The Value of Trees

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The Value of Trees

• Arboriculture
• J.G. Mexal
• Spring 2001

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Roots growing between concrete slabs
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Arboriculture The Value of Trees/Pirone 2000

• Supply Oxygen
• Sequester Carbon Dioxide
• Reduce Noise Pollution
• Trap Particulates
• Alter Microclimate
• Improve Aesthetics
• Enhance Outdoor Urban Spaces
• Alter the Character of a Community
• Provide products

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How a Tree Grows

• Arboriculture
• J.G. Mexal
• Spring 2001

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ArboricultureHow a Tree Grows
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ArboricultureHow a Tree Grows-Terms

• Trunk or bole
• Crown
• Terminal bud (scar)
• Apical dominance- terminal bud
• Apical control - crowns
• excurrent- strong apical control
• conifers, sweetgum, holly,
• decurrent- weak apical control
• most deciduous trees

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Woody Stem Structure
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ArboricultureHow a Tree Grows-Terms
Excurrent
Decurrent
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ArboricultureHow a Tree Grows-Terms

• Earlywood
• Latewood
• Sapwood
• Heartwood
• Tracheid-(conifers)
• Vessel- (hardwoods)

• Cambium
• Xylem
• Phloem
• Bark
• Periderm
• Cork cambium

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Forestry SocietyXylem production- earlywood vs
latewood
Phloem
1,2 Developing xylem cells
3,4 Latewood cells
5 Earlywood cells
L Preceeding year
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Forestry SocietyHow a Tree Grows/Diffuse vs
Ring Porus
Silver Maple
White Oak
50X
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Forestry SocietyHow a Tree Grows-Idealized
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Tree Growth

• Maximum diameter growth occurs at the base of the
  live crown.
• As the tree grows, the crown tends to rise with
  increased shading.
• Basal pruning raises the crown and raises the
  point of maximum diameter growth.

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Tree Growth

• Maximum diameter growth occurs at the base of the
  live crown.
• As the tree grows, taper decreases, creating a
  more cylindrical bole.
• Often there may be some flare at the butt of the
  bole (not illustrated).

Year 3
Year 2
Year 1
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ArboricultureHow a Tree Grows-shoots
Shoot elongation (cm)
Whorl number
Branch type
Physiol. Of Woody Plants p428
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Forestry Society Shoot Growth in Eastern White
Pine
Terminal growth 44 cm
Lateral branch 26 cm
2o lateral 12 cm
Lateral branch 19 cm
Lateral branch 14 cm
2o lateral 10 cm
3o lateral 6 cm
2o lateral 10 cm
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ArboricultureHow a Tree Grows-Terms

• Radical
• Taproot
• Lateral root
• 1o
• 2o
• Mycorrhiza(s) e
• ectomycorrhiza
• endomycorrhiza
• Root hair

• Sinker root
• Mother root
• Actinorhiza
• Russian olive
• Alder
• Nitrogen fixer
• Legumes

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ArboricultureHow a Tree Grows-roots (7 wks)
Robinia pseudoacacia
Pinus taeda
(cm)
(cm2)
(cm2)
(cm2)
(cm2)
(cm)
Physiol. Of Woody Plants p 27
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ArboricultureHow a Tree Grows-roots
Percent
Pinus taeda
? Growing tips
Physiol. Of Woody Plants p 28
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Quercus rubra (red oak) wound
10 Bark characteristics 9 Normal growth
resumes 8 Excessive growth to recover 7
Tree harvested in spring 6 Recovery takes 5
years 5 Walling-off the injury 4
Buckshot wound 3 Declining growth
(competition?) 2 Rapid early growth 1
Pith
http//www.chesco.com/treeman/SHIGO/AUTO.html
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Piñon response to transplanting
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ArboricultureHow a Tree Grows

• Dormancy-lack of visable growth
• Ecodormancy- environmental stress induced
• Endodormancy- requires chilling
• Paradormancy- regulated by other buds
• Cold-hardiness
• Ability to survive freezing temperatures
• Function of tissue, season, growth stage

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Dormancy Cold-hardinessDormancy Cycle/
Fujigama and Nee 1987
Degree Growth Stage Model
Growth
90
180
0
270
360
Dormancy
Cold Hardiness (oC)
0
-5
-10
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Dormancy Cold-hardinessDormancy Cycle/
Fuchigama and Nee 1987
Degree Growth Stage Model
Eco-
Eco-
Endodormancy
Growth
90
180
0
270
360
Dormancy
Cold Hardiness (oC)
0
-5
-10
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Dormancy Cold-hardinessDormancy Cycle/Zones of
Manipulation
Degree Growth Stage Model
Growth
90
180
0
270
360
Dormancy
Cold Hardiness (oC)
0
-5
-10
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Dormancy Cold-hardiness Dormancy Cycle
intensity varies
Photoperiod
Photoperiod
36o N latitude
45o N latitude
Relative Dormancy
30o N latitude
20o N latitude
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Dormancy Cold-hardinessDormancy Cycle Role of
Water-Grape/ Fennnel Line 2001
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Dormancy Cold-hardiness Factors Affecting
Acclimation-Tissue

• Tolerant
• Pinus pinea
• Shoots -40oC
• Roots -10oC

• Intolerant
• Eucalyptus camaldulensis
• Shoots -10oC
• Roots -3oC

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Dormancy Cold-hardiness Factors Affecting
Acclimation-Size

• Spring
• Buds -3o
• Cambium -4o
• Roots -4o
• Seedling -3o
• Germinant -2o

• Winter
• Buds -25o
• Cambium -50o
• Roots -10o
• Seedling -30o

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Dormancy Cold-hardiness Winter Injury
Increases with Severe Water Stress- Leucaena
leucocephala/ Mexal unpubl.
Dieback ( of maximum)
Distance from runoff water (m)
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Dormancy Cold-hardiness Cold - Hardiness of
Apple Blooms
Growth Units
Chilling Units
20
1.0
0.5
15
10
0
-0.5
5
-1.0
0
0
15
10
5
20
25
30
Temperature (oC)
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Dormancy Cold-hardiness Cold - Hardiness of
Apple Blooms
LT50 (oC)
Tight Cluster
12mm Green
Full Bloom
Full Pink
Green Tip
Dormant
Photos by
Silver Tip
Growing Degree Hours (oC)