forestry & society silviculture hort/rgsc 302 j.g. mexal fall 2005
TRANSCRIPT
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Forestry & Society
Silviculture
HORT/RGSC 302
J.G. Mexal
Fall 2005
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Forestry & Society
Silviculture/Outline
• Allowable Cut Effect• Site Index (SI)• Regeneration• Stocking• Thinning
• Fertilization• Competition Control• Pruning• Wood Quality• Agroforestry
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Forestry & Society
Allowable cut/ Kimmins
Allowable Cut = 1/6/decade
Function of: site index, silviculture, tree improvement, rotation age
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Forestry & Society
Site Index• Site Index is a measure of site productivity
and refers to the height of dominant and codominant trees in even-aged stands at a particular index age, usually 25, 50, or 100 years.
• Site Index is a function of environmental factors (soil depth, rainfall, tree species, growing season).
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Forestry & Society
Silviculture - Site Quality/ Spurr 1964
Sandy loam Clay loam Heavy Clay
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Forestry & Society
Silviculture - Site Index/ Spurr 1964
Height (ft)Pine - Finland
SI100
SI50
SI25Cladina type
Calluna typeVaccinium typeMyrtillus type
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Forestry & Society
Site Index (SI50)/Wenger 1984
0
20
40
60
80
100
120
140
160
180
0 20 40 60 80 100
SI 60
SI 80
SI 100
SI 120
Years
Height (ft)
Loblolly pine
0
20
40
60
80
100
120
140
160
180
0 20 40 60 80 100
SI 60
SI 80
SI 100
SI 120
Douglas-fir in WA
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Forestry & Society
Site Index (SI50)/Wenger 1984
0
20
40
60
80
100
120
140
160
180
0 20 40 60 80 100
SI 40SI 60SI 80SI 100SI 40SI 80SI 120
Years
Height (ft)
Ponderosa pine in CA
SI50SI100
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Forestry & Society
Silviculture/Site Quality/ Schultz 1997
SouthwideFlatwoods (heavy clay)
Plantation age (yrs)
Southern Pines
SI25
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Forestry & SocietySilviculture/DBH vs Hgt & Biomass -Shepherd1986
0
40
80
120
160
200
240
280
10 12 14 16 18 20
Biomass (kg)DBH
Biomass (kg)
Height (m)
24
20
16
12
8
4
DBH (cm)
Pinus radiata- NZ-16 yr plantation
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50 60 70 80
Site Index
Dry Weight (ton/ac) Age
Needles
Branches
Total
Forestry & Society
Silviculture/Site Quality vs Biomass Distribution/Tree Physiol. 3:42:1987
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Forestry & Society
Silviculture/Outline
• Allowable Cut Effect• Site Index (SI)• Regeneration• Stocking• Thinning
• Fertilization• Competition Control• Pruning• Wood Quality• Agroforestry
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Forestry & Society
Silviculture/Natural Regeneration
Time
2,000,000
200,000
20,000
2,000
200
No./ha Volume Growth (m3/ha/yr)
5
10
15
20
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Forestry & Society
Silviculture/Artificial Regeneration
Time
2,000,000
200,000
20,000
2,000
200
No./ha Volume Growth (m3/ha/yr)
5
10
15
20
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Forestry & Society
Silviculture/Clearcut does not eliminate species (necessarily)/ Bettis, 9th So.Silv.Res.Conf.
