Download How a Tree Grows

How a Tree Grows
J.G. Mexal
H/R 302
Spring 2005
Forestry & Society
How a Tree Grows• Trees are the 2nd largest organism- Eucalyptus
Sequoia
• Trees are the oldest organism-bristlecone pine (5,000 yrs)
Norway spruce (9,550 yrs)
• They can grow:
as much as 25 ft/yr
as little as 25 mm/yr (1”)
• They can survive:
10 ft of precipitation
10 in of precipitation
• They can survive:
>100oF temperatures
<-50oF temperatures
Trees live a long time!
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Alder
White birch
Sugar maple
Oak
Douglas-fir
Bristlecone pine
Norway spruce
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25 yrs
50 yrs
300 yrs
>500 yrs
>700 yrs
>2,000 yrs
>9,000 yrs
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How a Tree Grows• What does your tree look like?
– A 100 ft tree weighs about 4,000 lbs
– Has > 200,000 leaves (~120 lbs)
• Will shed 3,600 lbs of leaves in a lifetime
– Produce >5,000 seeds/yr
– Have 1,300 lbs of roots
– Require
• 8,000 lbs of CO2
• 2,900 lbs of H2O for Ps, and 5,000,000 lbs for Ts
– Generate over 8,000 lbs O2
Source: Ed Gilman, IFAS
Trees in the forest grow with one
trunk, and codominant stems
toward the top of the tree
Source: Ed Gilman, IFAS
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Comparison between forest tree and
landscape tree
Source: Ed Gilman, IFAS
Factors affecting tree growth
Genetic
Information
Environmental
Conditions
Physiological
Processes
Tree Growth
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How a Tree Grows-Functions
• Seed- reproduction
Bark
• Leaves- photosynthesis (carbon
capture)
• Roots- water & nutrient uptake
• Bark- protection
• Cambium/buds-growth
• Xylem- water transport (up) [dead]
• Phloem- carbohydrate transport
(down)
Cambium
Earlywood
Heartwood
Latewood
Sapwood
How a Tree Grows
Our secondary growth model:
A typical hardwood
tree in cross section
(transverse surface).
What can you identify?
Source: Ed Gilman, IFAS
The Bark:
The bark is
everything outside
the vascular
cambium.
As you can see,
there is a lot going
on in the bark.
Source: Ed Gilman, IFAS
The Bark: periderm:
Periderms form
the outer bark.
They are subdivided
further.
Source: Ed Gilman, IFAS
The Bark: periderm: phellogen (cork cambium):
The phellogen is the
region of cell division
that forms the
periderm tissues.
Phellogen development
influences bark
appearance.
Source: Ed Gilman, IFAS
The Bark: periderm: phellem (cork):
Phellem replaces the
epidermis as the tree
increases in girth.
Photosynthesis can take
place in some trees
both through the
phellem and in fissures.
Source: Ed Gilman, IFAS
The Bark: periderm: phelloderm:
Phelloderm is active
parenchyma tissue.
Parenchyma cells can
be used for storage,
photosynthesis,
defense, and even
cell division!
Source: Ed Gilman, IFAS
The Bark: phloem:
Phloem tissue makes
up the inner bark.
However, it is
vascular tissue
formed from the
vascular cambium.
Source: Ed Gilman, IFAS
The Bark: phloem: sieve tube elements:
Sieve tube elements
actively transport
photosynthates down
the stem.
Conifers have sieve
cells instead.
Source: Ed Gilman, IFAS
The Bark: phloem: companion cells:
Companion cells
provide sieve tube
elements with needed
metabolites.
Conifers have
albuminous cells
instead.
Source: Ed Gilman, IFAS
The cambium:
The cambium is the
primary meristem
producing radial
growth.
It forms the
phloem & xylem.
Source: Ed Gilman, IFAS
The Xylem (wood):
The xylem includes
everything inside the
vascular cambium.
Source: Ed Gilman, IFAS
The Xylem: a growth increment (ring):
The rings seen in
many trees
represent one
growth increment.
Growth rings
provide the texture
seen in wood.
Source: Ed Gilman, IFAS
The Xylem: vessel elements:
Hardwood species have
vessel elements in
addition to trachieds.
Notice their location
in the growth rings of
this tree
Source: Ed Gilman, IFAS
The Xylem: fibers:
Fibers are cells with
heavily lignified walls
making them stiff.
Many fibers in
sapwood are alive at
maturity and can be
used for storage.
Source: Ed Gilman, IFAS
The Xylem: axial parenchyma:
Axial parenchyma is
living tissue!
