Tree Biology
Growth I
Ancient Forest of Eastern North America
• Thuja occidentalis along
Niagara Escarpment in
Ontario
• Oldest 1653 years old;
many > 900 years
www.globalforestscience.org
Cortland’s Landmark
Street Trees
Hyde’s Diner
Eastern Cottonwood
Height : 105 feet
Canopy Width: 54 feet
Trunk Circumference: 250 inches (DBH~ 6 ft)
Replacement Value: $8,200
Annual Environmental Services: $215
European Horse Chestnut 70 ft and 154 inches
Silver Maple 60 feet and 218 inches
Red Oak 79 feet and 216 inches
In 1978, General Sherman dropped
a branch 150 feet long
and 6 feet in diameter.
This branch is bigger
than any single tree
east of the Mississippi River.
Eucalyptus regens
Tasmania, Australia, New Zealand
Tallest Angiosperms (330 feet)
http://noseeds.blogspot.com/2011/08/eucalypts.html
What Limit Tree Height?
• Water—how do trees carry water hundreds of
feet upward
• Mechanical Strength
– Height is related to cube diameter at base
– Double height—base increases 8X
• Energetic Cost of Maintaining Wood
• Root Support
Dynamic Model of Tree Growth
CO2
Limits to Shoot Growth
Access to CO2 and water and nitrogen
availability from roots.
Water & Nitrogen
Carbohydrates
Limits to Root Growth
Delivery of carbohydrates from shoot.
Root to Shoot Mass is generally 1:5
or 20% of Tree Biomass is below ground.
Water Transport in Trees
• Properties of water
• Why water transport is important?
• Stem & Leaf Vascularization
• Review of Cohesion Tension Model
Cohesion Tension Model of
Transpiration
• As leaf air spaces dry, water
evaporates from leaf cell
surfaces
• Water is pulled (under
tension) into leaf from
vessel elements & tracheids
• Water is replaced from
within cells and water
potential of the cell drops
• The weight of water in tall
trees is supported by
adhesion of water
molecules and cohesion
with organic molecules of
xylem
• Cellular water is replaced by
water from vessel elements
& tracheids where the
water potential is greatest
Experimental Evidence
of the Cohesion-Tension Model
of Transpiration
Predictions
*Xylem should be under negative pressure
* Xylem negative pressure should be
greatest during water stress
*Water tension should develop first in
twigs and later in branches and
trunk during day
Translocation
Experimental Observations
• Xylem tissue under
negative pressure
• Positive pressure forces
water back out of stem
Experimental Evidence
• Tissues shrink during the middle of the day when
transpiration is greatest
Experimental Evidence
• Transpiration flow in xylem occurs first in twigs near
leaves, followed by branches, trunk and roots
Problems at the Top
Limitations to Growth
in California Redwoods
What Limits Tree Height
in Redwoods?
• Water availability and tension
in xylem near tops-barely
overcoming gravity
• Growth is water limited near
top of tree
• Reduced photosynthetic tissue
in leaves near top
• Carbon dioxide gas exchange is
impeded near top of trees
How do redwoods approach/breach the maximum height of water tension?
Compare and Contrast
Growth Form of Boreal Conifers
with Temperate and Tropical
Broadleaved Trees
Broad-leaved Canopy Form--Laminar
•
•
•
•
Flat-topped, leaves oriented to absorb light
Few lower branches
Solar panels
High reflectivity of infrared radiation
– Used for vegetation modeling—healthy forests—chlorophyll
density
• Advantages:
– Highly efficient photosynthesis
– Rapid head dissipation
– Low maintenance respiration by having high canopy
• Disadvantages:
– High water loss
– Must live in moist, humid areas, with abundant direct light
• Network venation and vessel elements
Ratio of NIR to visible wavelength reflection is indicator of vegetation health
High NIR relative to VR—healthy
Low NIR relative to VR—unhealthy
Different ratios for coniferous and broad-leaved forests
Cirrus Digital Systems
Conifers of red pine and spruce have
low IR reflectivity and appear darker
than deciduous trees.
Pyramidal Growth Form of Boreal
Trees
• Flexible branches and
shape shed snow
• Northern Latitudes
– Short growing season
– Sun with low azimuth
– Shape allows for
photosynthesis when
sun is low in sky
www.mortonarb.org
• Conifers don’t have solar panel form to canopy, Why?