0
300
600
900
1200
1500
1800Clearcut (leave <6' tallSilvi-cut (cut<6'tall)Herb or Fell & Burn
Planted 600 tpa
Stems/acre
Pine
Oak Ridge, TN
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Forestry & Society
Silviculture/Clearcut does not eliminate species (necessarily)/J.For. 24(1)37-44:2000
0500
1000150020002500300035004000
Clearcut & PlantFell,Burn & PlantSeed Tree
Stems/acre Coastal Plain, AL
*
*
Planted 300 tpa
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Forestry & Society
Silviculture/Change is Inevitable /Mich. Forest Ecology 1964
0
50
100
150
200
250
300
350
1930 1935 1940 1945 1950 1955 1960 1965
Sugar maple Red maple Red oakPaper birch Yellow birch Aspen
Trees/acre B.A. ft2/ac
0
10
20
30
40
50
60
70
1930 1935 1940 1945 1950 1955 1960 1965
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Forestry & Society
Silviculture/ Change is Inevitable Forest Ecology, 1964
02468
101214161820
1922 1924 1927 1932 1938 1945 1948
100 largestOthersDied-1948Died-1938Died-1927Died-1924
Year
DBH (in)
D D D D
Pseudotsuga menziesii - NZ
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Forestry & Society
Old Orchard Plantation (NC)/Pinus strobus
March1899 April 1999thinned
J. For. 98:18-23:2000
0
50
100
150
200
250
300
0 20 40 60 80 100 120
SI 75SI 56SI 71-thinned
SI 75SI 56
SI 71 thinned
BA (ft2/ac)
Years
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Forestry & Society
Old Orchard Plantation (NC)/Pinus strobus
Plot Density (trees/ac)
Height (ft)
DBH (in)
Gross Vol. (ft3/ac)
SI50 56 unthinned
280 107 12.9 20,217 (86%)1
SI50 75 unthinned
168 122 17.2 28,070 (80%)
SI50 71 thinned
88 124 20.9 24,514 (73%)
1 % = % standing volume (gross volume less removals and mortality)
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Forestry & SocietyConversion from Even-Aged to Uneven-Aged/
GTR SO 118, 1996
Southern Pine - 50 yrs old
Removed 2,114 b.f.Reproduction
DBH (in) DBH (in)
Before
After
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Forestry & SocietyConversion from Even-Aged to Uneven-Aged/
GTR SO 118, 1996
Southern Pine - 50 yrs old
ReproductionReproduction
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Forestry & Society
Silviculture/Changing Harvest Strategies/
USFS SO-112, 1994
Year Uneven Aged Manaement
(ac/yr)
Even Aged Management
(ac/yr) 1967-1988 0 12,800
1988-1992 2,876 4,890
Ouachita Nat’l For. Harvested AcresClearcut
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Forestry & Society
Silviculture/Changing NFS Harvest Strategies/ Policy Studies J. 23:274:1995
0%
20%
40%
60%
80%
100%
1984 1985 1986 1987 1988 1989 1990 1991
Selection cutEven-aged cutClearcut
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Forestry & Society
Silviculture/Harvest Marking Costs / USFS SO-112, 1994
0
1
2
3
4
5
Commercialthinning
Single-treeselection
Shelterwood Clearcut
SuppliesLabor
$/100 ft3
Southern Pines/ Ouachita N.F. AR
Harvesting Method
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Forestry & Society
Silviculture/Harvest Costs / SJAF 18:168-174:
0
5
10
15
20
25
30
35
Single-treeselection
Shelterwood Clearcut
$/CCF
Southern Pines/ Ouachita N.F. AR
Harvesting Method
Cable SkidderGrapple Skidder
Felling
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Forestry & Society
Silviculture/Thinning Method vs Damage/WJAF 15:27-33:2000
0
2
4
6
8
10
12
50-55 tpa 110-120 tpa 110-120 patch
SkylineTractorCut-to-LengthHelicopter
Residual Stand (tpa)
Scar Area (ft2/ac)
Pseudotsuga menziesii- OR
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Forestry & Society
Silviculture/Outline
• Allowable Cut Effect• Site Index (SI)• Regeneration• Stocking• Thinning
• Fertilization• Competition Control• Pruning• Wood Quality• Agroforestry
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Forestry & Society
Silviculture/ Stocking affects Growth/ Shepherd 1986
0
10
20
30
40
50
0 500 1000 1500 2000 2500 3000
Eucalyptus grandis-4 yr
Pinus radiata-15 yr
