......................................................................................................... 70

Figure 53: Variation of mean knot diameter............................................................................................ 70

Figure 54: Variation of knot area on batten surface ................................................................................ 71

6

Table of tables

Table 1: Selected limits for log assessment according to ENV 1927-1 (1998) ....................................... 17

Table 2: Drying schedule for kiln drying test battens.............................................................................. 20

Table 3: An abbreviated tariff of the Kilmichael site .............................................................................. 25

Table 4: Statistical model to predict MOEstruct from line and stem height............................................... 31

Table 5: Regression models of the relation between absolute stem height x and MOEstruct..................... 32

Table 6: Regression models of the relation between absolute stem height and fresh disc density.......... 38

Table 7: Statistical model to predict air-dry disc density from line and stem height............................... 38

Table 8: Regression models of the relation between absolute stem height and air-dry disc density ....... 39

1 Objectives:

The influence of wind loading on tree form effects fundamentally morphological, anatomical and

chemical modifications in wood formation, modifying cell size and shape, cell wall thickness,

microfibril angles and lignin content in the cell wall. These changes are manifest at a larger scale as

changes in wood density and ring width, the presence of reaction wood and growth stresses.

The overall objective of this project is to predict from stand characteristics and measurements on

individual trees the wood quality of timber produced from a wind-exposed stand and of the potential

end products. The high variability in properties of trees and wood indicates a great potential for

optimisation of timber production and utilisation. The project links forest production and sawmill

utilisation in order to deal with stands subjected to large mechanical impacts from wind. Investigations

on the effect of wind exposure and slope on tree form and mechanical properties of the entire stem will

enlarge the understanding of the abiotic risks to the stability of trees apart from the importance of the

root anchorage. This knowledge will be incorporated into existing stand stability models and will make

it possible to develop forest management options specifically for stand protection on windy or steep-

sloped sites.

The quality and the yield of timber produced from exposed plantations have been the subject of limited

research so far. Therefore the investigations on timber yield and quality will improve and adapt existing

timber processing procedures, in particular with respect to end-user specifications. This will allow a

more precise description of wood quality based on the special demands of the end-user.

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2 Working Programme:

The project considers four hierarchical levels to investigate the effect of wind on tree and timber quality.

The working programme was designed to follow the entire process from timber production to end

product in order to correlate the final timber quality assessment with the environmental conditions and

silvicultural treatment of the raw material (forest-wood-chain).

Level I. Forest : detailed description of the selected site in order to qualify and quantify the effects

of the environmental and silvicultural conditions on the trees

Level II. Tree: detailed description of each sample tree in order to understand the growth reaction

of the tree for the particular growth situation. The characterisation of each tree includes

its outer size and shape, its static and dynamic mechanical response to loads and

investigations on the internal distribution of selected wood properties

Level III. Round wood, saw logs: the description of each saw log will allow an assessment of the

quality of raw material, in order to link between the tree and the conversion into the final

product at the sawmill

Level IV. End-product: detailed measurements on the performance of final product with respect to

the end-user’s requirements will allow an assessment of the overall quality of raw wood

material from exposed sites, to validate existing yield and timber quality models and

allow advice on silvicultural treatment on exposed sites.

3 Methodology

3.1 Stand and tree selection :

3.1.1 Stand selection

The revised site selection protocol (progress report, 1999) altered the number of chosen sites from

4 to 1 site in order to keep as many site and stand characteristics such as elevation, aspect, slope,

temperature regime, microclimate and soil type constant. The site was described by

location

grid reference,

exposure, aspect, DAMS score (windiness score) (Quine & White, 1993)

planting year, planting density, silvicultural treatment,

top height, mean diameter, yield class (GYC) (Forestry Commission, 1991)

abbreviated tariff of 8 circular 0.01 ha plots measuring dbh of each tree above 7cm dbh and the height of the thickest tree in each plot

3.1.2 Tree selection

In total 60 trees were sampled from four lines parallel with the stand edge and at different

distances. Within a stand the mean wind speed decreases rapidly from the edge to the inner stand

(Peltola & Kellomaeki, 2000; Stacey et al., 1994) (Figure 1).

Figure 1: Variation of the normalised bending moment of the sample trees with distance from the stand edge for unthinned Sitka spruce YC10 with 1.7m initial spacing (after Stacey et al., 1994; Gardiner et al., 2000)

0

0.2

0.4

0.6

0.8

1

0 20 40 60 80 100

distance from edge [m]

norm

aliz

ed b

endi

ng m

omen

t [/]

21 years31 years41 years51 years

9

Distances from the edge to the mid-forest were chosen (later referred as line No 1, 2, 3, 4) representing

the varying wind exposure to the trees. Each line consists of three planting rows; the middle row

represents the exact distance in actual tree height(s). Figure 2 illustrates the positions of the lines used in

the experiments. An abbreviated tariff of 8 rectangular plots consisting of 12 trees each was untertaken

in order to characterise the mean dbh and top height of the selected lines. In each plot, the dbh of each

tree above 7cm dbh was measured and the height of the thickest tree in each plot.

15 trees were selected from each line. The trees were selected for a dbh which must allow the identified

cutting scheme (Figure 7) which required a top diameter of minimum 24.4 cm at the top of a 4m butt log

.

5 rows d= tree height d= 2 tree heightsFigure 2: Position of the measurement lines within the site in relation to the edge

line1: 5 planting rows back from the edge in order to avoid edge effects on

the tree growth due to the one-sided light regime at the stand edge

lines 2, 3, 4: 1, 2, 4 tree heights (20m) back from line No1; these three distances

represent the decreasing mean wind speed from the edge to the site

centre and effect a varying bending moment of the stem

The mechanical impact (shown as normalised bending moment) on the sample trees during their growth

is shown in Figure 3.

10

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 20 40 60 8

Age

norm

aliz

ed b

endi

ng m

omen

t [/]

10 m30 m50 m90 m

0

Figure 3: Variation of bending moment of the sample trees with age for the different wind exposure scenarios

3.2 Sampling strategy Altogether 60 trees, respectively 15 trees from each of the identified lines 1 to 4, were selected for the

experiments. After the characterisation of the standing trees by their outer shape and size and the

mechanical characterisation, the trees were felled. Saw logs and stem discs were sampled in a way to

allow both an analysis of the internal structure for the entire tree and an analysis of sawn timber in

construction dimensions. The sampling strategy is illustrated in Figure 4.

disc b1

disc b2disc m3

disc m4disc t5 disc t6

top log

butt log

Figure 4: Sampling pattern of saw logs and stem discs

11

12

The logs were selected to represent two positions in the tree which differed in the impact of wind

exposure. The butt log of each tree was taken at stock height and represents the wood formation at two

stages: the inner core we find the wood formation effected by higher wind exposure as the stand was

more open, the outer wood cylinder was formed under a smaller wind exposure with increasing stand

closure. The top logs represent the wood formed under the constraints of higher wind exposure as wind

speed increases with height from the ground. The logs were selected in a way that at least one, but

regularly two reference heights of other measurements (tree pulling) were included in the log length.

The top diameter of the logs also had to meet the dimension requirements of 24.4cm (butt) respectively

14.5cm (top) in order to allow the cutting scheme of the battens. The logs were about 4m long and

allowed for two thin discs to be taken at both ends of the log. The butt logs were all taken at the same

absolute height, the top logs were taken at different absolute and relative stem height due to the

restrictions of the stem dimension. A mid log was considered for the log quality assessment, but was not

further investigated with regards to end products.

In addition to the saw logs, 6 discs per tree were sampled in order to investigate the internal structure of

the stem. The discs were taken from top and bottom end of each log.

3.3 Tree characterisation

3.3.1 Spatial competition and tree morphometry

In each line 15 trees with diameters between 27 and 41 cm dbh were randomly selected which

allowed for the selected cutting scheme for the battens. Each tree has been characterised by

its spatial competition calculated from the distance to the surrounding trees and the dbh

of these trees,

the external dimension and shape of each tree stem: dbh, tree height, height-to-diameter

ratio, timber height, stem taper, stem straightness

dbh is defined as stem diameter at 1.3m stem height, measured in two perpendicular

directions,

tree height is defined as total length of the stem,

height-to-diameter ratio gives an estimate of the mechanical stability of the stem,

timber height is defined as stem height with 7cm radius over bark,

stem taper is defined as reduction of diameter in centimetre per meter stem length,

stem straightness: the butt 6 m stem length have been assessed using a scoring system

1-7 classifying the length and the number of straight logs according to the following

system (Macdonald et al 2001):

SCORE No of straight log counted in butt 6m ≥5m ≥4m<5m ≥3m < 4m ≥2<3m

1 2 1 3 2 4 1 5 1 1 6 1 7 1

the size and shape of the crown: crown length, crown projection area and crown

asymmetry, position of whorls, weight of branches:

crown length: is defined as length between lowest green whorl (2/3 to 3/4 of branches

alive) and tree top, additional record of height of lowest green branch,

crown projection: the crown extension in 4 directions (windward, leeward and

perpendicular direction in radius) and the crown projection area was estimated by the

triangle method,

crown asymmetry was described by the quotient “largest crown radius/smallest crown

radius”;

Figure 5: triangle method to estimate crown projection area

13

3.3.2 The mechanical properties of the standing stem: bending stiffness, structural Young’s modulus, swaying frequency

bending stiffness, structural Young’s modulus: a pulling rope was attached to the stem at the point

where the diameter was 14 cm and eight strain gauges were attached from 1.5m stem height up to

the rope attachment. A continuously increasing load was slowly applied to effect a slight bending

of the stem. The recorded force and strain of the peripheral fibres of the stem allow calculation of

the bending stiffness of the stem and the elastic properties of the stem material (structural Young’s

modulus). For a full description of the methodology of static bending tests on standing trees refer to

BRÜCHERT ET AL. (2000);

swaying frequency: after relaxing the tree from the static pull, the tree had been pulled strongly and

was let swaying freely until no further movements recording the variation of the strain in all 8

heights of the stem ,

Figure 6: Set up for tree pulling and tree swaying experiments

14

15

3.4 Internal stem structure The internal structure of the stem was analysed on 6 stem discs per tree if the number of discs was not

restricted by the size of the tree or the size of the disc (discs over 40 cm could not be CT scanned). The

variables were the annual radial increment of each growth ring in order to analyse the incremental

variation over time. Secondly, the density of each disc was measured on the fresh material and the air-

dried disc (to constant weight) as wood density is known as one of the main characteristics which

effects the mechanical properties of wood. The integrated density of the entire disc was preferred over

measurements on small samples as the data were used for correlation with MOEstruct which also

integrates over the cross section of the stem.

3.4.1 Density of fresh disc material:

After cutting the discs were immediately packed in plastic bags and stored in a cold-room at 4°C to

prevent any moisture loss. The fresh density [kg/m³] (mass/volume) was calculated from the mass

and the volume of each disc. The mass was measured by weighing the discs on an electronic scale

Sartorius MC1 to 0.1g. The volume was measured using the water displacement method. The

density of the fresh stem discs represents the integrated density of the fully saturated wood, but also

small proportions of the fresh density of pith and bark.

3.4.2 Density of air-dry disc material:

The discs were dried in a unheated polyester tunnel for 10 months to constant weight. The density

was measured by Computer-Tomography Scanning. The resulting Hounsfield units per pixel were

transformed into density values using the equation (Lindström, 2000):

density [kg/m³] = [Hounsfield unit + 1024]/1.024

Hounsfield units smaller than H = –921 were ignored as they represent air or other

artefacts which were not included in the calculation of the mean air-dried density of the

disc.

3.4.3 Ring width

The mean ring width was measured on all discs sampled except for the bottom disc of the butt logs.

The width of each growth ring was measured on four radii (windwards, leewards and two radii

perpendicular) using the software package WinDendro version 6.4a. The ringwidth data measured

on disc b2 (4m stem height) were used to analyse the annual increment in diameter in order to

calculate to eccentricity and stem ovality.

16

3.5 Roundwood and saw log assessment The roundwood quality was assessed by parameters which between others are used for log grading

according to the European standard ENV 1927-1 (1998). The assessment follows the log grading

standards in parts, but not full terms. The parts of the set of branch characteristics, reaction wood, resin

pockets and minor defects such as stains, insects, fungi were not assessed. The results of the log grade

assessment are, therefore, restricted in the overall evaluation of the grades.

For the log assessment, the particular parts of the entire pole have been distinguished. Two 4 m logs

(butt and top log) and one log of 1m length (mid log) have been sampled from each tree. This sampling

scheme covers stem parts of mature and juvenile wood formation, and stem parts of exposed and less

exposed phases of the tree during the wood formation.

ENV 1927 classifies four grades of log quality:

Quality class “A” First grade timber suitable for veneering and cabinet work. Normally, this

is the butt log with no knots and with few restriction to its use.

Quality class “B” Timber of good to average quality, with no requirements for clear wood

only. Knots are allowed to an extent, as is considered average for each

species.

Quality class “C” Timber of average to poor quality, allowing all quality characteristics

which do not degrade the natural characteristic of the clear wood.

Quality class “D” Timber that can be sawn into usable wood, which, because of its

characteristics, falls into none of the quality classes A, B, C.

The following characteristics have been used to qualify the roundwood and the saw logs. Table 1 gives

the limits for the evaluation of the individual characteristics for the different grades.

17

grade A B C D

Sound branches not allowed ≤ 4 cm allowed allowed

Dead branches not allowed ≤ 3 cm ≤ 6 cm allowed

Ring width ≤ 4 cm ≤ 7 cm no restriction no restriction

log diameter < 20 cm unlimited 1cm no restriction no restriction

log diameter ≤ 35 cm unlimited 1.5 cm no restriction no restriction

Log taper

log diameter ≥ 35 cm unlimited 2 cm no restriction no restriction

Table 1: Selected limits for log assessment according to ENV 1927-1 (1998)

3.5.1 Branchiness

For the log assessment, the diameter of the thickest branch [cm] in every meter of the pole length

was considered. The status of the branches were classified as follows:

Sound branches: each branch measured within the crown length has been classified as living

and sound.

Dead branches: each branch between bottom and crown height was classified as dead branches

rotten branches were not measured

3.5.2 Ring width

The ringwidth of the individual log was assessed from the measurements of ringwidth on the

sampled discs. For the final evaluation, the disc representing the larger mean ring width (lower log

grade) was used for the assessment.

3.5.3 Spiral grain

It was measured with a sharp needle at 1.5 m stem height (butt log). Spiral grain was not measured

for the middle and the top log.

18

3.5.4 Position of the pith (eccentricity, %)

It was calculated from the ring width analysis on four radii (two diameter perpendicular to each

other). For each diameter, the eccentricity of the pith was calculated and assessed separately. For

each disc, the larger eccentricity (lower quality grade) was taken into consideration. For each log,

the lower grade of both discs was used for the grading.

3.5.5 Log taper

Log taper was derived from the difference between the average diameters at the bottom and the

top end of each log (cm/m).

Not assessed: number and size of resin pockets (not relevant for Sitka spruce), reaction wood in the log

(detailed measurements on the final product), log straightness, shakes, insect attack, rot and stain.

Additionally measured:

The stem ovality was derived from the ratio between largest and smallest diameter at each end of each

log. It gives an external measure for the asymmetry of a log which needs to be considered

during sawmilling.

The size and cross-section proportion of juvenile wood in the stem was calculated from the ring width

data of each disc. The juvenility in wood formation is shown to last up to approximately

12 years of cambial age . After 12 years, fundamental wood properties such as cell wall

thickness, cell wall-to-lumen-ratio or microfibril angle change in a way during the wood

formation that physical properties (density) and mechanical characteristics of wood

improve with regards to timber utilisation. The proportion of juvenile wood in a log

defines the proportion of end products with less favoured characteristics in terms of

dimension stability and lower mechanical strength.

3.6 End-product The final product is battens of construction timber in the dimensions of 10.5 x 5.0 x 400 cm (dimension

fresh condition). The cutting scheme for the different log dimensions is shown in Figure 7. The cutting

model took into account the orientation of the prevailing wind exposure to investigate the influence of

the position of the batten in the cross section of the stem.

The statistical analysis of the effect of wind exposure on batten quality was undertaken on two sub-sets

of the original data set, comparing separately (I) battens from the butt log (battens from the inner core

versus battens from the outer stem) and (II) battens cut close to the pith (butt logs versus top logs). The

first approach allows analysis of the effect of increasing wind constraints at the same stem height as the

trees grow larger and the mechanical loading increases. The second sub-set allows comparison of wood

which has been formed at the same physiological age of the cambium but under different mechanical

constraints as windspeed generally increases with height. Comparing butt and top battens of the same

position within the stem allows quantification the wind exposure effects within the tree.

LEEWARDwind

slope

Figure 7: Cutting scheme of logs

3.6.1 Machine stress grading

The mechanical behaviour of the battens was tested under fresh conditions on a commercial stress-

grading machine Telemach Ltd. System SG-AF. The battens were bent by 3-point bending to 5.4

mm deflection and the required force was recorded in 100 mm intervals. Testing speed was 60

m/min. Each batten was tested twice, changing the direction of deflection. The average deflection

of both measurements was used to calculate the MOE automatically. The minimum MOE was

derived over the length of the batten and used for the strength classification.

19

20

The battens were graded for two different combinations of strength classes: “C24, C16,

reject” and “C16, reject” with the following limits:

C24 C16

C24/C16/reject MOE ≥ 6761 [N/mm²] MOE ≥ 5721 [N/mm²]

C16/reject MOE ≥ 3987 [N/mm²]

3.6.2 Kiln drying

The battens were dried in a conventional high temperature kiln in two loads. The drying schedule is

given in table 2. The battens were placed onto a frame and were not loaded to allow to move freely

during the drying process. Thus the battens dried without any constraints and could develop their

maximum distortion. After drying the battens were immediately placed on a trailer.

Phases Heat up Drying Drying Conditioning Cooling

Variables 1 2 3 3

T Dry Bulb (°C) 20 - 55 60 65 65 65-20

T Wet Bulb (°C) 20 - 54 55 50 64 64-20

RH (%) 97 77 46 98

EMC (%) 21 13 7 21

M/C Initial (%) approx. 120

M/C Final (%) 15 Total

Time (Hours) 12 48 60 12 12 123

Table 2: Drying schedule for kiln drying test battens

3.6.3 Dimensional stability

Distortion was measured on all battens after drying and cooling. Distortion was recorded as twist,

spring and bow (Figure 8). All measurements were undertaken over the central 2000mm of the

batten. All measurements were recorded to 0.5mm accuracy. Additionally, the moisture content

was recorded at three points (centre, +/- 1000 mm from batten centre) to correlate the distortion to

the actual moisture content of the wood and account for possible effects of the moisture variations

on the distortion.

Figure 8: Types of distortion of sawn timber

3.6.4 Modulus of Elasticity, Modulus of Rupture

MOE and MOR were measured on all battens using a universal-testing machine. The tests were

performed by shear free 4-point bending tests according to standard EN 408 (1995) with a span l

=1800 mm, distance between force application d=600 mm and gauge length l1 = 500 mm. The

battens came to failure within 3 to 7 min of the beginning of the loading.

3.6.5 Juvenile wood

Before sawing the battens, the juvenile core of 12 growth rings were marked on the cross-cut logs

at each end. The raw marked ends remained on each batten during the whole protocol of timber

grading and testing and were finally cut off as small blocks in a last stage of examination. The ratio

of juvenile wood in a batten was measured by the paper weight method. The outer shape of each

block and the corresponding contour of the juvenile wood was traced onto transparent paper and

the ratio determined by weighing both parts of each traced picture on a scale. The values for the top

and the bottom block were averaged.

21

22

3.6.6 Density

For each batten the density of the conditioned battens was measured on a central block taken out of

the batten closely to the point of failure after the tests to determine MOR. The volume of the pieces

was determined by the water displacement method, the mass of the piece by weighing.

Detailed measurements on selected trees from line 1 and line 4.