• Conifers don’t reflect as much IR as broadleaves
– Less healthy?
Lower chlorophyll content?
• Conifer forests tend to be very dark within canopy and on
forest floor.
• Could the shape of the trees improve light
aborption?
• Yes—anechoic formation
Anechoic (echo-free) Morphology
of Conifers
http://edbookphoto.photoshelter.com/image/I0000Vuyx1B.lEcc
Black Silicon
-highly absorptive molecular surface for solar cells
and light sensors
-form mimics conifer forests
World’s Quietist Rooms
anechoic design mimics conifers
Comparing Performance of Two Parking Lot
Populations of Tilia cordifolia
Park
Center
Professional
Studies
Comparing Performance of Two Parking Lot
Populations of Tilia cordifolia
• Are the populations of the same age?
• Performance indicators
– Tree size (DBH, Height, Width)
– Growth rate (twig growth, growth rings)
– Canopy density
– Other?
Adaptation of Anechoic Morphology
• Cone morphology of conifer shape and branches
• Increase light absorption
– Light and heat reflected down and within canopy
– Interior of canopy is 5-10o C warmer than exterior
• Extend photosynthetic period in northern regions
– Boreal forest—20% of land vegetation
• Disadvantages:
– High needle density—high respiratory costs—but
generally lower temperatures
– Lower photosynthesis rate because of xeromorphic
features of needles and tracheids
Flag Trees
Can you describe a mechanism that accounts for this growth form?
Wind
www.hiltonpond.org
http://errant-ronin.com/PrudhoeBayUshuaia/Photos
Umbrella Shape to Mediterranean Pines
Conifers that Behave like Broad-leaved Trees
Maximize sunlight, but reduce water loss by clustering of needles and branches.
Practical Applications of
Understanding Tree Form
Water & Transplant Shock
• 85-90% of roots damaged
– Not enough water to shoots
– Growers should root prune
periodically to encourage
heavy root growth near trunk
• Plant most trees in fall
– Root growth in fall and winter
– Carbohydrates are stored
• Used to regenerate roots
Root Growth Influences Shoot Growth
RPM Ecosystems
More Roots = Fast Trunk and Shoot Growth
More cytokinin production
More root surface area for
water and nutrient uptake
Important mycorrhizal partnerships
1 year old RPM produced roots
7 year old RPM and Conventional Trunks
Root Propagation Method
RPM Ecosystems--Dryden
• Select native, local
produced seeds
– Retain genetic variation
• Air-root pruning
– Shallow trays force tap
root into air, tap root
dies and encourages
lateral root growth
• Inoculate seedlings with
mycorrhizal fungi
1 year old Conventional Root Growth
The RPM Advantage
www.rpmecosystems.com
• RPM Trees Grow Faster!
–
The process promotes greater basal diameter, shoot length and root volume, resulting in a tree that
speeds to maturity three times faster than non RPM trees.
• RPM Trees Have Greater Survivability!
–
Because of the consistent size and health of RPM trees and the extraordinary development of their root
systems, survival rates in difficult field conditions approach 95% as compared with lesser survival rates of
conventionally grown trees.
• RPM Trees Produce Nuts, Seeds & Fruit Faster!
–
The RPM process results in trees that demonstrate early nut, seed and fruits production. Early nut
production is critically important for natural regeneration as well as food for wildlife. The RPM process
promotes greater basal diameter, shoot length and root volume, resulting in a trees that reach maturity
three times faster than non-RPM trees.
• RPM Trees Make Good Economic Sense!
–
•
RPM cultivated trees are cost effective and time-effective solutions for conservation and environmental
projects seeking to enhance success rates in growing healthier and hardier trees with accelerated growth
and regeneration characteristics, early fruit and nut production, and vastly improved survivability.
Dwarf Fruit Trees
• Slow growing roots
• Less water to support growth
• Lower cytokinin production in
roots also slows tree growth
• Trees mature at smaller size
Tree Growth Summary
• Limits to height
– Water
– Cohesion tension model
• Factors in growth form
– Environment
– Hormonal
• Roots and tree growth
– Transplant shock
– Dwarf trees
– RPM