Basal Area
DBH
Stocking (trees/ha)
DBH (cm) or BA (m2/ha)
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Forestry & Society
Silviculture/ Stocking affects Growth/ USDA Hndbk 713, 1997
0
5
10
15
20
25
0 1000 2000 3000 4000 5000 6000 7000
10 yrs14 yrs20 yrs
Trees/ha
DBH (cm)
Pinus taeda
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Forestry & SocietySilviculture/ Stocking affects Biomass Distribution/ Shepherd 1986
0%
20%
40%
60%
80%
100%
550 1070 2200 4330
Stocking (trees/ha)
Twigs + needlesBranchesStembar,Stemwood
92127
171190
(tons/ha)
Pinus resinosa- (27 yrs)
k
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Forestry & SocietySilviculture/ Stocking affects Biomass Distribution/ Shepherd 1986
Pinus resinosa- (27 yrs)
2.4m1.7m 1.2m 1.0m
Trees/ha
550 1070 2220 4330
crowndiameter
170 kg 120 kg 80 kg 40 kgBiomass
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Forestry & SocietySilviculture/ Stocking affects Volume Growth/
Shepherd 1986
0
5
10
15
20
25
30
35
0 10 20 30 40 50 60
15-17 yrs20-23 yrs27-31 yrs
Basal Area (m2/ha)
Volume growth (m3/ha) Pinus radiata- NZ
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Forestry & Society
Silviculture/Outline
• Allowable Cut Effect• Site Index (SI)• Regeneration• Stocking• Thinning
• Fertilization• Competition Control• Pruning• Wood Quality• Agroforestry
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Forestry & Society
Silviculture/Weed Control & Fertilization/ New For. 14:233:’97
y = 19.29 - 0.006x
R2 = 0.82
y = 47.09 - 0.015x
R2 = 0.78
0
10
20
30
40
50
0 500 1000 1500 2000 2500
FertilizedNot Fertilized
Herbaceous Cover (kg/ha)
Tree Volume (m3)
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Forestry & SocietySilviculture/Fertilization/ Shepherd 1986
0
1
2
3
4
Nil N (200 kg/ha) P (125 kg/ha) N + P
Fertilizer Regime
Height (m)
Pinus radiata - 3.5 yr)
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Ponderosa pine growth after 31 yrs vs competition/PSW-RP-231, ‘97
Survival = 99%DBH = 7.8 cmCover = 24,000 ft2/acPine cover = 100%
Survival = 98%DBH = 6.11 cmCover = 24,200 ft2/acPine cover = 50%
Survival = 98%DBH = 4.56 cmCover = 33,500 ft2/acPine cover = 33%
Survival = 81%DBH =2.148 cmCover = 33,150 ft2/acPine cover = 12%
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Forestry & SocietySilviculture/Fertilization + Weed Control/
Shepherd 1986
0
1
2
3
4
Nil Herbicide N + P Herb. + NP
Fertilizer Regime
Height (m)
Pinus radiata - NZ(4 yr)
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Forestry & SocietySilviculture/Fertilization + Weed Control/
Shepherd 1986
0
1
2
3Nil P
N+P N+P+K
Height (m)Pinus radiata - NZ(4 yr)
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Forestry & SocietySilviculture/Fertilization vs Growth/ Schultz 1997
0
5
10
15
20
25
30
Control Cultivation Cultivation +NPK
Cultivation+2NPK
Cultivation +4NPK
Loblolly
Longleaf
Slash
DBH (cm)Southern Pines
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Forestry & SocietySilviculture/ Stocking affects Volume Growth/
PNW-RP-513, 1999
0
300
600
900
1200
1500
24201714119
Treatment (initiated @ Age 9)
Volume (cu ft)
Douglas-fir-ORPlantation age
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Forestry & Society
Silviculture/Outline
• Allowable Cut Effect• Site Index (SI)• Regeneration• Stocking• Thinning
• Fertilization• Competition Control• Pruning• Wood Quality• Agroforestry
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Forestry & Society
Piece Size vs Value/Barbour, USFS-1999
0
10
20
30
40
50
0 2 4 6 8 10 12 14 16
8 foot log small end diameter (in)
Value/log ($)
veneer
lumber
pulpfuel
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Forestry & Society
Product vs Value
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0
3
6
9
12
15
18Initial 3 yr Growth
Forestry & Society
Silviculture/Pruning vs Diameter Growth/ Shepherd 1986
DBH (cm)
Yr-6 Yr-7 Yr-8 Yr-9Pruning Year
C C C CP P P P