For more detailed examination of the batten quality a sub-sample of battens were selected from

material sampled in the most extreme exposure situations of the site (most exposed, line 1; most

sheltered, line 4). Out of these 30 trees 6 trees each for both lines were chosen by random for

further investigations on knottiness, compression wood presence and grain angle. The following

trees have been selected:

line trees

1 4, 5, 6, 7, 10, 11

4 3, 7, 8, 12, 13, 15

3.6.7 Knottiness

The occurrence of knots was recorded in a central length of 800mm as this length represents the

area a failure is most likely to occur when testing for MOR. The knots were measured and recorded

starting at the top end of the 800 mm length and working towards the bottom, but their actual

position along the length were not noted. Knots were measured if they were:

a single knot on the face greater than 38 mm diameter.

A single knot on the edge greater than 25 mm diameter

any knot greater than 15 mm if in a group (i.e. knots within 150mm length along the

batten), ignoring any that were 15 mm or less.

When the knot was oval, the mean diameter was used. All four surfaces of each batten were

examined.

3.6.8 Grain angle

Grain angle was measured on the tangential face of each batten. The angle is therefore viewed from

the bark towards the pith, and represents the spirality in the tree, as viewed in a similar way to the

measurements on the surface of the standing tree.

A sharp needle was used to scribe the batten surface along the fibre with several replications to

account for the variation of grain angle along the length of the batten. Each measurement consisted

of recording the distances A and B between the batten edge and the scribe over 1000 mm length.

The values were recorded either as “+”, “-“ or “0” depending upon the direction of angle.

Figure 9: Setup of grain angle measurements on battens

top

bottom

A

B

+ -

3.6.9 Compression wood

The battens were examined immediately after planing, as at that stage, before the wood surface

began to discolour, it could be seen most clearly. Areas on the surface had their boundary marked,

where, as a result of their colour and appearance, compression wood was thought to be present. All

four faces of the batten were examined over their full lengths. To record the surface of

compression wood, whose boundaries had been marked, transparent grids were placed over each

surface in turn. The grid of the faces had 50x4 rectangles each measuring 50mm long by 1/4 of the

width of the face. That for the edges had a similar number of rectangles, of 50 mm length and by

23

1/4 of the width of the edge. By viewing the batten surface through the grid, those grid rectangles

that corresponded with areas of compression wood could be noted. Cells were recorded as “blank”

for compression wood absent and “1” for compression wood present. Grid rectangles were

recorded as having compression wood present when either totally occupied, or having half or more

in both directions, along and across the batten surface.

Figure 10: Setup for measuring compression wood area

The summary values have been calculated as follows (FAIR CT 1996-1915 STUD Final Report).

For each of the 16 rows of the grid rectangles, which run along the batten length a total has been

calculated which is the sum of al the “1” values in that row. Six row totals have then been added

together to give an outer quarter total for each face or edge. It was felt that simply summing the

rows for the 4 rows was not adequate to represent the amount of compression wood present within

the cross section. When considering what compression wood has contributed to the spring or the

bow, then the difference between the levels in the outer portions on the opposite side of the cross-

section is crucial. The sum of the 4 row totals on a particular surface plus the total of the first rows

of the adjacent surfaces better represent this. However, it is acknowledged that this does not give a

full picture of the extent of the compression wood within the cross-section.

1

1 11 11 1 1 1 1

1

plastic gridcompression woodinner

outer

12

1 2 3 45678

12 11 10 9

16151413

24

25

4 Results

4.1 Selection and characterisation of the site. General stand characteristics

The selected, slightly sloping site is located at Kilmichael Forest, Argyll Forest District, (grid

reference NR 904 918, Long 5°21’40’’W, Lat 56°04’37’’N) with a NW exposed old edge. The

distance to the opposite edge in the NW direction is 55 m, this stand showing a top height of

16.7 m and closure at 11.3 m height. The area in between is covered with Sitka spruce planted in

1990 (actual height 1 to 4 m), leaving a 14.5 m wide gap with no planting (drains on both side of

the forest road and grassland). DAMS score for the site reads as 17. This reading represents severe

wind exposure. Above 17 no thinning is allowed and above DAMS 20 no planting is undertaken

due to very poor growth rate and high wind throw risk.

The even-aged stocking of the site consists of predominantly Sitka spruce with small patches of

Logepole pine (suppressed and dead) along two narrow rides perpendicular to the forest road. Trees

close to the rides were neglected for sample selection. Planting year 1953 with planting at

1.5 by 1.7 m spacing giving an initial stand density of 3900 stems/ha. There has been no thinning,

but self-thinning and distinct differentiation of the stocking have led to a wide range of diameter

distribution and to formation of tree classes from predominant to suppressed.

Table 3: An abbreviated tariff of the Kilmichael site

Sample No Mean top

height [m]

Minimum

top height

[m]

Maximum

top height

[m]

Mean

diameter

[cm]

Minimum

diameter

[cm]

Maximum

diameter

[cm]

Site 20.6 15.5 25.6 19.2 7.0 39.0

Line 1 22.0 16.2 29.5 19.9 7.0 48.0

Line 2 26.2 20.9 37.0 23.1 9.0 54.0

Line 3 27.3 21.6 31.8 23.0 11.0 52.0

Line 4 27.6 24.2 34.4 25.0 12.0 46.0

26

The top height of the site was 20.6m, which represents a medium productive Sitka spruce plantation

(general yield class GYC 10).

From line No 1 to line No 4, from the edge to the mid-forest, the top tree height of each line is

increasing from 22.0 m to 27.6m, the trees in line No1 being significantly smaller than in line No3

and No 4. The same variation holds also true for the dbh distribution in this transect. The mean dbh

increases from approximately 20 cm in line No1 to 25 cm in line No 4. The inner-forest lines differ

significantly in mean dbh from the edge line No 1.

The comparison of the height and diameter characteristics in the different lines with the tree

characteristics of the overall site show that the trees in the most wind exposed line No 1 close to the

edge copy the characteristics of the site, whereas the trees in line No 2, 3 and 4 are higher and thicker

than the site mean. These lines therefore do not represent the mean of the site in terms of height, dbh

and standing timber volume.

4.2 Characterisation of the sample trees:

4.2.1 Size and shape of the sample trees

Height, diameter at breast height, height-to-diameter ratio

Figure 11 a, b, c show the means and standard deviation of dbh, height and height-to-diameter-ratio

for the sample trees. As the trees have been sampled within a particular diameter range, there is no

difference in the mean dbhs. The dbh variation of the sample trees within line No 3 is slightly larger

than in the other sample lines. All sample trees were members of the higher tree classes “pre-

dominant”, “dominant” and “co-dominant”. The mean tree height for the sample trees increases

slightly from the edge to the stand centre from 24.9m to 27.4 m, however, no significant difference

was found between the four different lines. Height-to-diameter-ratio increases from 75.5 to 87.6,

indicating an increasing slenderness of the central grown trees under more sheltered conditions. The

height-to-diameter ratio of exposed trees close to the edge in line 1 is significant lower than for the

two central lines 3 and 4.

Figure 11: Variation of mean and standard deviation of dbh, height and height-to-diameter-ratio of the sample trees in relation to distance from the edge

0

5

10

15

20

25

30

35

0 20 40 60 80 100distance from the edge [m]

heig

ht [m

]

0.0

0.1

0.2

0.3

0.4


dbh

[m]

0

20

40

60

80

100


heig

ht-t

o-di

amet

er-r

atio

[/]

27

0

5

10

15

20

25

30

0 20 40 60 80 100


heig

ht [m

] -

mea

n ±

stan

dard

err

or

first dead whorlfirst green branchfirst green whorllargest whorl masstree height

Figure 12: Variation of tree height and the height of the crown variables in relation to distance from, the regression lines are least square fits of 2nd order polynoms

Figure 12 shows the relation of the main crown parameters: height of first dead whorl, height of the

first green branch and of the first green whorl and the height of the largest weight of a whorl. From

line 1 to line 4 (exposed to sheltered) increases the stem height of these crown parameters except for

the height of the lowest dead whorl which decreases towards the centre of the site. The statistical

analysis by ANOVA shows that the stem height for the living, green branches (lowest green branch,

lowest green whorl, height of largest whorl mass) differs significantly between line 1 and line 4. The

increase in height is probably less due to the degree of shelter than the decreasing intensity and the

decreasing amount of light in the centre of the site which leads to earlier branch death and self-

pruning of the trees.

Figure 13 shows the mean variation of the vertical and the horizontal crown projection area and the

crown asymmetry in relation to the distance from the edge. The average vertical crown area varies

between 9.4m² to 4.8m², with the significant larger crown area for the trees close to the edge

(p=0.05). The horizontal crown projection area changes in a comparable way, generally decreasing

from 33m² in line 1 to 22m² in line 4. The mean crown asymmetry varies from 2.01 to 3.23 with no

28

distinct tendency from the edge to the mid-forest due to the large variation between the trees within

the individual lines. The vertical and horizontal mean crown projection area of the sample trees in

line 1 (close to the edge) is therefore larger but more symmetric than trees in the centre of the forest.

Figure 13: Variation of crown projection area and crown asymmetry in relation to distance from the edge the regression lines are least square fits of 2nd order polynoms

0

5

10

15

20

25

30

35

40

0 20 40 60 80 100


area

[m²]

- m

ean

± st

anda

rd e

rror

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

ecce

ntri

city

[/] -

mea

n ±

stan

dard

err

or

vertical projection area horizontal projection area crown eccentricity

4.2.2 Straightness score

The straightness score is a measure on how many straight sawlogs of a particular length can be

expected from the bottom 6m of a tree. The stand scores an average of 5.8. Within the plot the

straightness score increases from 5.0 in the exposed line 1 close to the stand edge to 6.2 respective

6.1 in the sheltered centre of the stand (Figure 14) with a generally lower straightness score in line 1

than in line 3 and line 4. Thus the trees in the less exposed parts of the stand formed straighter stems.

This might be due to the fact that these trees in general have been subject to less mechanical

perturbation than the trees closer to the edge.

29

0

1

2

3

4

5

6

7

0 20 40 60 80 100distance from edge [m]

stra

ight

ness

sco

re -

mea

n +/

- sta

ndar

d er

ror

Figure 14: Variation of the straightness score in relation to distance from the stand edge (n=15)

4.2.3 Mechanical properties of the standing trees

4.2.3.1 Static pulling tests, structural Young’s modulus (MOEstruct)

4.2.3.1.1 The variation of MOEstruct with stem height

The analysis of the static bending tests shows a large variation of the MOEstruct between the trees in each

particular line and within individual trees (Figure 15). The MOEstruct varies between 2.89 and 13.48

[GN/m²] over all trees, the line average MOEstruct over all stem heights varies between 5.08 and 5.42

[GN/m²] with no significant difference between the lines. The correlation analysis for linear relations

between the stem and crown variables of the tree and the mean MOEstruct (tree) found no strong linear

correlation for any of the tested variables. The correlation coefficients are given in Appendix 1.

The statistical analysis of the source of variation for MOEstruct showed a significantly negative effect of

the stem height and a positive effect of the position of the tree on site, respectively the degree of

exposure (p=0.05). A line.height interaction was excluded from further modelling as the effect was

found to be not significant; an analysis after square root transformation of the data obtained the same

general relations.

30

The statistical model on the entity of the data set to predict MOEstruct is given in Table 4

MOEstruct = 8.208-0.1933*height+el

Line el

Line 1 0.0000 Line 2 0.2913 Line 3 0.0883 Line 4 1.1109

Table 4: Statistical model to predict MOEstruct from line and stem height

0

5

10

15

0 5 10 15 20 25stem height [m]

stru

ctur

al Y

oung

's m

odul

us [G

N/m

²]

10 m 30 m 50 m 90 m

Figure 15: Variation of the structural Young’s modulus within the tested lines. The regression lines represent least square fits of 2nd order polynomials

The analysis shows that MOEstruct decreases strongly in longitudinal direction from the bottom to the top

(Figure 15, Figure 16). A regression analysis (separately for each line) shows that a least square 2nd

order polynomial function fits the data best. Table 5 shows the equations and the R2 of the polynomial

fits. There is a trend of an increase of MOEstruct from line 1 to line 4, but due to the large variation

between the trees the MOEstruct in line 4 is not significantly higher than in line 1, 2, and 3.

31

line Equation R²

line 1 (10 m) MOEstruct = 7.537 - 0.0785x - 0.0033x² 0.1507

line 2 (30 m): MOEstruct = 7.929 - 0.0413x - 0.0074x² 0.4062



Table 5: Regression models of the relation between absolute stem height x and MOEstruct

0

2

4

6

8

10

0 5 10 15 20stem height [m]

stru

ctur

al Y

oung

's m

odul

us

[GPa

]

tree 4_2 tree 2_12tree 2_4 tree 1_5

Figure 16: Inter-tree variation of structural Young’s modulus for individual sampling trees (signature refers to: line_tree ID)

4.2.3.1.2 Heterogeneity of MOEstruct

Further analysis shows the degree of intra-tree variation of MOEstruct within the individual tree (Figure

17). The difference in MOEstruct between two adjacent points varies up to 3.2 GN/m² per meter distance.

The heterogeneity of MOEstruct (var) was classified in three groups:

I. var > 1.0 GPa/m,

II. 0.5 GPa/m < var ≤ 1.0 GPa/m

III. var < 0.5 GPa/m

32

0

2

4

6

8

10

12

0 5 10 15 20stem height [m]

stru

ctur

al Y

oung

's m

odul

us

[GPa

]

tree 1_4 tree 3_13

Figure 17: Variation of structural Young’s modulus within the stem for individual sampling trees (signature refers to: line_tree number)

Figure 18 shows the distribution of the heterogeneity in these three classes. The proportion of very small

changes of MOEstruct in axial direction increases slightly from 60% to 70% from exposed line 1 to

sheltered line 3 and 4. At the same time there is a decrease in the proportion of large “jumps“ of

MOEstruct over 1 GN/m² per m length in line 1 (16%) to between 5-7% in line 2, 3 and 4. χ² tests for

differences in the frequency show that within each line the frequency of negligible and small local

changes in MOEstruct are similar whereas the frequency of large local changes is significantly lower in

these three lines. The inter-line comparison shows that in line 1 the frequency of large local changes in

MOEstruct is significantly higher than in line 2, 3 and 4 (Appendix 2).

However, the analysis of the stem shape and branch characteristics showed that these irregularities in

MOEstruct were not related to structural heterogeneity such as branches or whorls, as no relation could be

found between the change in MOEstruct and the positions where the strain gauges had been placed (at a

whorl, close to a whorl or between two whorls). Thus within the site, the exposed line 1 shows

onaverage the lowest MOEstruct and the largest degree of heterogeneity in MOEstruct.

33

0

20

40

60

80

100

10 30 50 90distance from edge [m]

perc

enta

ge o

f MO

E str

uct v

aria

tion

[%]

var >1.0 GPa/m0.5 GPa/m< var < 1.0 GPa/mvar <0.5 GPa/m

Figure 18: Distribution of the intra-tree heterogeneity of MOEstruct in relation to the degree of exposure

4.2.3.2 Dynamic pulling tests, swaying frequency

Figure 19 shows a typical pattern in variation of the strain on the stem surface during several swaying

cycles. Due to damping initiated by crown clashing and internal energy loss in the stem the swaying

amplitude reduces in a regular pattern.

34

-400

-300

-200

-100

0

100

200

300

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101

106

111

116

121

126

131

136

141

146

151

156

161

stra

in [d

igits

]

1.0m3.1m5.1m7.2m10.2m13.2m15.2m17.3m

Figure 19: Variation of strain at different stem heights due to tree swaying for an individual tree over time (sec)

0

0.1

0.2

0.3


sway

ing

freq

uenc

y [H

z] -

mea

ns ±

sta

ndar

d er

ror

0

10

20

30

tree

hei

ght [

m]

swaying frequencytree height

Figure 20: Variation of the swaying frequency and tree height in relation to the distance from the edge an increasing shelter

Figure 20 shows the variation of the natural swaying frequency within the stand. The frequency varies

for all tree between 0.13Hz and 0.41Hz. The mean swaying frequency decreases from 0.27 Hz in line 1

to 0.22 Hz for line 4. The ANOVA shows that in general there are no statistical significant difference in

35

the swaying behaviour of the trees between the four lines due to the large variation within each line

(p=0.05). The largest variation in swaying frequency within a line is found in line 1 close to the edge.

The statistical analysis shows that the variation in swaying frequency is not directly related to the degree

of exposure represented by line 1 to line 4, but is closely related to the height and the dbh of the tree

which vary between the lines. Swaying frequency decreases with increasing tree height and increases

with increasing dbh. Both variables have a strongly significant linear relation to the frequency

(p<0.001). We also tested for the effects of stem shape, crown parameters (crown length, crown

eccentricity, sailing area, crown radii), of the MOEstruct and the effect of the competition index

(Appendix 3). There were no other significant sources of the variation of the swaying frequency than

tree height and dbh. As we selected the trees to have a small variation of diameter (Figure 11b) the

reduction of the swaying frequency from line 1 to line 4 is mainly due to the increase in tree height

(Figure 11a). A linear model fitted the data best and accounts for 49.8% of the variation.

f=0.3960-0.01429*h+0.685*dbh

Figure 21 shows the relation between stem form and swaying frequency. There is a wide variation for

the tested trees. The strong linear relation as given in Gardiner (1989) could not be found for the tested

trees.

y = 929.35xR2 = 0.3868

0.0

0.1

0.2

0.3

0.4

0 0.0001 0.0002 0.0003 0.0004 0.0005

radius at stem base/ tree height2

sway

ing

freq

uenc

y [H

z]

10 m30 m50 m90 m

Figure 21: Natural swaying frequency of the sample trees. The regression line for all data represents a least square fit and is forced through the origin.

36

4.2.4 Internal stem structure

4.2.4.1 Density of the fresh discs

Figure 22 shows the variation and the linear regression fits of the density of the fully saturated stem

discs. The fresh density of the individual discs varies in all lines in a wide range from 492 [kg/m³] to

1062 [kg/m³]. Due to the large differences between the individual trees, there is no statistical significant

difference in the means of the fresh density of trees of all four lines (p=0.05).

The analysis by Wald test identified the tree height as the main source of variation of fresh disc density

(Appendix 4). The position of the tree within the site (line-effect) was not identified as a statistical

significant source of variation, neither did we find a line.height interaction effect. Further analysis

showed that the percentage of explained variation does not increase when considering height2 and

height3 and thus these terms were not included in the model. The linear model is given below.

δfresh = 718.0 + 5.807*height [kg/m3]

0

200

400

600

800

1000

1200

0 5 10 15 20 25

stem height [m]

fres

h di

sc d

ensi

ty [k

g/m

³]

10 m 30 m 50 m 90 m

Figure 22: Variation of the fresh density within the tested lines. The regression lines represent least square fits of linear relations.

37

38

In all lines the fresh disc density increases with increasing stem height. In the most extreme lines line 1

and line 4 the slope of increase appears to be similar (Table 6), but the basic fresh density seems lower

in line 4. The intermediate lines line 2 and line 3 show a smaller increase of fresh density with stem

height. The basic density is slightly higher in line 2 and lower in line 3 than in line 1.

line Equation R² line 1 (10 m) δfresh = 732.59 +7.12x 0.1346 line 2 (30 m): δfresh = 753.16 + 2.20x 0.0212 line 3 (50 m): δfresh = 703.32 + 4.80x 0.1101 line 4 (90 m): δfresh = 691.83 + 7.17x 0.1654

Table 6: Regression models of the relation between absolute stem height and fresh disc density of the individual lines

4.2.4.2 Density of air dry discs

The density of the air-dried discs also shows a large variation between 323 [kg/m³] and 603 [kg/m³].

The Wald analysis found a significant effect of the tree height and of the degree of exposure (line effect)

as source of the variation (p=0.05) (Appendix 5). The analysis also showed a height.line interaction as

additional source of variation which was also included in the statistical model to predict air-dry disc

density as given in Table 7.

