Module 2 Forest Ecosystem structure and function

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Module 2Forest Ecosystem structure and function
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FOREST ECOLOGY

• Just how does it pertain to forest stewardship
  planning

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Forest ecology effectsAll Resource Categories

• Forest health
• Timber and wood products
• Soils
• Water
• Fish wildlife

• TE species, cultural resources
• Esthetics recreation
• Agro-forestry spl. forest prod.

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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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Another example ecosystem.
Exhaust out
Diesel O2 in
Animate object in cab
Trees in
Internal interacting interdependent systems
Logs out
External interactions interdependencies
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Ecosystems vary in scale. Depends on what were
interested in.
Douglas-fir needle
Harvest setting or stand
cull log
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Ecosystems on a landscape scale watersheds,
timbersheds, spotted owl smas
Photo Oregon State University College of Forestry
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Until interplanetary travel becomes cost
effective..
Photo Oregon State University College of Forestry
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Ecosystems have Structure Function

• Structure
• How is it put together?

• Function
• What does it do

Different structures Different functions.
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Ecosystem structure (sizes and arrangement of
plants, animals, dead stuff et al.)
Op. Env.
Ecosystem function (the operational environment,
exchange of matter and energy)
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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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Operational environment

• BIG drivers
• climate
• elevation, slope, aspect
• geology soils
• land conversion
• fire policy
• floods
• biota

• Not so big drivers
• timber harvest
• silviculture
• land conversion
• microclimate
• landslides
• floods
• plants animals

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which leads towhy are plant species found where
they are found?

• Answer its evolved adaptation to its surrounding
  operational environment

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SO, HOW DO I KNOW WHAT MY TREES ARE?
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and.Ecological communities

• Plants and animals occurring together in a
  coherent group because of their adaptations to
  each other and the surrounding environment
• (Communities become ecosystems when we include
  processes behind interaction and interdependency)

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Physiographic and geologic provinces of
Washington (Franklin and Dyrness 1973)
BLUE MOUNTAINS
COAST RANGE
BLUE MOUNTAINS
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Temperature and water availability are the two
big drivers in determining forest type Fire is
important Geology, e.g. serpentine soils, may be
locally important
Figure USDA forest Service
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How does your forest type affect your forest
management goals?

• ______________________________
• ______________________________
• ______________________________
• ______________________________

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Lets take a closer look at some natural forces..
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Natural forces (disturbances) modifying the
operational environment

• volcanoes
• landslides
• floods
• and

• wind throw
• root disease
• global climate change

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Fire, natural and human caused, is a major force
driving plant succession in North American
forests Some trees and shrubs are adapted to
fire, while others are not
Photo courtesy Bureau of Land Management
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I
F
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Pre-settlement fire intensity and frequency
Adapted from USDA Forest Service, Dr. James
Agee UW COF
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Before fire suppression, east-side fires were
typically low intensity and fairly frequent
ground fires, leading to open stands of ponderosa
pine and larch over much of the landscape.
Photo courtesy Bureau of Land Management
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West-side fires tended to be infrequent,
catastrophic stand replacing fires. Due to fire
suppression and fuels buildups, atypical
catastrophic fires now occur on the
east-side. Timber harvesting is one way to
reduce fuel loads in east-side stands to less
damaging levels.
Photo courtesy Bureau of Land Management
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Due to air quality regulations and loss of
trained agency personnel, prescribed fire, as
shown here, is used less frequently.
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Forest successioncommunity changes because
plants change the operational environment
See Forest Ecology in Washington handout
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Forest succession

• Primary succession follows big disturbance
• Early seral plant species
• Best in full sunlight conditions

• Secondary succession after initial plant
  community
• Late seral species
• Best tolerate shade and other understory
  conditions

See Forest Ecology in Washington handout
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Shade is less intense under red alder, favoring
slow natural establishment of western red cedar
and western hemlock over Douglas-fir
The intense shade under this salmon berry seems
to prevent even shade tolerant species from
getting established here without some kind of
disturbance
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Forest succession

• the changed operational environment may help
  perpetuate the existing plant community, OR, set
  the stage for the next community.

Shasta red fir seedling
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Succession in an even-aged Douglas-fir forest
Where is your forest headed?
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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How does succession affect your forest management
goals?

• ______________________________
• ______________________________
• ______________________________
• ______________________________

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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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Productivitywhat makes the whole works run?
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Foliage
Boles branches

Below ground
2.46
LOW SITE HIGH
SITE Photosynthate allocation and site quality
(Perry 1994)
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Leaf Area Index
An acre of highly productive forest may have 12
or more acres of leaves over it
wheres there most available water and good
temperatures, theres greatest productivity
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Trophic levels

• T1 Producers
• T2 Herbivores
• T3 Primary Carnivores
• T4 Secondary Carnivores
• T5 Decomposers

Energy flows are like log processing theres an
attempt to maintain maximum value at every step,
or ecologically, nature tends to fill all niches
with communities
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the T1 level

• The environmental drivers determining species
  location also determine productivity. Soils
  management is very important.

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Nice little T2 Herbivores at work The western
spruce budworm is a serious pest on east-side
forests overstocked with true firs and Douglas-fir
Photo Natural Resources Canada, Canadian Forest
Service, http//www.pfc.cfs.nrcan.gc.ca/entomology
/defoliators/budworms/west_spruce_e.html 20041119
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Decomposers (T5) are essential within a forest
ecosystem for nutrient cycling Decomposers
include larger insects, and a fantastic variety
of microscopic insects, bacteria, fungi and
actinomycetes
Photo Dr. A. Moldenke, Oregon State University
Photo Dr. A. Moldenke, Oregon State University
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Mycorrhizae Symbiotic fungi that infect tree
roots

• Mutual benefits
• Greatly expanded root network (increased water,
  nutrients)
• Essential hormones
• Pathogen protection
• Attracts microscopic insects for bug poop near
  roots
• Fungi get food from tree

White stuff is mycorrhizal hyphae
Photo Dr. R. Molina, Oregon State University
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What happens within and around a primary root?
Fungi infect this blue layer of cells
Water, dissolved nutrients and hormones carried
up to needles in xylem cells (wood)
Fungal hyphae connect root with water and
nutrients on soil particles
Photo Dr. R. Molina, Oregon State University
Root hairs also help
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Which critters at which trophic levels affect
your forest management goals?

• ______________________________
• ______________________________
• ______________________________
• ______________________________

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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 within between species
• 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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Sustainability is like good equipment operation
maintenance. Even better, with good
harvesting practices, forest ecosystems can
quickly repair themselves.
as is leaving enough of the right pieces intact.
The right machinery and a knowledgeable operator
are very important
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Trees and forests are a renewable and sustainable
resource These logs are the first commercial
thinning of a stand planted by the logger when he
was in high school on a brushfield cleared by his
father.
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Within stands or across landscapes,
sustainability takes human ingenuity working with
Mother Nature
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