Remember that
parenchyma cells can
be used for storage
and cell division.
Source: Ed Gilman, IFAS
The Xylem: rays (multiserrate & uniserrate):
Rays are radial
parenchyma cells.
Parenchyma cells
give rise to
adventitious tissues.
Source: Ed Gilman, IFAS
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How a Tree Grows/Diffuse vs Ring Porous
Silver Maple
White Oak
Ring Porous
Diffuse Porous
50X
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How a Tree Grows-Idealized
Leaves
leaves
A tree can produce
200,000 leaves/yr
Annual rings
Taproot
Lateral root
Fruitfruit
Woody Stem Structure
Shoot Growth
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Shoot Growth in Eastern White Pine
Terminal growth = 44 cm
Biomass Partitioning/ Nelda Methany 2005
Percent
100
90%
Wood
35%
35%
30%
Leaves/Roots
5% 5%
Fine Roots
3
7
20
Time (yrs)
55
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How a Tree Grows
• Growing regions or meristems
– Buds- height, flowers, leaves, (roots)
– Cambium- diameter
– Cork cambium - bark
• Factors
– Temperature
– Light
– Water
Tropics vs
Boreal
Where a tree grows!!
20”
80”
Dry tropical forest
Desert
140”
oF
86
Tropical forest
59
32
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Urban Forestry CO2 capture
Basic Photosynthetic Reaction
• CO2 + H2O
• 1.47 lb 0.60 lb
λ
CH2O + O2
1.00 lb
1.07 lb
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How a Tree Grows/
Kozlowski & Pallardy 1999
clear day
overcast day
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How a Tree Grows
• Most forests are regenerated sexually
– seeds are required
– exceptions: aspen, oak, eucalyptus
• Environmental factors:
– light (forest gap)
– moisture (mineral soil)
– temperature (dormancy & germination)
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How a Tree Grows - Piñon
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Flower primordia (buds) form in fall (yr-1)
Flowers develop in spring (yr-2)
Pollination occurs
Drought
Overwinter
Fertilization occurs in spring (yr-3)
Growth of cone
Maturation of cone with seeds in fall
Total time elapsed >24 mo.
Pine life cycle
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How a Tree Grows/
Reproductive Cycle of Pinus contorta (Owens & Molder 1984)
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How a Tree Grows-female cones
maturation
Pinus elliotii (slash pine)
fertilization
pollination
24 mo.
12 mo.
1 mo.
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Pinus eldarica cone
Rachis
Viable seed
Empty seed
Bract
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Pine seed size variation
wing
Pinus pinea (Italian stone pine)
Pinus nigra (Japanese black pine)
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How a Tree Grows-Germination
Nothofagus in Chile
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Seed is dispersed
Overwinters (dormant)
Germinates
Growth commences
• 10,000,000/ac
• 4,000,000/ac
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4,000/ac @ 25 yrs
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100/ac @ 100 yrs
0.001%
Ponderosa pine seed rain following harvest-CO /
Logged ’80-’81 winter
WJAF 21(1):19:06
Seeds/m2
Seedlings/m2
100
20
90
18
80
16
Shelterwood
14
4
10
2
0
0
81
83
85
87
89
91
93
95
97
99
1
Year
1
20
99
6
97
30
95
8
93
40
91
10
89
50
~48% of seed consumed
by animals regardless
of year
87
12
81
60
85
Seedtree
83
70
Germination
Survival
Dendrochronology
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Xylem production- earlywood vs latewood
Phloem
3,4 = Latewood cells
1,2 = Developing xylem cells
L = Preceeding year
5 = Earlywood cells
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Silviculture/Response to Thinning
Juniper/NM
False rings
Wider rings
10 mm
Competition
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Dendrochronology/Skaptar Jokull Volcano eruption in
Iceland causes ‘the summer that wasn’t’ in western
Alaska. (http://abcnews.go.com/sections/science/DyeHard/dyehard.html)
Earlywood
Eruption occurs June 8, 1783
No Latewood, indicating very
early onset of winter
Latewood
Review Questions
• Define: xylem, conifer, phloem, hardwood,
cambium, softwood, cord, evergreen, board foot,
deciduous, basal area, MAI, CAI, PAI, closed
forest, earlywood (spring wood), latewood
(summer wood), dendrochronology, false ring
• What environmental factors affect seed production
germination? Why does piñon have good seed
crops every 4-5 years?
• Describe the basic process of photosynthesis.
• Why do trees produce so many seed, yet so few
germinate?