δair-dry = 419.4 + (2.87+ e1)*height + e2

Line e1 e2

Line 1 0.000 0.00 Line 2 -3.117 -3.80 Line 3 -1.407 -29.60 Line 4 -0.098 -34.59

Table 7: Statistical model to predict air-dry disc density from line and stem height

As for the fresh disc density we found an increasing air-dry disc density with increasing stem height.

Line 1 closest to the stand edge shows the highest average disc density both in fresh and air-dry

condition. In line 4 we found on average the lowest disc density at the stem base and the steepest

increase in density to the top. For line 2 and 3 we found an intermediate density at the base and the

lowest density towards the top of the stem.

0

100

200

300

400

500

600

700

0 5 10 15 20 25

stem height [m]

air-

dry

disc

den

sity

[kg/

m³]

10 m 30 m 50 m 90 m

Figure 23: Variation of the air-dry disc density within the tested lines. The regression lines represent least square fits of linear relations.

line Equation R² line 1 (10 m) δair-dry = 429.96 +1.7058x 0.0319 line 2 (30 m): δair-dry = 419.66 - 0.5278x 0.0037 line 3 (50 m): δair-dry = 395.35 +0.9944x 0.0153 line 4 (90 m): δair-dry = 381.94 +3.0089x 0.1238

Table 8: Regression models of the relation between absolute stem height and air-dry disc density

4.2.4.3 Radial increment

In order to analyse the effect of exposure on the growth pattern of a tree we focused on the two radii

representing the windwards and the leewards side of the stem. The disc at 4m stem height was

considered the most appropriate disc as it represents a stem age with a large number of growth rings, a

long time period of wind exposure, and a ring structure not influenced by buttresses or the root stock

which could cover the exposure effect in the growth pattern. The radial growth was analysed in 5 years

intervals taking the ring ages of 5 years, 10 years, 15 years, 20 years and 25 years.

39

0

0.02

0.04

0.06

0.08

0 10 20 30

ring age at 4m stem height [years]

∆ra

dius

l-w n

orm

aliz

ed b

y m

ean

diam

eter

tot

10 m30 m50 m90 m

Figure 24: Difference in radial increment in windward and leeward direction – the symbols represent the mean of a line, the error barrs represent the standard error of the mean

Figure 24 shows the normalised difference between both radii. The difference in leewards and

windwards radius increases with age for all lines which corresponds with an increasing eccentricity of

the stem. In line 1 we found the largest difference between the radius in leewards and windwards

direction, in line 4 the smallest, line 2 und 3 were intermediate. For the youngest age there appears no

difference in growth between all four lines. When the trees getting older, the edge trees in line 1 grow

more eccentric than the trees in lines 2, 3 and 4. Correspondingly the most sheltered trees in line 4 show

the smallest stem eccentricity. At an age of 25 years, the difference in eccentricity between line 1 and

line 4 is found to be statistical significant different (p=0.05) (Appendix 6). From this it follows that the

more exposed trees are when growing the more they lay down wood on one side, the leewards side of

the stem and the more they develop reaction (compression) wood in comparison to more sheltered trees

which grow in a more homogenous manner.

40

4.3 Roundwood and saw log assessment

4.3.1 Branchiness

Branchiness is one of the most important criteria for log quality. The occurence of branches on a log

represents a combination of unwelcome log and wood properties which will be carried along the chain

to the final product. Branchiness represents a local heterogeneity of the fibre structure, leading to a

weakening of the mechanical strength of the wood and different drying characteristics. The standard

ENV 1927 classifies saw logs based on the status of a branch (ingrown or sound, dead, unsound) and

the branch diameter.

0

10

20

30

40

50

60

70

butt mid top

position of log in the stem

diam

eter

of t

he th

icke

st b

ranc

h pe

r log

[mm

] - m

ean

+/- s

tand

ard

erro

r

10 m30 m50 m90 m

Figure 25: Variation of the diameter of the thickest branch per log

The individual diameters of the thickest branch per log varied in a wide range between 15 mm and

104 mm (Appendix 7). The average branch density of the thickest branch per log (butt, mid, top) and

line 1, 2, 3, 4 varied between 25 mm and 55 mm with the largest variance for the top logs in line 1 (10m

from the edge) (Figure 25). The lowest minimum values occurred on the logs from the butt position of

the stem. The largest branch diameters were measured on the top logs. The statistical analysis showed

two trends of variation for the branch diameter. Independently for all lines, there is an increase in branch

diameter from the bottom of the tree to the top which follows the general development of the canopy.

41

The variance analysis showed that the increase in branch diameter between the bottom and the top log is

significant in all lines except line 2 and is even significant between mid log and top log in line 4

(p=0.05).

The increase of branch diameter with height varies with distance from the edge. In each group of log

position (butt, mid, top), the branch diameter decreases from line 1 to line 4, but the differences in

diameter are not statistically significant (p=0.05). The analysis also showed no significant line.log

interactions. However, the overall decrease of branch diameter from the edge to the centre of the site is

less the effect of changing shelter than the effect of canopy shading and lower light availability in the

centre of the site which leads to more effective self-pruning.

0

10

20

30

40

50

60

70

80

90

100

10 30 50 90 all


perc

enta

ge o

f log

s pe

r gra

de [%

] -

bran

chin

ess

grade Dgrade Cgrade Bgrade A

Figure 26: Percentage logs per grade - branchiness

The classification of the logs according to ENV 1927 – 1 (1998) is shown in Figure 26. Due to the

fact that all trees showed dead branches to the bottom of the stem no log was graded as grade A,

which requires a defect-free surface without branches. In total, 30% of the logs were classified as

grade B, 55% as grade C and 15% as grade D. The comparison between the individual lines shows

a similar distribution. In all lines, logs of grade C have the largest proportion of between 44% to

42

43

68%. A lower percentage of logs of between 23% to 36 % were classified as a higher quality grade

B and between 7% and 23% were graded in the lowest quality grade D. Chi-square tests showed

that within each line the frequencies of grades B, C and D are significantly different. The

comparison between the lines shows that for each grade B, C, D the frequency of the individual

grades is very similar and does not differ on a significant level (p=0.05).

The frequencies of the grades separated by log positions (butt, mid, top) reflect strongly the

variation of branch diameter from bottom to top. Whereas 60% of the butt logs were graded as

grade B and 3% as grade D, the distribution changed drastically for the top logs with 6% of the top

logs classified as B, but 30% graded as D.

4.3.2 Ring width

Ring width is closely related to the wood density and gives a first indication of the density variation of a

log. Average ring width is very important for log quality because it gives a first indication on the

average wood density and the density contrast in the cross section. For the individual logs the average

ring width varied between 2.8 mm and 7.5 mm.

Figure 27 shows the variation of mean average ring width for the measured logs. The mean ring width

of log position by line varied between 4.0 mm and 5.5 mm, for position butt log and mid log the mean

ring width decreases by about 9% (0.4 mm) from line 1 (close to edge) and line 4 (centre of site). The

top logs do not show such trend. However, the statistical analysis showed that there is no statistical

significant difference between the lines. The variation of mean ring width can only be explained by the

log position, not by line effects or line.log interactions. The comparison between butt log and top log

shows a increase of average ring width from bottom to top. The reason is the presence of a high

proportion of pith-related juvenile wood which is characterised by a generally larger ring width in order

to support quick and efficient water transport in young shoots.

0

1

2

3

4

5

6

butt mid top


ring

wid

thm

ean [

mm

] - m

ean

+/- s

tand

ard

erro

r

10 m30 m50 m90 m

Figure 27: Variation of mean ring width

0

10

20

30

40

50

60

70

80

90

100

10 30 50 90 all


perc

enta

ge o

f log

s pe

r gra

de [%

] - ri

ngw

idth grade C

grade Bgrade A

Figure 28: percentage of logs per grade – ring width

These results suggest a relatively uniform growth ring structure of the logs which should be reflected in

a relatively homogeneous log quality. Figure 28 shows the distribution of logs into the quality grades.

44

45

The average ring width of the logs between 4 mm and 5.5 mm results in a very high percentage of logs

classified as grade B (between 67 % and 86%, average 78%). Additionally, the lower percentage in

grade B corresponded with a higher proportion of logs in grade A adding up to 98% of all logs graded

into the best two quality grades. Grade C was only present in line 1 and line 3 and did not exceed 7%.

The discrepancy between the results on eccentricity of the radial increment parallel to the wind direction

(4.2.4 Internal stem structure) and the homogeneous results on ring width with regards to log grading

indicates a problem of the grading standard ENV 1927. As the standard asks for representative radii on

a cross cut, the measurement integrates over the whole area and discriminates local heterogeneity which

could be important in further timber processing.

4.3.3 Spiral grain

Spiral grain describes the degree of angular orientation of the wood fibres of the stem. The spiral grain

is reflected on battens by the grain angle which is known to influence the level of distortion following

drying. The data presented were only obtained from the butt logs.

For the tested trees the orientation of the fibres varied between of 0 [cm/m] and 21 [cm/m]. Figure 29

presents the variation of the means of spiral grain per line. The means of each line range between 3

[cm/m] and 5 [cm/m] with a large variation for each line. The ANOVA analysis showed that there is

difference between the lines and the degree of shelter, respectively.

The quality classification of the logs with respect to the spiral grain reflects the heterogeneous picture of

the stand (Figure 30). All possible grades A to C are present with a varying proportion for the different

lines. The low mean spiral grain in line 4 is directly reflected by the high percentage of 53% “A“ grade

logs. Correspondingly, the high mean spiral grain in line 2 resulted in a low percentage of high quality

logs. Line 3 also shows a high percentage of grade “A“ log (47 %), but with a high mean of grain angle.

The large variance in line 3, however, indicates a large proportion of logs characterised by big fibre

angles. These logs, subsequently were graded into grade C, the lowest possible quality grade resulting

from spiral grain. Nonetheless, despite the detailed picture of grade distribution for the logs, chi-square

tests showed no differences for the frequencies of the individual groups.

0

1

2

3

4

5

6

7

10 30 50 90


spira

l gra

in [c

m/m

] - m

ean

+/- s

tand

ard

erro

r

buttFigure 29: Variation of the spiral grain angle

0

10

20

30

40

50

60

70

80

90

100

10 30 50 90 all


perc

enta

ge o

f log

s pe

r gra

de [%

] -

spira

l gra

in

grade Cgrade Bgrade A

Figure 30: Percentage of logs per grade – according to spiral grain (butt logs only)

46

4.3.4 Position of the pith (log eccentricity)

The pith position and the subsequent degree of eccentricity of a log strongly influence the procedures of

timber processing which thus affect the quantitative out-turn and the yield. Figure 31 shows the

eccentricity of the tested logs normalised by the stem diameter, grouped by log position and degree of

exposure. Individual log eccentricitynorm varied in a wide range between 0.02 and 0.70, the means vary

in the range between 0.22 and 0.30 with a large variation in each group. In the bottom log the

eccentricity decreases from the most exposed line 1 to most sheltered line 4. For the top logs the

opposite trend holds true, the eccentricity increases from stand edge to the centre of the site. The mid

logs in all lines showed a similar eccentricity except line 3 which is even more eccentric than the top

logs in line 4. However, the statistical analysis shows that there is no statistical difference between the

single groups due to their large variance.

The analysis of the variance show that neither line (exposure) nor the log position (butt, mid, top)

explained much of the variation in eccentricity of the logs.

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

butt mid top


ecce

ntric

ityno

rmal

ised

- m

ean

+/- s

tand

ard

erro

r

10 m30 m50 m90 m

Figure 31: Variation of log eccentricity

47

Due to the large variation of log eccentricity the classification of the logs resulted in 35% logs in grade

“A”, the frequencies of 39% in grade “B” and 26% in grade “C” with no difference in the frequencies

on a statistical significant level (p=0.05). The detailed analysis of the distribution of the logs into the

three quality grades show that this holds true for all lines. It appears that there is a slightly lower

percentage of logs grade “C” (20 to 30%) than grade “A“ and “B“. However, this means that one third

of the logs are graded into the lowest possible quality class which allows only a restricted utilisation of

the timber.

0

10

20

30

40

50

60

70

80

90

100

10 30 50 90 all


perc

enta

ge o

f log

s pe

r gra

de [%

] -ec

cent

ricity


Figure 32: Percentage of logs per grade due to eccentricity only

4.3.5 Log taper

The log taper (the reduction in diameter per tree length) varied in a wide range between 0.21 cm/m and

3.87 cm/m.

Figure 33 shows the variation of the means with respect to the log positions and the four levels of

exposure. Both “line” and “log position” account for about 31% of the variation of the log taper, there is

no significant line.log interaction (p=0.05, Appendix 11). The trend of variation is the same for all four

lines, a high taper for the butt logs, a decline in taper for the mid logs and again an increase in taper for

the top logs. The results of the post-hoc-tests for differences between the means is given in Appendix

48

11. Due to the large variation within each group there is no statistical significant difference in the means

between the four lines when comparing the logs of the three different stem positions.

0.0

0.5

1.0

1.5

2.0

butt mid top

position of batten in the stem

log

tape

r [cm

/m] -

mea

n +/

- sta

ndar

d er

ror

10 m30 m50 m90 m

Figure 33: Variation of the log taper

For butt logs (Figure 33: Variation of the log taper) the log taper only used diameter measurements from

1.3m upwards in order to eliminate the effect of stem swelling by buttresses for the log grading.

However, comparing these taper data with the “actual” tapering from the bottom end of the log to its top

end, one finds a larger effect of buttresses in line 1 and line 2, which are both more exposed to wind

constraints. The mean stem taper increases by 0.5 to 0.6 cm/m when considering the bottom 1m stem

length in these two lines, while the taper increases only by 0.2cm/m in line 3 and line 4. Thus the mean

of taper exceeds the limits the limits for grade “B” in line 1 and line 2 for trees with a dbh larger than 35

cm, which results in a classification in the lowest quality grade.

49

The grading of logs considering the taper separately does not allow any grade “A” by its own. Taper

only is considered to grading in combination with other grading parameters (ENV 1927-1, 1998). The

log grading considering the log taper individually resulted in a distribution of grade “B” and “C” as

shown in Figure 34. The majority of the log (83% overall) were classified as higher grade “B” leaving

only 17% in the lower log grade. The frequency analysis by Chi-square tests showed that this

distribution is not different between all four lines (p=0.05). The comparison broken down by log

position, however, showed the butt logs showed the highest percentage of grade “C” logs with 35%

(mid: 2%, top: 15%).

0

10

20

30

40

50

60

70

80

90

100

10 30 50 90 all


perc

enta

ge o

f log

s pe

r gra

de [%

] -

log

tape

r


Figure 34: Percentage of logs per grade – log taper

4.3.6 Log ovality

The log ovality describes the ration between the largest and the smallest diameter on a log. It therfore

combines information of log diameter and log eccentricity as the first criterion does not give a picture of

the log shape and the later only describes that individual diameter which is characterised by the largest

radial contrast. However, log ovality is not included in the standards as a parameter to classify logs.

50

Log ovality varies for individual logs between 0% and 16%. Figure 35 shows the variation of the means

ovality for the different log positions at the four distances from the edge. The mean ovality changes

between 4% and 7%. The statistical analysis and the ANOVA showed that the variation of the log

ovality is not significantly different between either the three log positions in the individual line or for

the same log position (butt, mid, top) in the different lines and levels of wind exposure. There appears

to be a trend of decrease in log ovality for butt and top logs, but not for the mid log where line 3 showed

the highest log ovality. This differing and higher log ovality corresponds with the significantly higher

eccentricity of these logs (Figure 31).

0.0

0.2

0.4

0.6

0.8

1.0

1.2

butt mid top


log

oval

ity [/

] - m

ean

+/- s

tand

ard

erro

r

10 m30 m30 m90 m

Figure 35: Variation of log ovality

51

4.3.7 Proportion of juvenile wood

Pith related juvenile wood is mainly characterised by thin cell walls and large cells resulting in a low

wood density and a large microfibril angle. Both characteristics are closely related to a reduced

mechanical strength of the wood and a large tendency to distortion of the timber. The proportion of

juvenile wood in a log thus directly determines the proportion of sawn products affected by less

favourable wood properties. The juvenile core was defined to include the first 12 years of growth. Thus

the dimension of the juvenile core for the different log positions gives an indication on the early wood

formation of the stem at this particular stage of stem development.

0

10

20

30

40

50

60

70

80

butt mid top


juve

nile

cor

e [%

of l

og v

olum

e] -

mea

n +/

- sta

ndar

d er

ror

10 m30 m50 m90 m

Figure 36: Variation of the proportion of juvenile wood

Figure 36 presents the mean proportion of juvenile wood volume per log for butt, mid and top logs. The

means per log position increase significantly from the butt log position to the top log position which is

due to the decreasing diameter of the tree with increasing height. The log position accounts for 82% of

the observed variation of juvenile wood share in logs, the level of wind exposure (line effect) and

line.log interactions were not found to be significant in helping to explain the variation. These results

indicate that the formation of the stem in the first twelve years was not effected by varying mechanical

52

constraints and lead to a relatively similar wood formation which might be reflected by the properties of

the battens produced from these inner stem parts.

4.3.8 Log classification according to ENV 1927-1 “Qualitative classification of softwood round wood – Part 1: Spruces and firs”

The log classification by ENV 1927-1 classifies a log by a range of different characteristics and

properties which have to meet particular limits. The parameter which presents the lowest quality of the

log determines the overall classification of the log. Only an extremely favourable performance in one

characteristic can compensate for a small deviation from the required limit in another characteristic. The

test material has been classified by the characteristics presented above.

0

10

20

30

40

50

60

70

80

90

100

10 30 50 90 all


perc

enta

ge o

f log

s pe

r gra

de [%

]

grade Dgrade Cgrade Bgrade A

Figure 37: Results log grading – classification after ENV 1927-1

The results of the log classification are shown in Figure 37. The tested logs were graded into the grades

“B”, “C” and “D”. The highest grade “A” which occurred for individual characteristics were

“downgraded” by a less good performance according to other properties. The largest proportion of logs

(70%) was classified as “C, timber of average to poor quality with characteristics which do not degrade

the natural characteristics of the clear wood”, 15% of the log were classified as grade “B” and 15% as

grade “D”. The frequencies for grade “B”, “C” and “D” varied slightly between the different lines of

53

wind exposure, but not at a statistical significant level (p=0.05, Appendix 14). Thus in general the trees

grown under the largest wind exposure did not perform differently in terms of log quality from the most

sheltered trees on the site.

Figure 38 presents the analysis on which criterion determined the final log grade. Between 50% and

68% (61% overall) of the logs were downgraded by a poor performance in branchiness, only 2% to 15%

(10% overall) were downgraded due to a large stem taper. The combination of branchiness and taper

accounts for another 4% to 25% (9% overall) of logs downgraded. It is obvious that the performance in

branchiness appears more important for the grading results and the log quality than the stem form and

shape. However, branchiness is strongly affected by the planting density and the stocking of the site and

less strongly by wind exposure.

0

10

20

30

40

50

60

70

80

90

100

10 30 50 90 all


perc

enta

ge o

f log

s do

wng

rade

d [%

]

all grades equal

spiral grain, eccentricity,ringwidthbranchiness & taper

taper

branchiness

Figure 38: Percentage of logs graded by the individual criteria • “branchiness“ summarise the singular effect of branchiness and combinations of

branchiness and other criteria except “taper“, • “taper“ summarise the singular effect of taper and combinations of taper with other

criteria except “branchiness, • “spiral grain, eccentricity, ringwidth“ represent occurrence of the singular effects of

each criteria.

54

4.4 End product, quality of battens

4.4.1 Stress grading

The overall comparison of the batten performance in stress grading showed three significant

components for the observed variation in (minimum) MOEmin: wind orientation (leewards/ windwards),

log position (butt, top) and exposure (line 1 to 4) (p=0.05). There was no interactions found between the

main factors “orientation”, “position” and “line”. The comparison of the entity of the data set which did

not separate between the different lines showed that in general the top log battens had only a slightly

lower mean MOEmin than the butt log battens. Battens cut from the windward side of the stem/log had a

higher mean MOEmin compared with battens from the leeward side of the log. However, there occurred a

difference in MOEmin between the centrally positioned and the more peripherally positioned butt battens.

