Lecture 11FORE 3218

Forest Mensuration IIForest Mensuration II

Lectures 11Lectures 11

Stocking and Stand DensityStocking and Stand Density

Avery and Burkhart,Avery and Burkhart,

Chapter 15Chapter 15

Lecture 11FORE 3218

Definitions Definitions

Stand Density Stand Density –is a quantitatively term describing –is a quantitatively term describing the degree of stem crowding within a stocked areathe degree of stem crowding within a stocked area– Absolute or relative Absolute or relative

StockingStocking –refers to the adequacy of a given stand –refers to the adequacy of a given stand density to meet some density to meet some management objectivemanagement objective– Understocked, fully stocked, or overstockedUnderstocked, fully stocked, or overstocked

Stand density and stocking are often applied Stand density and stocking are often applied interchangeably interchangeably

A stand that is “overstocked” for one management objective could be “understocked” for another

Lecture 11FORE 3218

Measures of Stand DensityMeasures of Stand Density

Stand density – measures how thickly trees grow Stand density – measures how thickly trees grow in a standin a stand– Stems per unit areaStems per unit area

– Basal areaBasal area

– VolumeVolume

– IndicesIndices

Lecture 11FORE 3218

Measures of Stand DensityMeasures of Stand Density

Stems per unit areaStems per unit area Basal areaBasal area Relative stand densityRelative stand density Crown competition factorCrown competition factor

Black spruce

0

2000

4000

6000

8000

10000

0 20 40 60 80 100

Stand age (years)

Ste

ms

per

ha

Subject stand

Fully stocked

Lecture 11FORE 3218

Stems per unit areaStems per unit area Basal areaBasal area Relative stand densityRelative stand density Crown competition factorCrown competition factor Black spruce

0

10

20

30

40

0 20 40 60 80 100

Stand age (years)

Ba

sa

l a

rea

(m

2 /ha

)

Fully stocked

Measures of Stand Density (Measures of Stand Density (cont.cont.))

N

iibBA

1

2)2

( ii

db

Subject stand

Lecture 11FORE 3218

Ontario’s Jack Pine DMD (Archibald & Bowling. 1995. OMNR NEST TN-005)

Zone of Imm

inent Com

petition Mortality

Zone of crown closure

RSD=1

=0.55

=0.15

Measures of Stand Density (Measures of Stand Density (cont.cont.))

Stems per unit areaStems per unit area Basal areaBasal area Relative stand densityRelative stand density Crown competition factorCrown competition factor

RSD =Density of the subject stand

Maximum density attainable with the same as the subject standV

3/2 law of self thinning

aNV log2/3log

Lecture 11FORE 3218

Measures of Stand Density (Measures of Stand Density (cont.cont.))

Stems per unit areaStems per unit area Basal areaBasal area Relative stand densityRelative stand density Crown competition factorCrown competition factor

– reflects the area available to the average tree in a stand in relation to the maximum area it could use if it were open-grown

2)2

(CW

MCA

DBHbb 10

100(%) 1 a

MCA

CCF

N

ii

Lecture 11FORE 3218

Measures of Point DensityMeasures of Point Density

n

jj

ii aA

CI1

1

Quantify the competition level at a Quantify the competition level at a given point or a tree in a standgiven point or a tree in a stand

rcompetitioth theof overlap of area

rscompetitio ofnumber

eesubject trfor circlen competitio of area

eesubjext trfor index n competitio

ja

n

iA

iCI

j

i

i

Area overlap indexArea overlap index

Lecture 11FORE 3218

Measures of Point DensityMeasures of Point Density

n

j ij

iji DIST

DDCI

1

/

Distance-weighted size ratiosDistance-weighted size ratios

competitorth and treeebetween th distanceDIST

eesubject trth theofdbh

competitorth theofdbh

scompetitor ofnumber

eesubjext trfor index n competitio

ji

iD

jD

n

iCI

ij

i

j

i

Lecture 11FORE 3218

StockingStocking

A ratio of comparison of A ratio of comparison of the density of a subject the density of a subject stand to that of a “ideal” stand to that of a “ideal” or reference stand or reference stand – VolumeVolume– Basal areaBasal area

Lecture 11FORE 3218

Measures of StockingMeasures of Stocking

What should constitute full stocking of a What should constitute full stocking of a particular species on a given site?particular species on a given site? – NormalNormal or fully stocked stand: or fully stocked stand: in such a hypothetical in such a hypothetical

stand, tree crowns are fitted together so that no stand, tree crowns are fitted together so that no sunlight is wasted and each crown is matched with a sunlight is wasted and each crown is matched with a root system that fully utilizes the soilroot system that fully utilizes the soil

Normal stands are “Normal stands are “average bestaverage best” -- closed ” -- closed canopy stands canopy stands

Lecture 11FORE 3218

MeasuresMeasures– Mature standsMature stands– Stands at Stands at

regeneration stageregeneration stage

Stocking (Stocking (cont.cont.))

Lecture 11FORE 3218

Stocking GuidesStocking Guides

Depicts the relationship between basal area, Depicts the relationship between basal area, trees per ha, and quadratic diameter at breast-trees per ha, and quadratic diameter at breast-heightheight

Trees per ha

Bas

al a

rea

per

ha

Mean DBH (cm)

A

B

10

1520

25

30