52%
40%32%
26%
% pruned
Pinus radiata/NZ
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Forestry & Society
Silviculture/Pruning vs Clear wood/ Shepherd 1986
Pinus radiata/NZ7
6
5
4
3
2
1
1st lift
2nd lift
3rd lift
010 1020 20Diameter from center (cm)
Height (m)
Clearwood zone
Knotty core
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Forestry & Society
Silviculture/Management Affects Runoff /Erosion in Alabama Grace, JSoilWaterConsv 59:160:04
y = 6.2019Ln(x) - 15.129
R2 = 0.60
y = 3.3811Ln(x) - 10.205
R2 = 0.47
0
5
10
15
20
25
0 50 100 150 200 250 300
Control- runoff
Harvested-runoff
Rainfall event (mm)
Runoff (mm)
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Forestry & Society
Silviculture/Management Affects Runoff /Erosion in Alabama Grace, JSoilWaterConsv 59:160:04
0
0.04
0.08
0.12
0.16
0.2
0 50 100 150 200 250 300
Control-erosion
Harvested-erosion
Rainfall event (mm)
Erosion (t/ha)
ErosionControl = 0.07 t/ha/yr (20 mo) Clearcut = 0.8 t/ha/yr (20 mo)
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Forestry & Society
Silviculture/Outline
• Allowable Cut Effect• Site Index (SI)• Regeneration• Stocking• Thinning
• Fertilization• Competition Control• Pruning• Wood Quality• Agroforestry
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Forestry & Society
Agroforestry- Windbreaks/ Spurr 1964
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H/R 302 Forestry & SocietyAgroforestry Systems/ Clason & Robinson JF98:2000
Yr 20520 tpa
BA = 209 ft2
Ht = 58’DBH = 8.6 “
250 tpa27 cords/ac
Yr 25100 tpa
3 cords +1,600 BF/ac
Yr 3050 tpa1 cords +2,100 BF/ac
Yr 350 tpa1 cords +3,100 BF/ac
Yr 2550 tpa3 cords +2,000 BF/
Yr 3050 tpa0 cords +3,000 BF/
Yr 350 tpa0 cords +4,000 BF/
100 tpa33 cords/ac
Silvopasture
Silviculture
+ 1 - 4 tons forage/ac/yr
Establishment costs of pasture = $260-$470/ac @ yr 20Annual fertilizer application ($60/ac/yr) to pasture also increases wood yield
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0
3
6
9
12
15
18
1986 1988 1990 1992 1994 1996 1998
Control-grazedVelpar-fencedControl-fencedSeeded-grazed
H/R 302 Forestry & SocietyAgroforestry Systems/PSW-RP-242, 1999
Year
Height (ft) Ponderosa pine, CA
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Forestry & Society
Silviculture/Foliage Biomass vs Height/ Shepherd 1986
0
10
20
30
40
50
60
0 5 10 15 20 25 30
Height (m)
Needle/total biomass (%)
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Forestry & Society
Silviculture/Foliage Biomass vs Age/ Shepherd 1986
0
5
10
15
20
25
30
0 10 20 30 40 50 60
Pinus radiataPinus sylvestrisEucalyptus grandisCryptomeria japonica
Plantation Age (yrs)
Foliage Biomass (t/ha)
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Forestry & Society
Silviculture/Review Questions
• Define: allowable cut, site index, BA, rotation age, false ring, clear cut
• Describe different silvicultural practices (e.g. fertilization, weed control, etc), their uses and forest response.
• What is the -3/2 rule? How is it used in forestry?• Describe the process of conversion from even-
aged to uneven-aged management to a forest. Why would you want to do that?
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Forestry & Society
Silviculture/Review Questions
• Discuss the changes in species composition, stocking and size over time in a forest ecosystem.
• Discuss the effects of clear-cutting and planting only one species on tree species diversity.
• Discuss the advantages and disadvantages of low stocking (300 trees/acre) compared to high sticking (1,000 trees/acre).
• What is agroforestry and why is it practiced?• Compare natural vs artificial regeneration.
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Forestry & Society
Silviculture/Review Questions
• What is the average DBH of sugar maple in a forest where there are 200 tpa with a BA of 60 ft2/ac
• Discuss the costs both economic and biologically of different harvest strategies.