Within the site, the MOEmin increased generally with increasing distance from the edge and increasing

wind shelter.

0

2

4

6

8


MO

E min

[GPa

]

butt battens leewardsbutt battens windwardstop battens leewardstop battens windwards

00

Figure 39: Variation of MOEmin of central positioned battens from the butt and the top log (symbols represent the mean of each line, the error bars the standard error)

Figure 39 shows a comparison of the central positioned battens from the top and the butt log close to the

pith. There was a general increase in MOEmin for the central butt battens from the exposed edge to the

sheltered centre of the stand from 5.4 GPa (mean of leeward and windward battens) to 6.2 GPa. At the

same time, the MOEmin in the top battens declined from 6.73 GPa to 6.00 GPa from line 1 to line 4. The

orientation with respect to the wind did not alter the MOEmin of these battens from either the butt or the

top logs within each line.

55

0%

20%

40%

60%

80%

100%

10 30 50 90distance from edge [m]

perc

enta

ge o

f bat

tens

C 24 C 16 reject

Figure 40: Distribution of battens qualifying for C24, C16, reject

Figure 40 shows the distribution of the battens for grading C24/C16/reject which stands for a higher

quality grading. About 30% of the battens were rejected overall, about 38% were graded as C24 suitable

for higher quality requirements (Appendix 15). The distribution of quality grades switched between

battens from line 1 (most exposed) to lines 2, 3 and 4 (more sheltered). In line 1 almost 45% of the

battens were rejected due to low MOEmin. and only 55% of the battens were classified as suitable for

higher quality purposes. For line 2, 3 and 4, the out-turn of suitable battens was higher at 74% to 77%.

However, grading according to classification “C16/reject”, which classifies for a lower strength,

identified only 2% of rejected battens in each line. The detailed analysis shows that about 42% of the

battens from line 1 had been down graded from “C16” in “C16/reject” to “reject” in “C24/C16/reject”

whereas 28% had been upgraded from C16 to C24 (Figure 41). For line 2, 3 and 4, the trend was the

other way around, more battens were upgraded than down graded. However, the overall out-turn from

the site is higher for the lower strength classification which will be preferred as the financial outcome is

also higher overall than for the higher classification but lower number of battens (BRE, oral

communication).

56

0

10

20

30

40

50


perc

enta

ge o

f bat

tens

gra

ded

diffe

rent

ly

down graded (C 16 to reject)upgraded (C 16 to C 24 )

Figure 41: Change in strength classification between grading specifications “C24/C16/reject” and “C16/reject”

4.4.2 Modulus of elasticity, modulus of rupture

MOE and MOR are the main properties to describe mechanical suitability for construction purposes of

timber. The MOE represents the stiffness of the material, the MOR its strength.

The mean MOEstat of the battens varied strongly between 6400 N/mm² and 9600 N/mm² in the different

positions of the tree (Figure 42). The analysis of the variance showed that “wind orientation” of batten

and “ position of batten in the cross section” were significant effects to explain the variation of MOEstat

(p=0.05), interaction effects between line, log position and line.log.batten position also did add up to

explain some of the variance. However, only about 20% of the variance were explained by the analysed

factors. Due to the large variations there was no significant differences between the individual positions

of battens in the logs with respect to the entire data set (p=0.05) (Appendix 16).

57

0

2000

4000

6000

8000

10000

12000

14000

butt c

entra

l

butt i

nner

leeward

s

butt o

uter le

eward

s

butt i

nner

windward

s

butt o

uter w

indward

s

top in

ner le

eward

s

top o

uter le

eward

s

top i

nner

windward

s


MO

E sta

t [N

/mm

2 ] - m

ean

+/- s

tand

ard

erro

r

10 m30 m50 m90 m

Figure 42: Variation of mean MOEstat

The detailed analysis of MOEstat on sub-data set (1) (butt versus top, inner position) showed the highest

values of MOEstat for battens from the top logs from line 1 (Figure 43a). Comparing the different lines,

the MOE of the battens of the same position decreased from line 1 to line 2, 3, and 4, while the MOE of

the inner battens increased from the edge to the centre of the site. Similarly to the analysis of the whole

data set, the variation within each group did not allow testing for significant differences between the

groups. Only in line 1 were the battens from the top logs significantly stiffer than the battens cut from

the bottom log. The comparison of battens converted from the butt logs showed a similar pattern of

variation independently from the line (Figure 43b). There was an increase in MOEstat from line 1 to line

2 and line 3, but a slight decrease towards the most sheltered line 4. However, this was not significantly

different in mean MOEstat. The increase in MOE was most distinct for battens “outer leewards” between

line 1 and line 2. These battens were cut from a position in the cross section where the wood was

influenced by compression wood on one hand but was also characterised by a homogenous wood

structure due to decreasing ring width with age (Figure 27). In line 2 the exposure to wind was already

reduced to a degree that a stiffer wood structure was developed locally. The trees did not react to

perturbation by the wind as much as the trees did in line 1. With increasing age this difference in wood

58

formation became most obvious at the stem position where generally the highest bending stresses

appeared.

0

2000

4000

6000

8000

10000


MO

E sta

t [N

/mm

2 ]

butt inner leewardsbutt inner windwardstop leewardstop windwards

00 0 20 40 60 80 10distance from edge [m]

butt outer leewardsbutt inner leewardsbutt inner windwardsbutt outer windwards

0

Figure 43: Variation of MOEstat for battens from the different positions (a – inner positions butt compared to top positions; b- butt positions close to pith and periphery)

Figure 44 presents the variation of MOR with batten position. The MOR of individual battens varied

between 25 N/mm² and 42 N/mm². The analysis of variance showed that the orientation with respect to

the prevailing wind direction and the position of the battens within the stem had a significant effect on

the variation of MOR, with no interactions between those factors (p=0.05) (Appendix 16). Due to the

large variation within each group, the ANOVA analysis on the entire data-set showed no significant

difference either between the lines nor between battens from butt log or top logs nor between battens

from the windwards or leewards half of the log.

The analysis on the sub-sets of the data showed the variation of the MOR in more detail (Figure 45).

The wood close to the pith characterised appeared very heterogenous in MOR. The different batten

positions showed no obvious trend. The MOR of “butt inner windwards” positioned battens increased

slightly from “exposed” (line 1) to “sheltered” (line4) as did the MOEstat. The MOR of the most exposed

positioned “top battens” decreased from line 1 to line 4, however. The comparison to the butt positions

showed the differentiation in MOR. The “outer butt position, windwards”, characterised by the most

homogenous and densest wood showed the highest MOR in all four lines. The outer leewards batten

position followed in strength, probably due to its increased density, and both inner positions, leewards

and windwards, turned out to be the weakest.

59

0

5

10

15

20

25

30

35

40

45

50

butt c

entra

l

butt i

nner

leeward

s

butt o

uter le

eward

s

butt i

nner

windward

s

butt o

uter w

indward

s

top in

ner le

eward

s

top o

uter le

eward

s

top i

nner

windward

s

top o

uter w

indward

s

MO

R [N

/mm

2 ] - m

ean

+/- s

tand

ard

erro

r

10 m30 m50 m90 m

Figure 44: Variation of MOR

0

10

20

30

40


MO

R [N

/mm

2 ]

butt inner leewardsbutt inner windwardstop leewardstop windwards

00

0

10

20

30

40


butt outer leewardsbutt inner leewardsbutt inner windwardsbutt outer windwards

00

Figure 45: Variation of MOR (different positions within the stem) with distance from stand edge

60

61

However, the results suggest that for the entity of the battens the wind exposure did not modify the

mechanical properties in such a way that a separation of battens appears reasonable for practical use.

This is supported by the results of the stress grading tests.

4.4.3 Distortion (twist, spring, bow)

The distortion of the sawn and dried product is the second main group of characteristics to determine

timber quality. Non-straight battens cannot be used for high quality construction purposes and need

additional treatment such as planing in order to re-shape the piece. This reduces the yield and the

financial out-turn from production. Distortion comprises four different types of warp: twist, spring, bow

and cupping. The later will not be presented in this report as it is more important to boards than to cants

and battens.

4.4.3.1 Twist

The twist of the battens varied individually between 0 mm and 55 mm for all the battens. The variation

of the means is presented in Figure 46. The average twist values ranged between 2.6mm and 33.9mm

with a large variation within each group. The analysis of variance showed that the “line”, “log position”

and “position in the cross section” accounted for 46% of the observed variance (p=0.05) (Appendix 17).

There was no interaction effect between the main factors.

For the entity of the data set, the test for differences in the means did not show a statistical significant

difference between the lines. Thus there is no evidence for the effect of wind exposure on whole trees

which change the wood characteristics related to twist.

The analysis of variance of the sub-data set (1) “butt log versus, top log, inner positions” did not find

wind exposure (line effect) to be significant for the variation of twist in these battens. Wald tests found

“log position”, the orientation with respect to the wind within the log and the interaction between these

two factors to be significant for the variation in twist (p=0.05). Twist increased with height (butt log to

top log) and with position of the batten towards the wind-facing half of the log. Wald tests for the sub-

data set (2) (butt log, inner versus outer position) also showed the effects of cross-sectional position of

the battens on the variation of twist to be significant (log transformed data, p=0.05). Twist decreased

from the inner position to the outer position in the cross section from juvenile to mature wood. It also

slightly increased from leewards to windwards. However, the difference between these two positions

was not as large as between butt and top log. Therefore, the structure of juvenile wood (inner position

butt log, top logs) seems to have a higher disposition to twist than mature wood.

0

5

10

15

20

25

30

35

40

45

butt c

entra

l

butt i

nner

leeward

s

butt o

uter le

eward

s

butt i

nner

windward

s

butt o

uter w

indward

s

top in

ner le

eward

s

top o

uter le

eward

s

top i

nner

windward

s

top o

uter w

indward

s


twis

t [m

m] -

mea

n +/

- sta

ndar

d er

ror

10 m30 m50 m90 m

Figure 46: Variation of twist

These findings may be interpreted as follows: the higher wind exposure for the trees in line 1 did not

change the wood formation in such a way as to cause general more twist. The differences in twist

between the windwards and the leewards halves of the logs suggest that the local stress distribution in

the cross section and within the stem during wind loading seems to be more important for modifications

of the wood structure than overall wind exposure. As battens cut out of top logs also show a large twist,

the deformation could be related both to the proportion of juvenile and compression wood in these

battens. Both wood types are characterised by a low microfibril angle, which causes large shrinkage

during the drying process. In combination with grain angle this could be the reason for the large twist

values measured.

62

4.4.3.2 Bow

The bow describes the deformation of the batten over the flat face (Figure 8). Bow takes place when

uneven shrinkage of wood occurs on the two flat surfaces of a batten during wood drying. The tested

battens showed individual bow values between 0 mm and 35 mm, the mean values varied between 1mm

and 13.5mm with a large variation within each group (Figure 47). The analysis of variance found a

significant effect of the log position for the variation of bow in the entity of the data set. An interaction

between line and cross-sectional position of the log (inner, outer) was also found to be significant

(p=0.05) (Appendix 17). The interaction effect is probably due to the large differences in bow for the

battens from line 1 and line 3 from the top outer leewards position, and the high values for battens from

top inner leewards position in line 4. ANOVA analysis found the values of bow to be significantly

higher for battens from the top logs than from the butt logs in line 3 and line 4. The more exposed lines

1 and 2 showed a higher mean bow for the butt battens, but due to the large variation the means were

not significantly different.

0

2

4

6

8

10

12

14

16

butt c

entra

l

butt i

nner

leeward

s

butt o

uter le

eward

s

butt i

nner

windward

s

butt o

uter w

indward

s

top in

ner le

eward

s

top o

uter le

eward

s

top i

nner

windward

s

top o

uter w

indward

s


bow

[mm

] - m

ean

+/- s

tand

ard

erro

r

10 m30 m50 m90 m

Figure 47: Variation of bow

63

64

The detailed analysis of the sub-data set (1) “butt versus top, inner positions” found the log position, and

line-by-log and orientation with respect to wind-by-log interactions to have a significant influence on

the variation of the bow (log transformed data, p=0.05). The derived model predicted a small decrease

in bow from line 1 to line 4 (exposed to sheltered), and an increase from butt log to top log battens. Bow

also increased from leewards orientation to windwards orientation. However, the interaction effects

modified the bow in a way that the “top windwards” position is slightly reduced in bow in comparison

to “butt leewards”. The line log interaction on the other hand showed an increase in bow towards the top

battens from line 4.

Wald analysis of the subset (2) “butt, inner position versus outer position” showed that the wind

exposure on the whole tree (line effect) had a significant influence on the variation of bow for battens

from the butt logs (p=0.05, log transformed data). Orientation with respect to wind within the cross

section or position relative to the pith did not explain variation in the bow.

These findings indicate that bow seems not to be influenced by the variation of wood structure found at

the same stem height. Varying wood structure due to reaction wood or juvenile wood in comparison to

normal wood did not change the bow of the battens. However, the differences in wood structure

between battens from the inner parts of the butt logs and battens from the top logs seem to cause distinct

differences in bow.

4.4.3.3 Spring

Uneven shrinkage of the wood on the narrow faces of a batten (Figure 8) causes the deformation type

called “spring”. Figure 48 presents the variation of the mean values of spring recorded for the different

batten positions within the logs. The means varied between 1.5mm and 6.0mm with a large variance

within each tested group. In general, battens from line 1 had the most severe spring developed except

for the central positions created when the pith was boxed. However, due to the large variation no

significant differences of the means could be found (p=0.05). The analysis of variance showed that the

log position and an interaction between line, log, orientation with respect to wind and batten position

within the cross section had a significant influence on the variation of spring testing for the entire data

set. (Appendix 17).

0

2

4

6

8

10

12

butt c

entra

l

butt i

nner

leeward

s

butt o

uter le

eward

s

butt i

nner

windward

s

butt o

uter w

indward

s

top in

ner le

eward

s

top o

uter le

eward

s

top i

nner

windward

s

top o

uter w

indward

s


sprin

g [m

m] -

mea

n +/

- sta

ndar

d er

ror

10 m30 m50 m90 m

Figure 48: Variation of spring

The detailed analysis of the sub data sets (1) “butt versus top, inner position” and (2) “butt log, inner

versus outer position” identified the particular position characteristics of the data sets to be important for

the variation in spring (p=0.05, square root transformed data). The spring increased for battens from the

top logs, t-tests found the means to be significantly different for the sheltered lines 3 and 4. For battens

from the butt logs, the spring was significantly smaller for battens cut from the outer cross-sectional

position compared to those from close to the pith.

These results suggest that the wood structure which characterises juvenile wood might be most

responsible for spring deformation. However, modifications in the wood structure of juvenile wood in

the top logs might be due to increased wind exposure in the crowns. Differences in the wood structure

due to the presence of compression wood or normal wood did not alter the spring significantly.

65

4.4.4 Structural characteristics of the battens: density, juvenile wood, compression wood, grain angle, knottiness

4.4.4.1 Density

The air dry batten density varied in a broad range around 400 kg/m³ (Figure 49) which is about the same

value that Brazier&Mobbs (1993) reported for Sitka spruce from Kilmichael Forest [453 kg/m³

respectively 426 kg/m³ for 1.6m spacing respectively 1.7m spacing] and slightly higher than the values

cited in the literature (390 kg/m³) (Harding, 1988). For each batten position except “butt inner

windwards” and “top outer leewards” the density seems be highest for the battens from line 1. The butt

battens in general showed a smaller density. These results correspond with the findings for fresh and air-

dry discs (Figure 22, Figure 23). This is probably due to a higher proportion of high density

compression wood for this line (Figure 23, Figure 51).

The statistical analysis of the variation showed a significant effect of the main factors “exposure” (line),

“log position” (butt, top), the “wind orientation within the log” and the “position of the batten in the

cross section” (close to pith or periphery) and some of the interactions between the main factors.

Appendix 18). However all these effects did not explain more than 18% of the total variance of the

batten density.

0

100

200

300

400

500

600

butt c

entra

l

butt i

nner

leeward

s

butt o

uter le

eward

s

butt i

nner

windward

s

butt o

uter w

indward

s

top in

ner le

eward

s

top o

uter le

eward

s

top i

nner

windward

s


batte

n de

nsity

[kg/

m³]

- mea

n +/

- sta

ndar

d er

ror

10 m30 m50 m90 m

Figure 49: Variation of air dry density (battens)

66

4.4.4.2 Juvenile wood

Juvenile wood is known to be an important factor for timber quality as its cell wall structure and density

properties strongly differ from mature wood. It causes serious deformation due to uneven shrinkage

during the drying process and reduces wood strength due to short fibre length and low microfibril angle.

Juvenile wood becomes particularly important when silvicultural practice supports a vigorous early

growth of young trees in wide spacing. For this project it was defined to consist of the first 12 years

developed around the pith.

Figure 50 shows the variation of the mean proportion of juvenile wood in the battens. As follows from

the cutting scheme, the inner battens and the top battens consisted of substantially larger proportion of

juvenile wood than the outer battens. The proportion of juvenile wood varied between 6% and 96%,

with statistical significant differences between the outer positioned battens, the inner butt battens and

the top positioned battens. There was no significant difference in the means of juvenile wood percentage

between the different lines.

0

20

40

60

80

100

120

butt c

entra

l

butt i

nner

leeward

s

butt o

uter le

eward

s

butt i

nner

windward

s

butt o

uter w

indward

s

top in

ner le

eward

s

top o

uter le

eward

s

top i

nner

windward

s

top o

uter w

indward

s


mea

n ju

veni

le w

ood

[%] -

mea

n +/

- sta

ndar

d er

ror

10 m30 m50 m50 m

Figure 50: Variation of juvenile wood

67

4.4.4.3 Compression wood

The most important factor in wood structure with respect to wind exposure is compression wood

(Seeling, 1999). It is known to reduce timber quality due to its different cell wall chemistry and cell wall

structure. The high lignin content and low microfibril angle are responsible for a decrease in mechanical

strength and a disposition to warp. The analysis of the presence and proportion of compression wood

focussed on material sampled from the most different exposure situations on site: line 1 (most exposed)

and line 4 (most sheltered).

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

butt o

uter le

eward

s

butt i

nner

leeward

s

butt c

entra

l

butt i

nner

windward

s

butt o

uter w

indward

s

top ou

ter le

eward

s

top i

nner

leeward

s

top i

nner

windward

s

top o

uter w

indward

s


com

pres

sion

woo

d [r

atio

of b

atte

n su

rfac

e] -

mea

n +/

- sta

ndar

d er

ror

10 m90 m

Figure 51: Variation of the mean compression wood ratio

The variation of compression wood ratio on the batten surface is illustrated in Figure 51. The means

varied between 25% and 83% for the different batten positions in the stem with the highest values

recorded for battens from line 1 in the positions “butt centre” and “top inner leewards”. The overall

mean of compression wood in line 1 was significantly higher than the amount of compression wood

found for line 4 (student-t test). However, statistical analysis showed a large variance of compression

wood proportion within each group. Thus the proportion of compression wood in battens from the wind-

facing half of the log are significantly higher in line 1 than in line 4 (Appendix 19).

68

69

The distribution of compression wood in the butt log from line 1 showed a more heterogeneous

orientation of the compression wood, in particular in the inner log parts, as is reflected by its high

compression wood ratio for battens from position “inner windwards”.

Analysis of the variance of all battens found the direction relative to the wind of the batten position had

a significant effect on the variation of compression wood ration (p=0.05), whereas line and log position

effect (top or butt) were not found to be significant (pline=0.08, plog=0.055). However, the orientation

with respect to the wind only accounts for 21.6% of the variance (Appendix 19).

For further analysis we split the data set for battens solely from the butt logs of both lines (I) and for

battens from the inner core in butt and top logs (II). Wald tests were used to analyse these data sets

separately for effect of exposure (line), log position, orientation relative to the wind and position in the

cross section. For battens from the inner positions of butt and top log, the effect of the orientation of the

battens with respect to the wind is significant for the amount of compression wood, whereas line effect

and line-by-log interactions are found to be just not significant. In contrast, for the battens from butt

logs the variation of compression wood showed a significant effect of exposure (line), but no effect of

the orientation to the direction relative to the wind, the position of the batten in relation to the pith or

any significant interactions between these components.

