Forest Ecology

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Forest Ecology
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What exactly is Forest Ecology?

• Ecology The study of the interrelationships
  between living organisms and the animate and
  inanimate world around them.
• Forest Ecosystem Living things and non-living
  things in the forest

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• Ecosystems are not more complicated than we
  think, they are more complicated than we can
  think
• Jack Ward Thomas, former Chief, US Forest Service

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Ecosystems consist of
Communities of animate (living) things plants,
animals, microbes, et al.
Inanimate stuff (rocks, soils, gasses, chemicals)
Exchange matter and energy Within the
system Between systems

• Systems interact and are interdependent

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Scales Vary
Landscape Level..
Stand Level..
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Ecosystem Properties
Structurehow is it put together?
Functionwhat does it do?
Change.differences in structure and function
over time
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operational environment the physical
environment around a living organism governs how
ecosystems interact and function
mechanical
light
chemical
heat
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Operational environment affects everything

• Growth
• Disease
• Insects
• Reforestation
• Distribution of plant and animal species

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why are plant and animal species found where they
are found?

• Answer evolved adaptation to their surrounding
  operational environment

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Ecological communities

• Plants and animals occurring together in a
  coherent group because of their adaptations to
  each other and the surrounding environment

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Physiographic and geologic provinces of
Washington (Franklin and Dyrness 1973)
BLUE MOUNTAINS
COAST RANGE
BLUE MOUNTAINS
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Cascade Mtns
The Pacific Ocean
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Orographic lifting
Drier rainshadow
Prevailing Winds
Ocean
East
West
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Temperature and water availability are the two
big drivers in determining forest
type Disturbances are also important, especially
fire. Geology, e.g. serpentine soils, may be
locally important
Figure USDA forest Service
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Temperature and moisture differences result in
big differences in vegetation
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Some of our common native trees

• Douglas-fir
• Ponderosa pine
• Grand fir

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Douglas-fir

• Probably our most important tree!
• Common both east and west of Cascades
• Can grow very large
• Long-lived
• Distinctive cones
• Shade-intolerant
• Thick-corky bark on older trees

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Ponderosa Pine

• Grows in drier climates, east of Cascades
• Can grow very large
• Long-lived
• Shade-intolerant
• Thick bark on large trees
• Drought-tolerant

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Grand fir

• Grows in drier climates, east of Cascades and in
  valley bottoms west of Cascades
• Can grow large
• Shade-tolerant, can grow in its own shade
• Thin bark
• Not as long-lived

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Other conifers

• Western Larch

• Western White Pine

• Western hemlock

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Hardwood Species

• Black Cottonwood

• Bigleaf Maple

• Oregon White Oak

• Red Alder

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Forest Succession
Shade-intolerant Trees dominate
Light-loving shade-intolerant Trees establish
Grass-forb-shrub
Time
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Forest Succession
Shade-tolerant trees can become a major stand
component given enough time
Shade-tolerant Trees develop in understory
Time
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Forest Succession
Conversion to shade tolerant tree species
Mostly shade intolerant plant species
Figure from Washington State University
Cooperative Extension
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Succession may have many end points

• 45-year-old Douglas-fir stand (Idaho)
• Root disease and bark beetles affected outcome
• Susan K Hagle, USDA Forest Service, Western
  Forester, 2002

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Disturbances
Fire Logging Windthrow Insects Disease Volcanic
eruptions
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Before fire suppression, Eastern Cascade fires
were typically low intensity and fairly frequent
ground fires, leading to open stands of ponderosa
pine and larch over much of the landscape.
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Disturbances alter Forest Succession
Ponderosa pine and Douglas-fir
After frequent, low-intensity fire
Grand fir
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Smokey Bear and Selective logging
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West-side fires tended to be infrequent,
catastrophic stand replacing fires.
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I
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Fire Intensity
Fire Frequency
Pre-settlement fire intensity and frequency
Adapted from USDA Forest Service, Dr. James
Agee UW COF
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Controlled burning (Prescribed fire) can be used
to mimic the role of fire on the east side
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Due to air quality regulations and lack of
trained personnel, prescribed fire is used less
frequently. Physical removal, via commercial
thinnings or non-commercial thinnings, is often
used to mimic the effects of fire
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What about human induced ecosystem changes?
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Harvesting affects the operational environment.
Heregreatly increased light, heat, water,
chemical turnover soil compaction?, mycorrhizal
effects?
forest succession is restarted
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Thinning effects less increase in light, heat,
water, nutrient turnover mechanical damage to
leave trees?, soil compaction?
forest succession may be accelerated
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Ecosystem resilience sustainability

• Our Pacific Northwest forest ecosystems are
  adapted to various types of natural disturbances.

Photo Washington DNR
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Understanding Resiliency disturbance does not
exceed system ability to recover self healing

• redundancy
• genetic diversity
• refugia

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Sustainability

• Sustainability is meeting present needs without
  compromising the future.
• Not pushing an ecosystem beyond its ability to
  recover

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Practices that drastically alter the operational
environment, such as terracing for site
preparation, can be successful, though not
politically acceptable
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Legacies (the local spare parts bin)

• As long as enough undisturbed ecosystem pieces
  remain, the system will recover

Photo Oregon State University College of Forestry
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To keep every cog and wheel is the first
precaution of intelligent tinkering.
Aldo Leopold
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OK then, what the heck does this mean to me?

• Dont manage a stand outside its range of
  ecological variability
• Stands heavy to shade-tolerant species
  (particularly on the east side)
• Manage stand density thin
• Vary whatever you do! Mother nature is not
  uniform
• Manage for a variety of structures leave some
  larger trees, logs, shrubs save the pieces

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Once you learn to read the land, I have no fear
of what you will do to it, or with it. And I know
many pleasant things it will do to you.
Aldo Leopold
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Adapted From