4.4.4.4 Grain angle

In combination with juvenile wood and compression wood, the grain angle is also known to cause

severe distortion by twist during the drying process. The tested battens from line 1 and line 4 varied

widely in mean grain angle between 0° (straight fibres) and 5°. The analysis of variance showed that

none of the tested factors “line”, “log position”, “orientation relative to the wind” or “position in the

cross section” (close to pith or periphery) had a significant effect to explain the variation of grain angle.

Due to the large variation within each group, the differences of the means between the lines and

between the different batten positions were found to be not significant (ANOVA analysis, t-tests,

p=0.05).

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

butt c

entra

l

butt i

nner

leeward

s

butt o

uter le

eward

s

butt i

nner

windward

s

butt o

uter w

indward

s

top in

ner le

eward

s

top o

uter le

eward

s

top i

nner

windward

s

top o

uter w

indward

s


grai

n an

gle

[deg

ree]

- m

ean

+/- s

tand

ard

erro

r

10 m90 m

Figure 52: Variation of grain angle

4.4.4.5 Knottiness

Figure 53: Variation of mean knot diameter

0

2

4

6

8

10

12

14

16

10 90


mea

n kn

ot d

iam

eter

[mm

] - m

ean

+/- s

tand

ard

erro

r

inner faceedge 1outer faceedge 2

70

Knots are known to weaken the wood structure and to reduce wood strength as they alter the fibre

direction on a batten. The knot diameter and knot area on the batten surface also determine whether

battens can be used for high quality purposes. In this project, the visual assessment of batten knots was

undertaken on a sub-sample of 6 trees each from line 1 and line 4 in order to identify the importance of

knots for the most exposed and most sheltered exposure chosen on the site. Only substantial knots were

recorded which were known to weaken wood strength.

The mean knot diameter as assessed on the broad and the narrow faces of each batten varied in a wide

range up to 58 mm, the lower limits for recording were set at 38 mm for a single knot and at 15 mm for

a number of knots within 150 mm distance. Figure 53 shows the variation of mean knot diameter as

recorded on the four different faces. There was no particular trend for knot diameter on battens from

different positions within the tree. Due to the large variation within each group, no statistically

significant differences in the means between line 1 and line 4 could be found (p=0.05).

0

2

4

6

8

10

12

14

10 90


knot

are

a [%

sur

face

bat

ten]

- m

ean

+/- s

tand

ard

erro

r

butt innerbutt outertop inner

Figure 54: Variation of knot area on batten surface

The mean knot area of the central part of each batten varied between 2% and 7%. In a similar manner to

the knot size there was no obvious difference found between line 1 and line 4. This partly corresponds

with the findings on the branchiness of the logs (section 4.3). The logs did show a slightly decrease in

branch diameter from line 1 to line 4 due to decline in light availability and self pruning. However, the

knot diameter strongly depends on the absolute position of the batten and where relative to whorl the

piece was cut.

71

72

5 Summary

The overall objective of this project was to investigate the influence of wind exposure on tree growth and wood characteristics. The investigations linked tree characteristics in the forest, conversion at the saw mill and quality assessment of resulting battens in order to follow the complete chain from the forest to the product. This allowed a precise judgement on the effect of wind exposure on timber quality with respect to the potential high quality utilisation.

The methodology considered three different levels: tree, saw log and batten. 60 trees (15 each grown under different wind exposure from 4 lines at 10m, 30m, 50m, 90m distance from the stand edge) were selected and characterised by their size, shape and their mechanical properties while standing (MOEstruct, swaying frequency). 178 logs (butt, mid and top) were cross cut from these trees and assessed by their outer form (taper, ovality) and internal structure (ring width, eccentricity of pith, juvenile wood) in a procedure similar to the log grading standard prEN 1927-1. Top logs and butt logs were converted into battens of size 5x10x400 mm (fresh) using a cutting scheme which separated battens from the windward and the leeward sides of the stem and between juvenile and mature wood. Stress grading, static bending tests and visual assessment of distortion and wood structure were undertaken on the battens. The separation of battens from different stem positions allowed a fine assessment of the effect on wind exposure within the stem.

At the tree level it appears that wind exposure affects the outer shape of the tree to a larger degree than it modifies the mechanical properties of the whole stem. There appeared to be a trend for stems to grow stiffer in the more sheltered locations, but trees varied much more individually within one line than did the mean of each line. Close to the edge, the trees grew shorter and thicker. This phenomenon is known as thigmomorphogenesis (Telewski, 1995) which is controlled by growth regulators. Tree stability is largely controlled by the outer shape of the tree and to a smaller degree by the stem material properties (Brüchert et al., 2000, Gardiner et al 2000). The shorter, more tapered stems at the stand edge are better adapted to wind and these trees will sway less, which might help to prevent the root system being weakened. However, it is quantitatively not known at the moment, how much the movement of the root plate influences the development of the tree form, but adaptive root development as a result of different loading on both sides of a trunk has been reported by Nicoll & Ray (1996) and Watson (2000).

The classification of the logs also showed no significant influence of the different levels of wind exposure on the log quality. The main factor for log quality was the size of branches (61%). Only 10% of the log were graded due to the eccentricity of the pith. However, the grading of the logs was undertaken without detailed measurements of the log straightness which is recognised as an important characteristic for log quality both in prENV 1927 and FC log grading rules.

In contrast to the “homogenous” appeareance of the trees and logs grown under different wind exposure, we found a significant difference in the growth pattern of the stems and the variaton of wood structure in the cross section. The trees close to the edge grew increasingly more eccentric with age in comparison to the more sheltered trees. We also found a larger proportion of compression wood in trees growing close to the exposed edge than in more sheltered trees. The distribution of compression wood

73

in the cross-section showed a more heterogeneous orientation in the exposed trees, in particular in the inner log parts. This is probably due to larger stem deflections in all directions at the stand edge. However, all trees showed a relatively high proportion of compression wood at this site indicating that overall it was very wind exposed.

The generally small differences in tree and log performance between the four different levels of wind exposure are reflected by generally small differences in the mechanical and physical properties of the battens. However, machine stress grading classified 45% of battens from the most exposed trees as not suitable for C24/C16 grades whereas only 25% were rejected for the more sheltered trees. The detailed analysis of all tested properties (MOEstat, MOR, distortion) showed a much stronger influence of the position in the stem where the batten had been cut from than the influence of wind exposure to the tree. Whether the batten was cut from the butt log or top log or from the windwards or the leewards side or from the juvenile or the mature wood accounted for larger differences in wood structure and performance than did the wind exposure on the tree.

The internal variation of the wood structure in the stem (windwards, leewards, juvenile wood, mature wood, butt top) appeared to be important for the batten performance. These findings could have practical consequences for wood processing such as cutting schemes and automatic sorting based on the variation of the internal structure of the logs. Automatic sorting would allow collection of products with similar performance in order to form homogenous packages which would be easier to handle in ongoing processing.

The results on external characteristics, wood structure and performance of the end products show a large individual reaction of the tree growth situation which is reflected by the large variation in each tested characteristic. An obvious growth reaction of the trees to the influence of wind was the development of eccentric cross sections due to the formation of reaction wood which occurred in a significantly higher proportion in the exposed trees. For the tested material, the presence of compression wood did not alter the performance of the battens in a significant way. The absolute difference in wind exposure which effected the tree growth was not large enough to cause a general difference in wood properties integrated over the stem. However, the tested material showed generally the features of strong exposure such as the presence of compression wood in almost all battens. To separate out the effects of wind exposure completely, it would be necessary to investigate other sites which have a different wind regime.

74

6 References

ANONYMUS (1998): ENV 1927-1: Qualitative Classification of softwood round wood Part 1: Spruces and firs.

BRAZIER J.D., MOBBS I.D. (1993): The influence of Planting Distance on Structural Wood Yields of Unthinned Sitka Spruce. - Forestry Vol 66 No 4: 333-352

BRÜCHERT F., SPECK T., BECKER G. (2000): The mechanics of Norway spruce [Picea abies (L.) Karst]: the mechanical properties of standing trees from different thinning regimes. - Forest Ecology and Management 135, 45-62.

EDWARDS P.N., CHRISTIE J.M. (1981): Yield Models For Forest Management. - Forestry Commission Booklet 48. Forestry Commission, Farnham.

FAIR CT 1996-1915 STUD Final Report, The Building Research Establishment, oral communication.

FAIR CT 98-5038 (1999) “The Influence of the site factor wind exposure on wood quality”. - Annual report.

FORESTRY COMMISSION (1993): Classification and presentation of softwood sawlogs. – Forestry Commission Field Book 9. HMSO, London.

GARDINER B.A. (1989): Mechanical Characteristics of Sitka Spruce. - Forestry Commission Occasional Paper 24. Forestry Commission Publications. Edinburgh.

GARDINER B.A, PELTOLA H., Kellomäki S. (2000): Comparison of two models for predicting the critical wind speeds required to damage coniferous trees. - Ecological Modelling 129: 1-23.

HARDING T. (1988): British Softwoods – Properties and Uses. - Forestry Commission Bulletin 77.

41p.

MACDONALD E., MOCHAN S., CONNOLLY T. (2001): Protocol for Stem Straightness Assessment

in Sitka Spruce. - Forestry Commission Information Note 39.

LINDSTROM H. (2000): Intra-tree models of basic density in Norway spruce as an input to simulation software. - Silva Fennica 34 (4): 411- 421.

NICOLL B.C., RAY D. (1996): Adaptive growth of tree root systems in response to wind action and site conditions. - Tree Physiology 16: 899-904.

QUINE C.P., WHITE I.M.S. (1993): Revised windiness scores for the windthrow hazard classification: the revised scoring method. - Forestry Commission Research Information Note 230. Forestry Commission Publications. Edinburgh.

SEELING U. (1999): Einfluss von Richtgewebe (“Druckholz”) auf Festigkeit und Elastizität des Fichtenholzes. - Holz als Roh- und Werkstoff 57 (2): 81-91.

STACEY G.R., BELCHER R.E., WOOD, C.J., GARDINER B.A (1994): Wind Flows and Forces in a Model Spruce Forest. - Boundary - Layer Meteorology 69: 311-334.

TELEWSKI F.W. (1995): Wind-induced physiological and developmental responses in trees. - In: Coutts, M.P., Grace, J. (eds.). Wind and Trees. Cambridge: 237-263.

WATSON A. (2000): Wind-induced forces in the near-surface lateral roots of radiata pine. - Forest Ecology and Management 135: 133-142.

76

Appendix 1: Statistical analysis of the variation of MOEstruct

Descriptive statistics: MOEstruct

LINE N mean s.e. s.d. min max 1 117 5.26 0.17 1.81 2 12 2 120 5.41 0.13 1.41 2 10 3 113 5.08 0.13 1.38 2 9 4 113 5.13 0.12 1.31 2 8

ANOVA MOEstruct

Sums of square df mean of squares F sig. Between the groups 7.882 3 2.627 1.182 0.316 Within the groups 1019.991 459 2.222 Total 1027.873 462

Post-Hoc test: Scheffé

(I) LINE (J) LINE

mean difference

(I-J) s.e sig. 95%-conf. lower

limit upper limit

1 2 -0.16 0.19 0.881 -0.70 0.39 3 0.18 0.20 0.845 -0.37 0.73 4 0.13 0.20 0.936 -0.42 0.68 2 1 0.16 0.19 0.881 -0.39 0.70 3 0.34 0.20 0.400 -0.21 0.88 4 0.29 0.20 0.546 -0.26 0.83 3 1 -0.18 0.20 0.845 -0.73 0.37 2 -0.34 0.20 0.400 -0.88 0.21 4 -5.06E-02 0.20 0.996 -0.61 0.51 4 1 -0.13 0.20 0.936 -0.68 0.42 2 -0.29 0.20 0.546 -0.83 0.26 3 5.06E-02 0.20 0.996 -0.51 0.61 *significantly different (p=0.05)

77

Pearson’s correlation coefficients mean MOEstruct, tree

N coefficient sign

Johann-Zahlmean 60 0.282* 0.029

tree height [m] 60 0.147 0.264

diameter [m] 60 -0.195 0.136

stem ovalitymean [/] 60 -0.166 0.204

log taper [cm/m length] -0.154 0.239

angle spiral grain [°] 52 0.004 0.979

relative crown length [/] 60 -0.290* 0.025

height 1. dead whorl [m] 60 -0.070 0.595

height 1. Green branch [m] 60 0.240 0.065

height 1. Green whorl [m] 60 0.276* 0.032

relative height 1. dead whorl [/] 60 -0.071 0.590

relative height 1.green branch [/] 60 0.243 0.061

relative height 1.green whorl [/] 60 0.290* 0.025

height largest branch mass [m] 60 0.321* 0.012

vertical crown projection area [m²] 60 -0.275* 0.034

horizontal crown projection area sailing area [m²] 60 -0.161 0.218

crown max. spread [m] 60 -0.051 0.697

crown min. spread [m] 60 -0.280* 0.030

crown eccentricity [max/min] [/] 60 0.311* 0.016

crown mass [kg] 60 -0.229 0.078

canopy volume [m³] 60 -0.212 0.104

crown density [kg/m³] 60 0.040 0.761 ** the correlation is significant (p= 0,01) (2-sided) * the correlation is significant (p= 0,05) (2-sided)

78

Wald tests for fixed effects “absolute height“ and “line“

Fitted model Tested model Fixed term Wald statistic d.f. Wald statistic d.f. Absolute height 481.7* 1 484.6* 1 Line 11.1* 3 11.1* 3 height.line 5.8 3 *significantly different (p=0.05) Statistical model

Effects for constant 8.208 s.e. 0.2746 Effects for height -0.1933 s. e. 0.008793 Effects for line 1 2 3 4 0.0000 0.2913 0.0883 1.1109 s.e.d. average 0.3730 maximum 0.3736 minimum 0.3723 Appendix 2: Test for differences in heterogeneity of MOEstruct

χ²− test

MOEstruct variation line

observed N

expected N residual

none 1 61 65.8 -4.8 2 71 65.8 5.3 3 65 65.8 -0.8 4 66 65.8 0.3 total 263

small 1 25 24.0 1.0 2 29 24.0 5.0 3 20 24.0 -4.0 4 22 24.0 -2.0 total 96

large 1 16 8.0 8.0 2 5 8.0 -3.0 3 6 8.0 -2.0 4 5 8.0 -3.0 total 32

79

Statistics for χ²− test MOEstruct variation Line None χ² 0.772 df 3 sig. 0.856 Small χ² 1.917 df 3 sig. 0.590 Large χ² 10.750 df 3 sig. 0.013

Appendix 3: Statistical analysis of tree swaying frequency

Descriptive statistics: swaying frequency

LINE N mean s.e. s.d. min max

1 15 .268523 1.73277E-02 6.71097E-02 .1281 .4051 2 15 .246517 7.06384E-03 2.73581E-02 .2011 .2842 3 15 .230630 7.81069E-03 3.02507E-02 .1649 .2859 4 15 .218367 1.13609E-02 4.40005E-02 .1453 .2862 ANOVA: swaying frequency, accumulated analysis of variance Change d.f s.s. m.s. v.r. F pr. + height 1 0.049562 0.049562 44.83 <0.001 + diameter 1 0.019768 0.019768 17.88 <0.001 + line 3 0.000279 0.000093 0.08 0.968 + ovality 1 0.000076 0.000076 0.07 0.795 + MOEstruct 1 0.001042 0.001042 0.94 0.337 + rclength 1 0.001932 0.001932 1.75 0.193 + hlbmass 1 0.000050 0.000050 0.05 0.833 + vcpa 1 0.007999 0.007999 7.24 0.010 + cmaxA 1 0.000601 0.000601 0.54 0.465 + cminA 1 0.000021 0.000021 0.02 0.891 + eccent 1 0.002416 0.002416 2.19 0.147 + cmass 1 0.003754 0.003754 3.40 0.073 + sailarea 1 0.001098 0.001098 0.99 0.325 + cvolume 1 0.000210 0.000210 0.19 0.665 + cdensity 1 0.000235 0.000235 0.21 0.648 + jz 1 0.000191 0.000191 0.17 0.679 Residual 41 0.045328 0.001106 Total 59 0.134563 0.002281

80

Accumulated analysis of variance Change d.f. s.s. m.s. v.r. F pr. + height 1 0.049562 0.049562 43.61 <0.001 + diameter 1 0.019768 0.019768 17.40 <0.001 + vcpa 1 0.001594 0.001594 1.40 0.241 Residual 56 0.063638 0.001136 Total 59 0.134563 0.002281

ANOVA: swaying frequency, summary of analysis

Source of variation d.f.(m.v.) s.s. m.s. v.r. cov.ef. F pr. Line 3 0.000279 0.000093 0.08 0.87 0.972 covariates 2 0.048493 0.024247 20.16 <0.001

height 1 0.033350 0.033350 27.73 <0.001 dbh 1 0.015143 0.015143 12.59 <0.001

Residual 54 0.064953 0.001203 1.68 Total 59 0.134563

Tables of means line 1 2 3 4. total 0.2433 0.2398 0.2431 0.2379 0.2410

Standard errors of differences of means, least significant differences of means (5% level) rep. d.f. s.e.d. l.s.d. line 15 54 0.01354 0.02715

Statistical model

estimate s.e. t (57) t pr.

Constant 0.3960 0.0561 7.06 p<0.001

Height -0.01429 0.00186 -7.69 p<0.001

Diameter at 1.3m 0.685 0.165 4.16 p<0.001

f=0.3960-0.01429*h+0.685*dbh

81

Appendix 4 : Statistical analysis of variation of fresh disc density

Descriptive statistics: fresh disc density


1 88 793.2932 11.5644 108.4841 564.80 1062.40 2 84 772.3702 9.9332 91.0393 592.60 970.90 3 89 747.9382 9.5508 90.1023 559.50 985.20 4 85 756.6282 11.9620 110.2843 492.10 1054.10

ANOVA

Sums of square df mean of squares F sig. Between the groups 104640.916 3 34880.305 3.460 0.017 Within the groups 3447883.874 342 10081.532 total 3552524.790 345 Post-Hoc test: Scheffé

(I) LINE (J) LINE

mean difference

(I-J) s.e sig. 95%-conf. lower

limit upper limit

1 2 20.9229 15.3160 0.601 -2.1068 63.9527 3 45.3550* 15.0943 0.030 2.9481 87.7619 4 36.6649 15.2699 0.126 -6.2351 79.56502 1 -20.9229 15.3160 0.601 -3.9527 22.1068 3 24.4320 15.2740 0.466 -8.4795 67.3436 4 15.7420 15.4475 0.792 -7.6570 59.14113 1 -45.3550* 15.0943 0.030 -7.7619 -2.9481 2 -24.4320 15.2740 0.466 -7.3436 18.4795 4 -8.6900 15.2277 0.955 -1.4715 34.09154 1 -36.6649 15.2699 0.126 -9.5650 6.2351 2 -15.7420 15.4475 0.792 -9.1411 27.6570 3 8.6900 15.2277 0.955 -4.0915 51.4715*significantly different (p=0.05)

82

Wald tests for fixed effects “line“ and “absolute height“

Fitted model Tested model Fixed term Wald statistic d.f. Wald statistic d.f. Line 3.9 3 5.3 3 Absolute height 72.3* 1 93.7* 1 Absolute height (sq.) 63.7* 1 Absolute height (cube) 12.5* 1 line.absolute height 7.3 3 11.7* 3 line.absolute height (sq) 0.5 3 line.absolute height (cube) 6.8 3 *significantly different (p=0.05) Statistical model

effects for constant 718.0 s.e. 10.92 effects for absolute height 5.807 s.e. 0.6915

Appendix 5 : Statistical analysis of variation of air dried disc density

Descriptive statistics: air-dry disc density


1 75 445.98862 5.52135 47.81633 360.727 555.996

2 75 414.67290 5.36958 46.50191 323.145 546.609

3 77 405.25587 5.30696 46.56842 333.971 564.659

4 72 413.36858 5.55900 47.16966 339.399 603.338

ANOVA Sums of square df mean of squares F sig.

Between the groups 72675.874 3 24225.291 10.961 .000 Within the groups 652001.649 295 2210.175 total 724677.523 298

83

Post –hoc-test: Scheffé

(I) LINE (J) LINE mean

difference (I-J) s.e sig. 95%-conf. lower limit upper limit

1 2 31.31572* 7.67711 .001 9.73003 52.90140 3 40.73275* 7.62709 .000 19.28769 62.17781 4 32.62004* 7.75667 .001 10.81066 54.42942 2 1 -31.31572* 7.67711 .001 -2.90140 -9.73003 3 9.41703 7.62709 .677 -2.02803 30.86210 4 1.30433 7.75667 .999 -0.50505 23.11371 3 1 -40.73275* 7.62709 .000 -2.17781 -9.28769 2 -9.41703 7.62709 .677 -0.86210 12.02803 4 -8.11271 7.70717 .775 -9.78291 13.55750 4 1 -32.62004* 7.75667 .001 -4.42942 -10.81066 2 -1.30433 7.75667 .999 -3.11371 20.50505 3 8.11271 7.70717 .775 -3.55750 29.78291 *significantly different (p=0.05)

Wald tests for fixed effects “absolute height“ and “line“

Fixed term Wald statistic d.f. Absolute height 13.8 1 Line 15.5 3 height.line 8.0 3 Statistical model Effects for constant 419.4 s.e. 12.36

Effects for height 2.870 s. e. 0.9579

Effects for line 1 2 3 4 0.00 -3.80 -29.60 -34.59 s.e.d. average 16.94 maximum 17.34 minimum 16.55 a.v.d. 287.2 Effects for height.line 1 2 3 4 0.000 -3.117 -1.407 -0.098 s.e.d. average 1.241 maximum 1.297 minimum 1.183 a.v.d. 1.542

84

Appendix 6: Analysis of variance of radial growth in leewards and windwards direction of the stem

Variate: yr[5] difference between radiusleewards and radiuswindwards

Source of variation d.f.(m.v.) s.s. m.s. v.r. F pr. Line 3 0.0001231 0.0000410 0.26 0.857 Residual 54(2) 0.0086445 0.0001601 Total 57(2) 0.0087657

Tables of means

line 1 2 3 4. total

0.0078 0.0079 0.0044 0.0063 0.0066 Standard errors of differences of means, least significant differences of means (5% level) rep. d.f. s.e.d. l.s.d. line 15 54 0.00462 0.00926



Tables of means

line 1 2 3 4. total




Tables of means

line 1 2 3 4. total


85

Variate: yr[20] difference between radiusleewards and radiuswindwardsSource of variation d.f.(m.v.) s.s. m.s. v.r. F pr. Line 3 0.008467 0.002822 1.37 0.261 Residual 54(2) 0.111001 0.002056 Total 57(2) 0.119136

Tables of means line 1 2 3 4. total




Tables of means

line 1 2 3 4. total


Appendix 7: Statistical analysis of the branchiness ofthe saw logs

Descriptive statistics: thickest branch per log [mm]

Log position butt, mid, top LINE N mean s.e. s.d. min max

b 1 14 33.3214 3.1122 11.6448 17.00 61.50 2 15 31.2533 2.2284 8.6304 15.00 46.00 3 15 27.7333 2.1962 8.5060 17.00 46.00 4 15 24.9667 1.4626 5.6646 17.00 35.00

m 1 14 42.1429 3.4575 12.9369 23.00 74.00 2 14 38.6214 3.5891 13.4293 22.20 72.00 3 15 41.0467 3.5106 13.5964 24.00 65.70 4 15 37.4000 1.6791 6.5033 30.00 52.00 t 1 15 55.3733 4.3022 16.6623 37.00 103.60 2 15 45.0133 2.6376 10.2153 30.50 71.00 3 15 50.4200 2.6773 10.3691 32.00 79.00 4 15 48.5000 2.8847 11.1724 34.00 75.00

86

ANOVA Log position butt, mid, top

Sums of square df

mean of squares F sig.

b between the groups 601.980 3 200.660 2.586 0.062 within the groups 4267.748 55 77.595 total 4869.727 58

m between the groups 205.988 3 68.663 0.482 0.697 within the groups 7700.355 54 142.599 total 7906.343 57 t between the groups 840.687 3 280.229 1.825 0.153 within the groups 8600.551 56 153.581 total 9441.237 59

ANOVA

LINE Sums of square df


1.00 between the groups 3584.464 2 1792.232 9.161 .001 within the groups 7825.387 40 195.635 total 11409.852 42 2.00 between the groups 1422.306 2 711.153 6.014 .005 within the groups 4848.198 41 118.249 total 6270.504 43 3.00 between the groups 3898.945 2 1949.473 16.035 .000 within the groups 5106.235 42 121.577 total 9005.180 44 4.00 between the groups 4158.078 2 2079.039 31.310 .000 within the groups 2788.833 42 66.401 total 6946.911 44

87

Post –hoc-test: Scheffé

Log position Butt, Mid, Top (I) LINE (J) LINE

mean difference (I-J) s.e sig. 95%-conf.

lower limit upper limitb 1.00 2.00 2.0681 3.2735 .940 -7.3727 11.5088 3.00 5.5881 3.2735 .413 -3.8527 15.0288 4.00 8.3548 3.2735 .102 -1.0860 17.7955 2.00 1.00 -2.0681 3.2735 .940 -11.5088 7.3727 3.00 3.5200 3.2165 .754 -5.7566 12.7966 4.00 6.2867 3.2165 .293 -2.9899 15.5632 3.00 1.00 -5.5881 3.2735 .413 -15.0288 3.8527 2.00 -3.5200 3.2165 .754 -12.7966 5.7566 4.00 2.7667 3.2165 .863 -6.5099 12.0432 4.00 1.00 -8.3548 3.2735 .102 -17.7955 1.0860 2.00 -6.2867 3.2165 .293 -15.5632 2.9899 3.00 -2.7667 3.2165 .863 -12.0432 6.5099 m 1.00 2.00 3.5214 4.5135 .894 -9.5031 16.5459 3.00 1.0962 4.4376 .996 -11.7094 13.9018 4.00 4.7429 4.4376 .767 -8.0627 17.5484 2.00 1.00 -3.5214 4.5135 .894 -16.5459 9.5031 3.00 -2.4252 4.4376 .960 -15.2308 10.3804 4.00 1.2214 4.4376 .995 -11.5842 14.0270 3.00 1.00 -1.0962 4.4376 .996 -13.9018 11.7094 2.00 2.4252 4.4376 .960 -10.3804 15.2308 4.00 3.6467 4.3604 .873 -8.9362 16.2295 4.00 1.00 -4.7429 4.4376 .767 -17.5484 8.0627 2.00 -1.2214 4.4376 .995 -14.0270 11.5842 3.00 -3.6467 4.3604 .873 -16.2295 8.9362 t 1.00 2.00 10.3600 4.5252 .168 -2.6835 23.4035 3.00 4.9533 4.5252 .754 -8.0902 17.9968 4.00 6.8733 4.5252 .516 -6.1702 19.9168 2.00 1.00 -10.3600 4.5252 .168 -23.4035 2.6835 3.00 -5.4067 4.5252 .700 -18.4502 7.6368 4.00 -3.4867 4.5252 .897 -16.5302 9.5568 3.00 1.00 -4.9533 4.5252 .754 -17.9968 8.0902 2.00 5.4067 4.5252 .700 -7.6368 18.4502 4.00 1.9200 4.5252 .981 -11.1235 14.9635 4.00 1.00 -6.8733 4.5252 .516 -19.9168 6.1702 2.00 3.4867 4.5252 .897 -9.5568 16.5302 3.00 -1.9200 4.5252 .981 -14.9635 11.1235 *significantly different (p=0.05)

88

Scheffé-Prozedur

LINE (I) logpos (J) logpos mean

difference (I-J) s.e sig. 95%-conf. lower limit upper limit 1.00 butt mid -8.8214 5.2866 .260 -22.2616 4.6188 top -22.0519* 5.1977 .001 -35.2662 -8.8376 mid butt 8.8214 5.2866 .260 -4.6188 22.2616 top -13.2305* 5.1977 .050 -26.4448 -1.6163E-02 top butt 22.0519* 5.1977 .001 8.8376 35.2662 mid 13.2305* 5.1977 .050 1.616E-02 26.4448 2.00 butt mid -7.3681 4.0410 .202 -17.6320 2.8958 top -13.7600* 3.9707 .005 -23.8454 -3.6746 mid butt 7.3681 4.0410 .202 -2.8958 17.6320 top -6.3919 4.0410 .297 -16.6558 3.8720 top butt 13.7600* 3.9707 .005 3.6746 23.8454 mid 6.3919 4.0410 .297 -3.8720 16.6558 3.00 butt mid -13.3133* 4.0262 .008 -23.5306 -3.0961 top -22.6867* 4.0262 .000 -32.9039 -12.4694 mid butt 13.3133* 4.0262 .008 3.0961 23.5306 top -9.3733 4.0262 .078 -19.5906 .8439 top butt 22.6867* 4.0262 .000 12.4694 32.9039 mid 9.3733 4.0262 .078 -.8439 19.5906 4.00 butt mid -12.4333* 2.9755 .001 -19.9842 -4.8825 top -23.5333* 2.9755 .000 -31.0842 -15.9825 mid butt 12.4333* 2.9755 .001 4.8825 19.9842 top -11.1000* 2.9755 .002 -18.6508 -3.5492 top butt 23.5333* 2.9755 .000 15.9825 31.0842 mid 11.1000* 2.9755 .002 3.5492 18.6508 *significantly different (p=0.05)

grade

LINE grade observed

N expected

N residual 1 B 10 14.7 -4.7 C 24 14.7 9.3 D 10 14.7 -4.7 total 44

2 B 11 14.7 -3.7 C 30 14.7 15.3 D 3 14.7 -11.7 total 44

3 B 16 15.0 1.0 C 20 15.0 5.0 D 9 15.0 -6.0 total 45

4 B 16 15.0 1.0 C 25 15.0 10.0 D 4 15.0 -11.0 total 45

89

Statistics for χ² - test - grade LINE χ² df sig. 1 8.909 2 .012 2 26.227 2 .000 3 4.133 2 .127 4 14.800 .001 χ²− test - grade

logpos grade observed

N expected

N residual butt B 36 20.0 16.0

C 22 20.0 2.0 D 2 20.0 -18.0 total 60

mid B 13 19.3 -6.3 C 39 19.3 19.7 D 6 19.3 -13.3 total 58

top B 4 20.0 -16.0 C 38 20.0 18.0 D 18 20.0 -2.0 total 60

Statistics for χ²test - grade logpos χ² df sig. butt 29.200 2 .000 mid 31.276 2 .000 top 29.200 2 .000

χ²-test - line

grade line observed

N expected

N residual B 1 10 13.3 -3.3 2 11 13.3 -2.3 3 16 13.3 2.8 4 16 13.3 2.8 total 53

C 1 24 24.8 -.8 2 30 24.8 5.3 3 20 24.8 -4.8 4 25 24.8 .3 total 99

D 1 10 6.5 3.5 2 3 6.5 -3.5 3 9 6.5 2.5 4 4 6.5 -2.5 total 26

90

Statistics for χ²test - line grade χ² df sig.

grade B 2.321 3 .509 grade C 2.051 3 .562 grade D 5.692 3 .128

Appendix 8: Statistical analysis of the mean ring width of saw log

Descriptive statistic of mean ringwidth of year [mm]

Log position butt, mid, top LINE N mean s.e. s.d. min max

b 1 15 4.3656 .1224 .4741 3.6830 5.2399 2 14 4.0750 .1147 .4291 3.2029 4.9033 3 15 4.0176 .1737 .6726 2.8289 4.8958 4 15 3.9575 .0731 .2832 3.3966 4.3529 total 59 4.1044 .0650 .4994 2.8289 5.2399

m 1 28 5.0359 .1468 .7769 3.4668 6.6867 2 26 4.7171 .1132 .5772 3.6361 5.9877 3 29 4.8049 .1705 .9183 3.2422 6.1977 4 27 4.6891 .1168 .6067 3.5450 6.0095 total 110 4.8145 .0707 .7410 3.2422 6.6867 t 1 29 5.2755 .1784 .9605 3.6130 7.0237 2 29 5.1406 .1345 .7244 3.9662 6.7276 3 30 5.4833 .2057 1.1264 3.6210 7.4752 4 30 5.1390 .1108 .6069 3.9173 6.2245 total 118 5.2605 .0809 .8788 3.6130 7.4752

ANOVA mean ringwidth of year [mm]

Log position butt, mid, top

Sums of square df


b between the groups 1.472 3 .491 2.076 .114 within the groups 12.996 55 .236 total 14.468 58

m between the groups 2.046 3 .682 1.251 .295 within the groups 57.809 106 .545 total 59.855 109 t between the groups 2.355 3 .785 1.017 .388 within the groups 88.000 114 .772 total 90.356 117

91

Post Hoc test, Scheffé-procedure Log position Butt, Mid, Top (I) LINE (J) LINE


lower limit upper limit b 1 2 .291 .181 .466 -.230 .812 3 .348 .177 .290 -.164 .860 4 .408 .177 .165 -.104 .920 2 1 -.291 .181 .466 -.812 .230 3 .057 .181 .992 -.464 .578 4 .117 .181 .935 -.404 .638 3 1 -.348 .177 .290 -.860 .164 2 -.057 .181 .992 -.578 .464 4 .060 .177 .990 -.452 .572 4 1 -.408 .177 .165 -.920 .104 2 -.117 .181 .935 -.638 .404 3 -.060 .177 .990 -.572 .452 m 1 2 .319 .201 .476 -.253 .890 3 .231 .196 .708 -.325 .787 4 .347 .199 .391 -.219 .913 2 1 -.319 .201 .476 -.890 .253 3 -.088 .199 .979 -.654 .479 4 .028 .203 .999 -.548 .605 3 1 -.231 .196 .708 -.787 .325 2 .088 .199 .979 -.479 .654 4 .116 .197 .951 -.445 .677 4 1 -.347 .199 .391 -.913 .219 2 -.028 .203 .999 -.605 .548 3 -.116 .197 .951 -.677 .445 t 1 2 .135 .231 .952 -.520 .790 3 -.208 .229 .843 -.857 .441 4 .136 .229 .949 -.513 .786 2 1 -.135 .231 .952 -.790 .520 3 -.343 .229 .526 -.992 .307 4 .002 .229 1.000 -.648 .651 3 1 .208 .229 .843 -.441 .857 2 .343 .229 .526 -.307 .992 4 .344 .227 .514 -.299 .988 4 1 -.136 .229 .949 -.786 .513 2 -.002 .229 1.000 -.651 .648 3 -.344 .227 .514 -.988 .299 * significantly different at p=0.05

92

χ²-test - line

LINE grade observed

N expected

N residual 1 A 6 14.7 -8.7 B 37 14.7 22.3 C 1 14.7 -13.7 total 44 2 A 6 21.0 -15.0 B 36 21.0 15.0 total 42 3 A 12 15.0 -3.0 B 30 15.0 15.0 C 3 15.0 -12.0 total 45 4 A 11 22.0 -11.0 B 33 22.0 11.0 total 44

Statistics for χ²test - line

LINE χ² df sig. 1 51.864 2 .000 2 21.429 1 .000 3 25.200 2 .000 4 11.000 1 .001

χ²-test - logpos

Logpos grade observed

N expected

N residual butt A 24 29.5 -5.5 B 35 29.5 5.5 total 59 mid A 8 28.5 -20.5 B 49 28.5 20.5 total 57 top A 3 19.7 -16.7 B 52 19.7 32.3 C 4 19.7 -15.7 total 59 Statistics of the test - logpos

logpos χ² df sig. butt 2.051 1 .152 mid 29.491 1 .000 top 79.763 2 .000

93

χ²-test - grade

grade line observed

N expected

N residual grade A 1 6 8.8 -2.8 2 6 8.8 -2.8 3 12 8.8 3.3 4 11 8.8 2.3 total 35 grade B 1 37 34.0 3.0 2 36 34.0 2.0 3 30 34.0 -4.0 4 33 34.0 -1.0 total 136 grade C 1 1 2.0 -1.0 3 3 2.0 1.0 total 4 Statistics of the test - line

grade χ² df sig. grade A 3.514 3 .319 grade B .882 3 .830 grade C 1.000 1 .317

Appendix 9: Statistical analysis of the spiral grain

Descriptive statistic of spiral grain [cm/m]

LINE N mean s.e. s.d. min max 1 15 4.4067 .7198 2.7876 .00 8.70 2 15 5.1133 .9596 3.7165 .00 12.30 3 15 5.1200 1.4097 5.4597 .00 21.30 4 15 3.1333 .9359 3.6247 .00 10.50 ANOVA spiral grain [cm/m]

spiral grain [cm/m]

Sums of square df


between the groups 39.363 3 13.121 .813 .492 within the groups 903.424 56 16.133 total 942.787 59

94

Post Hoc test, Scheffé-procedure spiral grain [cm/m] (I) LINE (J) LINE


lower limit upper limit 1 2 -.7067 1.4666 .972 -4.9341 3.5208 3 -.7133 1.4666 .971 -4.9408 3.5141 4 1.2733 1.4666 .860 -2.9541 5.5008 2 1 .7067 1.4666 .972 -3.5208 4.9341 3 -6.6667E-03 1.4666 1.000 -4.2341 4.2208 4 1.9800 1.4666 .613 -2.2474 6.2074 3 1 .7133 1.4666 .971 -3.5141 4.9408 2 6.667E-03 1.4666 1.000 -4.2208 4.2341 4 1.9867 1.4666 .610 -2.2408 6.2141 4 1 -1.2733 1.4666 .860 -5.5008 2.9541 2 -1.9800 1.4666 .613 -6.2074 2.2474 3 -1.9867 1.4666 .610 -6.2141 2.2408 * significantly different at p=0.05 ANALYSIS OF VARIANCE spiral grain [degree] SOURCE of variation

df s.s m.s. F Sig.

line 3 12.850 4.283 .821 .488 residual 56 292.000 5.214 total 59 304.850

χ²-test - line

LINE grade observed

N expected

N residual 1 A 4 5.0 -1.0 B 9 5.0 4.0 C 2 5.0 -3.0 total 15 2 A 4 5.0 -1.0 B 6 5.0 1.0 C 5 5.0 .0 total 15 3 A 7 5.0 2.0 B 4 5.0 -1.0 C 4 5.0 -1.0 total 15 4 A 8 5.0 3.0 B 4 5.0 -1.0 C 3 5.0 -2.0 total 15 Statistics of the test - line

LINE χ² df sig. 1 5.200 2 .074 2 .400 2 .819 3 1.200 2 .549 4 2.800 2 .247

95

χ²-test - grade

grade LINE observed

N expected

N residual A 1 4 5.8 -1.8 2 4 5.8 -1.8 3 7 5.8 1.3 4 8 5.8 2.3 total 23 B 1 9 5.8 3.3 2 6 5.8 .3 3 4 5.8 -1.8 4 4 5.8 -1.8 total 23 C 1 2 3.5 -1.5 2 5 3.5 1.5 3 4 3.5 .5 4 3 3.5 -.5 total 14 Statistics of the test – log grade

grade χ² df sig. A 2.217 3 .529 B 2.913 3 .405 C 1.429 3 .699

Appendix 10: Statistical analysis of the log eccentricity

Descriptive statistic of log eccentricity

LINE LOG N mean s.e. s.d. min max

1 b 15 .2552 3.056E-02 .1183 .08 .49

m 14 .2239 2.219E-02 8.304E-02 .10 .35

t 15 .2318 3.052E-02 .1182 .04 .43

2 b 14 .2512 3.696E-02 .1383 .06 .53

m 14 .2269 2.511E-02 9.394E-02 .07 .44

t 15 .2404 3.434E-02 .1330 .08 .52

3 b 15 .2192 2.076E-02 8.041E-02 .12 .40

m 15 .3037 3.905E-02 .1512 .06 .59

t 15 .2611 2.852E-02 .1104 .08 .42

4 b 15 .2021 3.382E-02 .1310 .02 .46

m 14 .2206 4.493E-02 .1681 .06 .65

t 16 .2995 4.495E-02 .1822 .09 .70

96

ANOVA max eccentricity. log

Eccentricity log Sums of square df mean of

squares F sig.

b between the groups 2.913E-02 3 9.710E-03 .689 .563 within the groups .755 55 1.410E-02 total .805 58 m between the groups 7.078E-02 3 2.359E-02 1.402 .253 within the groups .892 53 1.683E-02 total .963 56 t between the groups 4.090E-02 3 1.363E-03 .735 .535 within the groups 1.038 56 1.854E-02 total 1.079 59

Post Hoc test, Scheffé-procedure

s.e sig. 95%-conf. max eccent. log (I) LINE (J) LINE mean difference (I-J)

lower limit upper limit b 1 2 3.998E-03 4.412E-02 1.000 -.1233 .1313 3 3.604E-02 4.336E-02 .875 -8.8999E-02 .1611 4 5.312E-02 4.336E-02 .684 -7.1921E-02 .1782 2 1 -3.9985E-03 4.412E-02 1.000 -.1313 .1233 3 3.204E-02 4.412E-02 .912 -9.5211E-02 .1593 4 4.912E-02 4.412E-02 .744 -7.8133E-02 .1764 3 1 -3.6043E-02 4.336E-02 .875 -.1611 8.900E-02 2 -3.2045E-02 4.412E-02 .912 -.1593 9.521E-02 4 1.708E-02 4.336E-02 .984 -.1080 .1421 4 1 -5.3122E-02 4.336E-02 .684 -.1782 7.192E-02 2 -4.9123E-02 4.412E-02 .744 -.1764 7.813E-02 3 -1.7078E-02 4.336E-02 .984 -.1421 .1080 m 1 2 -2.9036E-03 4.903E-02 1.000 -.1445 .1387 3 -7.9709E-02 4.821E-02 .442 -.2189 5.950E-02 4 3.375E-03 4.903E-02 1.000 -.1382 .1450 2 1 2.904E-03 4.903E-02 1.000 -.1387 .1445 3 -7.6805E-02 4.821E-02 .475 -.2160 6.240E-02 4 6.279E-03 4.903E-02 .999 -.1353 .1479 3 1 7.971E-02 4.821E-02 .442 -5.9496E-02 .2189 2 7.681E-02 4.821E-02 .475 -6.2400E-02 .2160 4 8.308E-02 4.821E-02 .405 -5.6121E-02 .2223 4 1 -3.3749E-03 4.903E-02 1.000 -.1450 .1382 2 -6.2785E-03 4.903E-02 .999 -.1479 .1353 3 -8.3084E-02 4.821E-02 .405 -.2223 5.612E-02 t 1 2 -8.6054E-03 4.972E-02 .999 -.1519 .1347 3 -2.9304E-02 4.972E-02 .950 -.1726 .1140 4 -6.7688E-02 4.972E-02 .606 -.2110 7.563E-02 2 1 8.605E-03 4.972E-02 .999 -.1347 .1519 3 -2.0699E-02 4.972E-02 .982 -.1640 .1226 4 -5.9083E-02 4.972E-02 .704 -.2024 8.423E-02 3 1 2.930E-02 4.972E-02 .950 -.1140 .1726 2 2.070E-02 4.972E-02 .982 -.1226 .1640 4 -3.8384E-02 4.972E-02 .897 -.1817 .1049 4 1 6.769E-02 4.972E-02 .606 -7.5628E-02 .2110 2 5.908E-02 4.972E-02 .704 -8.4233E-02 .2024 3 3.838E-02 4.972E-02 .897 -.1049 .1817

97

ANALYSIS OF VARIANCE max eccent. log SOURCE of variation

df s.s m.s. F Sig.

LINE 3 1.689E-02 5.631E-03 .341 .795

LOG 2 2.059E-02 1.029E-03 .309 .537

LINE * LOG 6 .124 2.069E-02 1.254 .282

residual 164 2.706 1.650E-02

total 175 2.868

χ²-test – log_grade

Statistics of the test -

LOG χ² df sig. b 11.424 2 .003

m 9.579 2 .008

t .300 2 .861

χ²-test – log_grade Statistics of the test -

LINE χ² df sig. 1 2.909 2 .234

2 4.233 2 .120

3 .533 2 .766

4 1.273 2 .529

χ²-test - LINE Statistics of the test -

Grade_log χ² df sig. A 1.355 3 .716

B 1.087 3 .780

C 1.311 3 .726

98

Appendix 11: Statistical analysis of the log taper

Descriptive statistic of log taper [cm/m length]

LINE LOG N mean s.e. s.d. min max 1 b 15 1.6897 .2275 .8813 .21 3.87

m 14 .9014 8.646E-02 .3235 .55 1.75

t 15 1.3382 7.226E-02 .2798 .80 1.77

2 b 15 1.5582 .1404 .5439 .77 2.53

m 14 .8358 6.130E-02 .2294 .54 1.38

t 15 1.1732 5.056E-02 .1958 .70 1.43

3 b 15 1.2425 .1156 .4479 .75 2.11

m 15 .9314 6.211E-02 .2405 .64 1.44

t 15 1.1880 9.835E-02 .3809 .57 1.89

4 b 15 1.3698 .1601 .6199 .42 2.48

m 15 .7433 5.973E-02 .2313 .35 1.19

t 15 .9634 6.599E-02 .2556 .57 1.52

ANOVA log taper cm/m length

LINE Sums of square df mean of

squares F sig.

1 between the groups 4.508 2 2.254 6.932 .003

within the groups 13.330 41 .325

total 17.838 43



total 9.154 43

3 between the groups .828 2 .414 3.079 .057


total 6.478 44



total 10.074 44

99

Post Hoc test, Scheffé-procedure log taper cm/m length

LINE (I) log_pos (J) log_pos


lower limit upper limit 1 butt mid .7883* .2119 .003 .2501 1.3265 top .3515 .2082 .252 -.1773 .8804 mid butt -.7883* .2119 .003 -1.3265 -.2501 top -.4367 .2119 .133 -.9749 .1015 top butt -.3515 .2082 .252 -.8804 .1773 mid .4367 .2119 .133 -.1015 .9749 2 butt mid .7223* .1344 .000 .3810 1.0637 top .3849* .1321 .021 4.953E-02 .7204 mid butt -.7223* .1344 .000 -1.0637 -.3810 top -.3374 .1344 .053 -.6787 3.987E-03 top butt -.3849* .1321 .021 -.7204 -4.9528E-02 mid .3374 .1344 .053 -3.9870E-03 .6787 3 butt mid .3111 .1339 .079 -2.8714E-02 .6510 top 5.450E-02 .1339 .921 -.2853 .3943 mid butt -.3111 .1339 .079 -.6510 2.871E-02 top -.2566 .1339 .172 -.5965 8.321E-02 top butt -5.4500E-02 .1339 .921 -.3943 .2853 mid .2566 .1339 .172 -8.3214E-02 .5965 4 butt mid .6264* .1495 .001 .2469 1.0059 top .4063* .1495 .033 2.686E-02 .7858 mid butt -.6264* .1495 .001 -1.0059 -.2469 top -.2201 .1495 .348 -.5996 .1594 top butt -.4063* .1495 .033 -.7858 -2.6860E-02 mid .2201 .1495 .348 -.1594 .5996 * significantly different at p=0.05

Analysis of variance log taper [cm/m length]

SOURCE of variation

df s.s m.s. F Sig.

LINE 3 1.907 .636 3.362 .020

LOG_POSI 2 11.040 5.520 63.677 .000

LINE * LOG_POSI 6 1.203 .201 1.061 .388

residual 166 31.386 .233

total 177 45.597

100

χ²-test – line - grade

LINE grade observe

d N expected

N residual 1 grade B 32 22.0 10.0 grade C 12 22.0 -10.0 2 grade B 37 22.0 15.0 grade C 7 22.0 -15.0 3 grade B 39 22.5 16.5 grade C 6 22.5 -16.5 4 grade B 39 22.5 16.5 grade C 6 22.5 -16.5

Statistics of the test - grade_taper_num

LINE χ² df sig. 1 9.0961 1 .003 2 20.455 1 .000 3 24.200 1 .000 4 24.200 1 .000

χ²-test – log position - grade Log position grade observed N expected N residual b grade B 39 30.0 9.0 grade C 21 30.0 -9.0 total 60 m grade B 57 29.0 28.0 grade C 1 29.0 -28.0 total 58 t grade B 51 30.0 21.0 grade C 9 30.0 -21.0 total 60

Statistics of the test - log grade

LOG POS χ² df sig. B 5.400 1 .020 M 54.069 1 .000 T 29.400 1 .000

101

χ²-test – log grade - line LOG_GRAD line observed N expected N residual B 1 32 36.8 -6.0

2 37 36.8 -1.0

3 39 36.8 3.0

4 39 36.8 4.0

total 147

C 1 12 7.8 4,3

2 7 7.8 -.8

3 6 7.8 -1.8

4 6 7.8 -1.8

total 31

Statistics of the test - log grade -line

LOG POS χ² df sig. B .891 3 .828

C 3.194 3 .363

Appendix 12: Statistical analysis of the log ovality

Descriptive statistic of log ovality [/]

LINE LOG N mean s.e. s.d. min max 1 b 15 1.0673 1.148E-02 4.448E-02 1.00 1.16

m 14 1.0457 9.182E-03 3.435E-02 1.01 1.14

t 15 1.0513 8.215E-03 3.182E-02 1.01 1.14

2 b 15 1.0547 9.096E-03 3.523E-02 1.01 1.11

m 14 1.0500 7.263E-03 2.717E-02 1.00 1.09

t 15 1.0427 5.729E-03 2.219E-02 1.01 1.10

3 b 15 1.0487 9.605E-03 3.720E-02 .99 1.10

m 15 1.0747 1.207E-02 4.673E-02 1.02 1.20

t 15 1.0400 4.577E-03 1.773E-02 1.02 1.08

4 b 15 1.0453 8.387E-03 3.248E-02 .98 1.10

m 15 1.0447 6.239E-03 2.416E-02 1.02 1.10

t 15 1.0420 4.899E-03 1.897E-02 1.01 1.07

102

ANOVA log ovality [/]

Log position Sums of

square df mean of squares F sig.

b between the groups 4.227E-03 3 1.409E-03 .996 .401

within the groups 7.921E-02 56 1.415E-03

total 8.344E-02 59

m between the groups 8.898E-03 3 2.966E-03 2.515 .068


total 7.259E-02 57

t between the groups 1.133E-03 3 3.778E-04 .693 .560


total 3.164E-02 59

Post Hoc test, Scheffé-procedure log taper cm/m length

LINE (I) LINE (J) LINE mean difference (I-J) s.e sig. 95%-conf.

lower limit upper limit b 1 2 1.267E-02 1.373E-02 .837 -2.6918E-02 5.225E-02

3 1.867E-02 1.373E-02 .608 -2.0918E-02 5.825E-02

4 2.200E-02 1.373E-02 .470 -1.7585E-02 6.158E-02

2 1 -1.2667E-02 1.373E-02 .837 -5.2252E-02 2.692E-02

3 6.000E-03 1.373E-02 .979 -3.3585E-02 4.558E-02

4 9.333E-03 1.373E-02 .927 -3.0252E-02 4.892E-02

3 1 -1.8667E-02 1.373E-02 .608 -5.8252E-02 2.092E-02

2 -6.0000E-03 1.373E-02 .979 -4.5585E-02 3.358E-02

4 3.333E-03 1.373E-02 .996 -3.6252E-02 4.292E-02

4 1 -2.2000E-02 1.373E-02 .470 -6.1585E-02 1.758E-02

2 -9.3333E-03 1.373E-02 .927 -4.8918E-02 3.025E-02

3 -3.3333E-03 1.373E-02 .996 -4.2918E-02 3.625E-02

m 1 2 -4.2857E-03 1.298E-02 .991 -4.1743E-02 3.317E-02

3 -2.8952E-02 1.276E-02 .175 -6.5780E-02 7.876E-03

4 1.048E-03 1.276E-02 1.000 -3.5780E-02 3.788E-02

2 1 4.286E-03 1.298E-02 .991 -3.3172E-02 4.174E-02

3 -2.4667E-02 1.276E-02 .302 -6.1495E-02 1.216E-02

4 5.333E-03 1.276E-02 .981 -3.1495E-02 4.216E-02

103

3 1 2.895E-02 1.276E-02 .175 -7.8756E-03 6.578E-02

2 2.467E-02 1.276E-02 .302 -1.2161E-02 6.149E-02

4 3.000E-02 1.254E-02 .139 -6.1875E-03 6.619E-02

4 1 -1.0476E-03 1.276E-02 1.000 -3.7876E-02 3.578E-02

2 -5.3333E-03 1.276E-02 .981 -4.2161E-02 3.149E-02

3 -3.0000E-02 1.254E-02 .139 -6.6187E-02 6.187E-03

t 1 2 8.667E-03 8.523E-03 .793 -1.5899E-02 3.323E-02

3 1.133E-02 8.523E-03 .624 -1.3232E-02 3.590E-02

4 9.333E-03 8.523E-03 .754 -1.5232E-02 3.390E-02

2 1 -8.6667E-03 8.523E-03 .793 -3.3232E-02 1.590E-02

3 2.667E-03 8.523E-03 .992 -2.1899E-02 2.723E-02

4 6.667E-04 8.523E-03 1.000 -2.3899E-02 2.523E-02

3 1 -1.1333E-02 8.523E-03 .624 -3.5899E-02 1.323E-02

2 -2.6667E-03 8.523E-03 .992 -2.7232E-02 2.190E-02

4 -2.0000E-03 8.523E-03 .997 -2.6566E-02 2.257E-02

4 1 -9.3333E-03 8.523E-03 .754 -3.3899E-02 1.523E-02

2 -6.6667E-04 8.523E-03 1.000 -2.5232E-02 2.390E-02

3 2.000E-03 8.523E-03 .997 -2.2566E-02 2.657E-02

Analysis of variance log ovality [/]

SOURCE of variation

df s.s m.s. F sig.

LINE 3 3.496E-03 1.165E-03 1.115 .344

LOG_POSI 2 3.886E-03 1.943E-03 1.860 .159

LINE * LOG_POSI 6 1.066E-02 1.777E-03 1.701 .124

residual 166 .173 1.045E-03

total 177 .192

104

Appendix 13: Statistical analysis - proportion of juvenile wood

Descriptive statistics - % juv volume

LINE LOG N mean s.e. s.d. min max 1 b 15 21.2333 1.0784 4.1767 15.50 28.30

m 14 43.7857 2.4581 9.1973 28.10 61.00

t 14 60.1929 3.7106 13.8837 36.40 83.70

2 b 14 21.9786 1.0472 3.9182 16.90 29.30

m 12 46.8083 2.2859 7.9185 36.00 60.60

t 14 64.2286 2.3747 8.8855 53.60 81.00

3 b 15 19.8600 2.1485 8.3211 4.70 32.60

m 14 44.2000 2.4268 9.0801 19.10 58.60

t 15 64.5333 2.6190 10.1432 51.30 80.20

4 b 14 20.6143 1.6916 6.3294 8.80 31.50

m 13 47.3615 1.6071 5.7946 36.50 54.20

t 14 63.2071 1.6738 6.2628 53.80 74.20

ANOVA % juv volume

LINE Sums of square df mean of

squares F sig.


within the groups 3849.760 40 96.244

total 14973.423 42



total 14526.411 39



total 18487.699 43



total 14396.458 40

105

ANOVA - % juv volume

LOG Sums of square df mean of

squares F sig.

b between the groups 35.316 3 11.772 .329 .805


total 1969.306 57

m between the groups 130.293 3 43.431 .652 .586


total 3394.450 52

t between the groups 167.066 3 55.689 .538 .658


total 5649.567 56

Analysis of variance - % juv volume

SOURCE of variation df s.s m.s. F sig. LINE 3 159.146 53.049 .775 .510

LOG 2 51451.080 25725.540 375.744

.000

LINE * LOG 6 180.618 30.103 .440 .851

residual 156 10680.648 68.466

total 167 62590.793

106

Appendix 14: Statistical analysis – Log classification according to ENV 1927-1

χ²-test – log grade - line

LINE LOG observed N

expected N residual

1 b grade B 1 5.0 -4.0

grade C 12 5.0 7.0

grade D 2 5.0 -3.0

m grade B 2 4.7 -2.7

grade C 10 4.7 5.3

grade D 2 4.7 -2.7

t grade B -4.0 1 5.0

grade C 8 5.0 3.0

grade D 6 5.0 1.0

2 b grade B 1 7.5 -6.5

grade C 14 7.5 6.5

m grade B 3 4.7 -1.7

grade C 10 4.7 5.3

grade D 1 4.7 -3.7

t grade B 1 5.0 -4.0

grade C 12 5.0 7.0

grade D 2 5.0 -3.0

3 b grade B 7 7.5 -.5

grade C 8 7.5 .5

m grade B 3 5.0 -2.0

grade C 9 5.0 4.0

grade D 3 5.0 -2.0

t grade C 9 7.5 1.5

grade D 6 7.5 -1.5

4 b grade B 5 7.5 -2.5

grade C 10 7.5 2.5

m grade B 2 7.5 -5.5

grade C 13 7.5 5.5

t grade C 11 7.5 3.5

grade D 4 7.5 -3.5

107

Statistics for test: log grade

LINE χ² df sig. 1 25.273 2 .000

2 46.682 2 .000

3 12.133 2 .002

4 36.400 2 .000

Statistics for test: LINE

LOG GRADE χ² df sig. B 3.231 3 .357

C 1.873 3 .599

D 5.692 3 .128

Statistics for test: LOG GRADE

LOG χ² df sig. b 46.800 2 .000

m 40.276 2 .000

t 36.400 2 .000

108

χ²-test – downgrading

LINE Downgraded by observed N expected N residual

1 no down grade 4 6.3 -2.3

branchiness 16 6.3 9.7

branchiness, eccentricity 6 6.3 -.3

branchiness, taper 11 6.3 4.7

eccentricity 1 6.3 -5.3

eccentricity, taper 1 6.3 -5.3

taper 5 6.3 -1.3

2 no down grade 6 6.3 -.3


branchiness, eccentricity 3 6.3 -3.3

branchiness, taper 3 6.3 -3.3


taper 4 6.3 -2.3

branchiness, eccentricity, taper 1 6.3 -5.3

3 no down grade 10 5.0 5.0


branchiness, eccentricity 7 5.0 2.0

branchiness, taper 2 5.0 -3.0


taper 1 5.0 -4.0

branchiness, spiral grain 1 5.0 -4.0

eccentricity, spiral grain 1 5.0 -4.0

spiral grain 1 5.0 -4.0

4 no down grade 6 5.0 1.0


branchiness, eccentricity 6 5.0 1.0



taper 5 5.0 .0

branchiness, eccentricity, taper 1 5.0 -4.0

spiral grain 1 5.0 -4.0

spiral grain, taper 1 5.0 -4.0

109

Appendix 15: Statistical analysis – Stress grading

Statistics for test : difference in frequency of LINE C24 – C16 - reject

LINE χ² df sig. 1 5.239 2 .073 2 4.308 2 .116 3 5.097 2 .078 4 5.067 2 .079

Statistics for test : difference in frequency of C24-C16-reject LINE

grade χ² df sig. C16 1.448 3 .694 C24 3.746 3 .290

reject 10.000 3 .019

Appendix 16: Statistical analysis – Mechanical properties MOE, MOR

Descriptive statistics : MOEstat

LINE N mean s.e. s.d. min max 1 90 7807.5321 282.6766 2681.7058 4104.22 23809.71

2 92 8243.6739 207.9312 1994.4057 4184.00 15250.00

3 92 8266.6522 187.7372 1800.7115 4153.00 13533.00

4 90 7870.6751 252.1708 2392.3024 3852.00 17377.00

Descriptive statistics : MOR LINE N mean s.e. s.d. min max 1 91 32.1819 .9401 14.09 54.98 8.9675

2 92 34.5435 .8435 11.93 50.67 8.0905

3 94 32.6932 .9518 .00 57.91 9.2276

4 90 31.6126 .9298 12.61 61.04 8.8212

110

Analysis of variance - MOE [N/mm2]

SOURCE of variation df s.s m.s. F sig. LINE 12474782.918 3 4158260.973 .919 .432

LOG_POS 5382859.089 1 5382859.089 1.189 .276

WIND_DIR 54501513.106 3 18167171.035 4.014 .008

BAT_POS 31384323.406 2 15692161.703 3.467 .032

LINE * LOG_POS 99284688.489 3 33094896.163 7.312 .000

LINE * WIND_DIR 8333012.474 5 1666602.495 .368 .870

LOG_POS * WIND_DIR 4737361.368 1 4737361.368 1.047 .307

LINE * LOG_POS *

WIND_DIR

6270287.170 3 2090095.723 .462 .709

LINE * BAT_POS 23474306.302 3 7824768.767 1.729 .161

LOG_POS * BAT_POS 65487.296 1 65487.296 .014 .904

LINE * LOG_POS *

BAT_POS

28561653.140 2 14280826.570 3.155 .044

WIND_DIR * BAT_POS 6319715.281 1 6319715.281 1.396 .238

LINE * WIND_DIR *

BAT_POS

11770201.940 3 3923400.647 .867 .459

LOG_POS * WIND_DIR *

BAT_POS

5124873.221 1 5124873.221 1.132 .288

LINE * LOG_POS *

WIND_DIR * BAT_POS

10753197.598 1 10753197.598 2.376 .124

residual 1471069628.299 325 4526368.087

total 1822398534.199 363

111

Analysis of variance MOR [N/mm²]

SOURCE of variation df s.s m.s. F sig. LINE 112.585 3 37.528 .556 .644

LOG_POS 9.156 1 9.156 .136 .713

WIND_DIR 1203.911 3 401.304 5.950 .001

BAT_POS 670.221 2 335.111 4.968 .007

LINE * LOG_POS 246.858 3 82.286 1.220 .302

LINE * WIND_DIR 383.555 5 76.711 1.137 .340

LOG_POS * WIND_DIR 168.585 1 168.585 2.500 .115

LINE * LOG_POS *

WIND_DIR

102.483 3 34.161 .506 .678

LINE * BAT_POS 125.196 3 41.732 .619 .603

LOG_POS * BAT_POS 174.601 1 174.601 2.589 .109

LINE * LOG_POS *

BAT_POS

263.060 2 131.530 1.950 .144

WIND_DIR * BAT_POS .277 1 .277 .004 .949

LINE * WIND_DIR *

BAT_POS

78.624 3 26.208 .389 .761

LOG_POS * WIND_DIR *

BAT_POS

23.389 1 23.389 .347 .556

LINE * LOG_POS *

WIND_DIR * BAT_POS

3.075 1 3.075 .046 .831

residual 22055.320 327 67.447

total 27403.671 365

112

Appendix 17: Statistical analysis – Distortion –twist, bow, spring

Descriptive analysis “twist”

line log exposure inner outer

twist counts

twist average [mm]

twist st.dev [mm]

twist se [mm]

twist max [mm]

twist min [mm]

1 b 0 0 8 25.1 10.2 3.6 35 4 1 b l 1 15 11.9 9.4 2.4 29 2.5 1 b l 2 16 4.3 2.6 0.7 9.5 0 1 b w 1 14 14.8 11.4 3.0 45 1 1 b w 2 11 4.1 2.5 0.8 6 1 1 t l 1 13 16.6 9.6 2.7 33 1 1 t l 2 2 16.5 0.7 0.5 17 16 1 t w 1 11 18.0 6.0 1.8 28 8 1 t w 2 2 b 0 0 6 20.4 8.4 3.4 35 10 2 b l 1 14 9.8 8.3 2.2 33.5 2 2 b l 2 13 2.6 2.7 0.7 8.5 0.5 2 b w 1 14 16.5 11.0 3.0 34 1 2 b w 2 14 4.2 4.1 1.1 14 0.5 2 t l 1 15 14.9 8.3 2.1 32.5 4 2 t l 2 1 13.5 13.5 13.5 2 t w 1 12 18.6 6.5 1.9 30 11 2 t w 2 3 b 0 0 8 23.3 6.8 2.4 37 15 3 b l 1 15 5.5 3.9 1.0 14.5 1 3 b l 2 15 2.8 2.0 0.5 7 0.5 3 b w 1 15 11.3 10.2 2.6 34 3 3 b w 2 10 4.5 3.7 1.2 13 1 3 t l 1 13 14.7 5.1 1.4 20.5 5.5 3 t l 2 2 15.8 7.4 5.3 21 10.5 3 t w 1 13 14.2 4.4 1.2 20.5 4.5 3 t w 2 1 7.5 7.5 7.5 4 b 0 0 5 33.9 14.5 6.5 55.5 16 4 b l 1 14 11.3 8.2 2.2 32.5 1.5 4 b l 2 13 3.8 3.3 0.9 10.5 0.5 4 b w 1 14 17.8 13.4 3.6 41 1 4 b w 2 14 4.9 3.2 0.9 10.5 0.5 4 t l 1 13 17.6 9.2 2.5 33 0 4 t l 2 4 12.5 12.9 6.5 31 2.5 4 t w 1 9 17.7 8.2 2.7 28 6.5 4 t w 2 3 11.5 8.7 5.0 19 2

113

Descriptive analysis “bow”

line log exposure inner outer bow counts

bow average [mm]

bow stabw [mm]

bow se [mm]

bow max [mm]

bow min [mm]

1 b 0 0 8 3.35 1.80 0.63 5.5 0 1 b l 1 15 3.27 2.40 0.62 10.5 0 1 b l 2 16 4.81 5.90 1.47 21 1 1 b w 1 14 3.29 2.02 0.54 7.5 1.5 1 b w 2 11 6.30 9.93 2.99 33 0 1 t l 1 13 6.46 6.64 1.84 22 0 1 t l 2 2 13.50 0.71 0.50 14 13 1 t w 1 11 3.95 2.77 0.84 10 1.5 1 t w 2 2 b 0 0 6 3.50 0.84 0.34 5 3 2 b l 1 14 2.71 2.06 0.55 7 0 2 b l 2 13 1.85 1.63 0.45 5 0.5 2 b w 1 14 4.14 2.13 0.57 9 1 2 b w 2 14 2.00 1.22 0.33 5 0 2 t l 1 15 4.33 4.06 1.05 17 1 2 t l 2 1 1.00 1 1 2 t w 1 12 4.29 4.87 1.41 17.5 0.5 2 t w 2 3 b 0 0 8 3.19 2.43 0.86 8 0 3 b l 1 15 1.83 1.42 0.37 4.5 0 3 b l 2 15 2.73 2.84 0.73 9 0 3 b w 1 15 1.83 1.16 0.30 4 0 3 b w 2 10 1.70 1.55 0.49 6 0.5 3 t l 1 13 4.92 3.64 1.01 13 1 3 t l 2 2 10.00 1.41 1.00 11 9 3 t w 1 13 4.46 3.42 0.95 12 0.5 3 t w 2 1 7.00 7 7 4 b 0 0 5 4.00 3.24 1.45 8 1 4 b l 1 14 2.89 1.70 0.45 7 0.5 4 b l 2 13 2.65 2.24 0.62 8 0 4 b w 1 14 4.00 3.78 1.01 14 0.5 4 b w 2 14 2.79 2.38 0.64 10 1 4 t l 1 13 9.35 9.58 2.66 35 1 4 t l 2 4 5.25 3.30 1.65 10 3 4 t w 1 9 4.50 2.32 0.77 8 1 4 t w 2 3 4.67 2.08 1.20 7 3

114

line log exposure

inner outer

spring counts

spring average [mm]

spring stabw [mm]

spring se [mm]

spring max [mm]

spring min [mm]

1 b 0 0 8 3.9 2.2 0.8 8 1 1 b l 1 15 3.1 1.9 0.5 7 1 1 b l 2 16 2.7 3.0 0.7 12 0 1 b w 1 14 3.3 2.1 0.6 7 1 1 b w 2 11 2.1 0.8 0.3 4 1 1 t l 1 13 3.3 1.6 0.5 7 1 1 t l 2 2 3.5 0.7 0.5 4 3 1 t w 1 11 3.8 3.1 0.9 12 1 1 t w 2 2 b 0 0 6 4.1 2.5 1.0 8 1 2 b l 1 14 2.1 1.4 0.4 5 0.5 2 b l 2 13 1.8 0.9 0.2 3 0.5 2 b w 1 14 2.4 0.9 0.3 4 1 2 b w 2 14 2.0 1.9 0.5 7 0 2 t l 1 15 2.7 2.2 0.6 9 1 2 t l 2 1 2.5 2.5 2.5 2 t w 1 12 3.0 1.3 0.4 5.5 1.5 2 t w 2 3 b 0 0 8 4.5 3.5 1.2 11 2 3 b l 1 15 2.0 1.0 0.3 4 0.5 3 b l 2 15 2.0 1.2 0.3 5 0 3 b w 1 15 2.2 1.5 0.4 5 0.5 3 b w 2 10 1.5 0.8 0.3 3.5 1 3 t l 1 13 3.4 2.3 0.6 10 1 3 t l 2 2 6.0 5.7 4.0 10 2 3 t w 1 13 3.5 2.4 0.7 8.5 1 3 t w 2 1 2.0 2 2 4 b 0 0 5 3.5 0.6 0.3 4.5 3 4 b l 1 14 2.5 2.1 0.5 8 0 4 b l 2 13 1.9 0.8 0.2 3.5 1 4 b w 1 14 2.7 2.2 0.6 9 1 4 b w 2 14 1.5 0.7 0.2 3 0.5 4 t l 1 13 4.3 3.0 0.8 9.5 0.5 4 t l 2 4 1.5 0.6 0.3 2 1 4 t w 1 9 3.7 1.8 0.6 6.5 1.5 4 t w 2 3 4.3 1.3 0.7 5.5 3

115

Analysis of variance

twist [mm]

SOURCE of variation s.s df m.s. F sig. LINE 696.596 3 232.199 3.922 .009 LOG 1035.537 1 1035.537 17.491 .000 EXPOSURE 46.781 2 23.391 .395 .674 INNER_OU 492.939 1 492.939 8.326 .004 LINE * LOG 18.232 3 6.077 .103 .958 LINE * EXPOSURE 204.120 4 51.030 .862 .487 LOG * EXPOSURE 150.142 1 150.142 2.536 .112 LINE * LOG * EXPOSURE 80.830 3 26.943 .455 .714 LINE * INNER_OU 105.127 3 35.042 .592 .621 LOG * INNER_OU 127.245 1 127.245 2.149 .144 LINE * LOG * INNER_OU 27.919 3 9.306 .157 .925 EXPOSURE * INNER_OU 134.571 2 67.286 1.137 .322 LINE * EXPOSURE * INNER_OU

21.294 4 5.324 .090 .986

LOG * EXPOSURE * INNER_OU

.170 1 .170 .003 .957

LINE * LOG * EXPOSURE * INNER_OU

20.507 1 20.507 .346 .557

residual 19300.490 326 59.204 total 35662.595 363 bow [mm] SOURCE of variation s.s df m.s. F sig. LINE 82.396 3 27.465 1.803 .146 LOG 241.615 1 241.615 15.864 .000 EXPOSURE 27.570 2 13.785 .905 .406 INNER_OU 3.857 1 3.857 .253 .615 LINE * LOG 77.508 3 25.836 1.696 .168 LINE * EXPOSURE 54.864 4 13.716 .901 .464 LOG * EXPOSURE 26.230 1 26.230 1.722 .190 LINE * LOG * EXPOSURE 12.481 3 4.160 .273 .845 LINE * INNER_OU 125.180 3 41.727 2.740 .043 LOG * INNER_OU 13.332 1 13.332 .875 .350 LINE * LOG * INNER_OU 72.190 3 24.063 1.580 .194 EXPOSURE * INNER_OU 3.952 2 1.976 .130 .878 LINE * EXPOSURE * INNER_OU

54.244 4 13.561 .890 .470


4.620 1 4.620 .303 .582


15.075 1 15.075 .990 .321

residual 4980.368 327 15.230 total 11632.840 365

116

spring [mm] SOURCE of variation df s.s m.s. F sig. LINE 3 5.302 1.767 .474 .700 LOG 1 32.859 32.859 8.820 .003 EXPOSURE 1 .347 .347 .093 .760 INNER_OU 1 4.368 4.368 1.172 .280 LINE * LOG 3 7.594 2.531 .679 .565 LINE * EXPOSURE 3 16.403 5.468 1.468 .223 LOG * EXPOSURE 1 3.746E-

02 3.746E-02

.010 .920

LINE * LOG * EXPOSURE

3 13.382 4.461 1.197 .311

LINE * INNER_OU 3 6.025 2.008 .539 .656 LOG * INNER_OU 1 .924 .924 .248 .619 LINE * LOG * INNER_OU

3 1.895 .632 .170 .917

EXPOSURE * INNER_OU 1 1.445 1.445 .388 .534 LINE * EXPOSURE * INNER_OU

3 19.713 6.571 1.764 .154


1 .188 .188 .051 .822


1 18.852 18.852 5.060 .025

Fehler 325 1210.779 3.725 Gesamt 359 4194.750

117

Appendix 18: Statistical analysis – Batten density Descriptive statistics LINE LOG WIND BAT_POS N mean s.e. s.d. min max 1 B .00 6 456.2256 20.4494 50.0906 411.31 550.20 L 1.00 9 405.4302 14.3748 43.1243 342.18 474.70 2.00 9 421.0704 12.4577 37.3730 345.63 474.29 W 1.00 9 413.0841 17.6820 53.0459 369.35 530.14 2.00 6 391.7466 8.2219 20.1394 360.21 414.11 T 1.00 2 425.8028 2.5820 3.6515 423.22 428.38 2.00 2 444.3617 13.4840 19.0692 430.88 457.85 L 1.00 7 482.1906 30.0412 79.4814 382.36 600.25 2.00 2 495.4801 16.7975 23.7553 478.68 512.28 W 1.00 5 433.1723 15.2187 34.0301 387.08 464.84 2 B .00 6 396.3272 17.1895 42.1054 325.52 439.66 L 1.00 14 385.1406 14.0553 52.5901 291.30 483.70 2.00 12 373.2310 10.1134 35.0337 298.53 439.26 W 1.00 14 409.1312 16.0238 59.9555 339.52 544.04 2.00 13 382.1505 9.8319 35.4494 310.77 436.37 T 1.00 1 364.2954 . . 364.30 364.30 2.00 1 343.1189 . . 343.12 343.12 L 1.00 15 428.1921 11.3869 44.1014 347.05 510.54 2.00 2 427.4591 17.6056 24.8981 409.85 445.06 W 1.00 12 427.7618 11.5446 39.9917 350.59 510.90 3 B .00 8 421.4638 13.3558 37.7759 372.52 471.88 L 1.00 15 363.5846 11.2149 43.4350 295.20 439.82 2.00 13 388.7106 11.6150 41.8783 314.07 455.36 W 1.00 13 389.0029 15.4403 55.6709 284.76 517.06 2.00 12 376.8140 13.3028 46.0824 305.03 476.80 T L 1.00 14 404.3491 9.4331 35.2953 342.15 466.73 2.00 2 509.5062 58.5178 82.7567 450.99 568.02 W 1.00 13 399.9692 8.1853 29.5124 350.22 464.71 2.00 1 389.5979 . . 389.60 389.60 4 B .00 4 430.9347 24.8504 49.7008 379.74 495.76 L 1.00 9 395.0298 18.5186 55.5558 331.38 493.95 2.00 9 413.0553 19.0727 57.2181 324.59 514.23 W 1.00 10 418.5667 16.0582 50.7805 349.80 516.37 2.00 9 381.4871 13.5445 40.6334 319.95 427.99 T L 1.00 5 435.0472 40.3812 90.2952 365.02 572.92 2.00 2 387.2692 2.5753 3.6420 384.69 389.84 W 1.00 7 413.7069 19.3521 51.2010 346.56 484.27

118

Analysis of variance

DENSITY

SOURCE of variation s.s df m.s. F sig. LINE 28505.158 3 9501.719 4.292 .006 LOG 15168.044 2 7584.022 3.426 .034 WIND 24481.454 2 12240.727 5.529 .004 BAT_POS 521.512 1 521.512 .236 .628 LINE * LOG 17699.390 3 5899.797 2.665 .048 LINE * WIND 9898.397 4 2474.599 1.118 .349 LOG * WIND 16030.531 1 16030.531 7.241 .008 LINE * LOG * WIND 1481.654 3 493.885 .223 .880 LINE * BAT_POS 22518.717 3 7506.239 3.391 .019 LOG * BAT_POS 276.461 1 276.461 .125 .724 LINE * LOG * BAT_POS 13266.188 3 4422.063 1.997 .115 WIND * BAT_POS 16369.660 2 8184.830 3.697 .026 LINE * WIND * BAT_POS 2420.046 4 605.011 .273 .895 LOG * WIND * BAT_POS 3133.569 1 3133.569 1.415 .235 LINE * LOG * WIND * BAT_POS

.000 0 . . .

residual 566743.089 256 2213.840 total 781620.211 293

Appendix 19: Statistical analysis –Reaction wood

Descriptive statistics – compression wood ratio to batten surface

LOG_POS WIND LINE N mean s.e. s.d. min max butt centre 1.00 2 .8300 1.400E-02 1.980E-02 .82 .84 4.00 1 .6580 . . .66 .66 leewards 1.00 11 .6099 8.762E-02 .2906 .21 1.00 4.00 10 .4396 7.535E-02 .2383 .13 .76 windwards 1.00 9 .6146 .1032 .3097 .20 1.00 4.00 10 .2789 6.930E-02 .2191 .04 .60 top leewards 1.00 6 .8352 6.333E-02 .1551 .58 1.00 4.00 5 .7152 .1240 .2772 .34 1.00 windwards 1.00 6 .5305 .1375 .3368 .05 1.00 4.00 5 .3976 4.244E-02 9.491E-02 .23 .46

119

ANOVA - CW_MEAN

LOG_POS WIND

Sums of

square df

mean of

squares F sig.

butt centre between the groups 1.972E-02 1 1.972E-02 50.313 .089 within the groups 3.920E-04 1 3.920E-04 total 2.011E-02 2 leewards between the groups .152 1 .152 2.130 .161 within the groups 1.355 19 7.134E-02 total 1.507 20 windwards between the groups .534 1 .534 7.565 .014 within the groups 1.199 17 7.055E-02 total 1.733 18 top leewards between the groups 3.925E-02 1 3.925E-02 .826 .387 within the groups .428 9 4.753E-02 total .467 10 windwards between the groups 4.817E-02 1 4.817E-02 .719 .418 within the groups .603 9 6.701E-02 total .651 10

Analysis of variance Compression wood ratio

SOURCE of variation df s.s m.s. F sig. LINE .209 1 .209 3.179 .080 LOG_POS .253 1 .253 3.851 .055 WIND .701 3 .234 3.560 .020 LINE * LOG_POS 5.642E-02 1 5.642E-02 .860 .358 LINE * WIND 3.193E-02 2 1.597E-02 .243 .785 LOG_POS * WIND

.191 1 .191 2.919 .093

LINE * LOG_POS * WIND

2.046E-02 1 2.046E-02 .312 .579

residual 3.673 56 6.560E-02 total 5.524 66 a R-Quadrat = .335 (korrigiertes R-Quadrat = .216)

the influence of the site factors wind exposure and slope

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