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Forest Dynamics:
Growth, Loss, Regeneration
November 2004
Overview
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Is deforestation real?
Why care about forests?
Forest functions and processes
Current research
Management strategies
Consumption practices
Stout Grove in
Headwaters Forest
Is Deforestation Real?
Headwaters Forest
Headwaters Forest
Headwaters Forest
Headwaters Forest
Humboldt State Park
Is Deforestation Real?
• Who has the right answer?
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Environmental Advocacy groups
Forest industry
Government Agencies
Scientists
• With what time in the past do we compare
the present?
Is Deforestation Real?
Forest cover globally has declined from an estimated
62,203,000 sq km to 33,363,000 sq km (54% loss) in the
past 8000 years. 4,500,000 sq km or 7% of the original
cover lost between 1960 and 1990
Forest cover in Indochina is estimated to have declined
from 70% in 1945 to 25% in 1995
Redwoods cover about 2 million acres in a coastal strip 5
to 35 miles wide from extreme southwest OR to around
Big Sur. Cover has remained the same or perhaps even
slightly increased but only about 74,000 acres of this is
old growth-a 95% loss in old growth
Many forest or old growth dependent species endangered
or extinct: Coho Salmon, Marbled Murrlet, Spotted Owl
Remaining “Original” Forest (WRI)
World Forest Loss (WRI)
Human Footprint
(Sanderson, Jaiteh, Levy, Redford, Wannebo, & Woolmer; BioScience 2002)
Forest Loss 1990-2000 (FAO)
0.20
% Forest Cover Loss 1990-2000
0.10
0.00
-0.10
-0.20
-0.30
-0.40
-0.50
-0.60
-0.70
-0.80
Total Total Asia Total
Total Canada
Africa
Oceania Europe
United
States
Total
North
and
Central
America
Brazil
Total TOTAL
South WORLD
America
Legend
Old Growth
Second Growth
Legend
Old Growth
Second Growth
National Park or Forest
State or Local Park or Forest
Arcata
Eureka
Fortuna
Scotia
Weott
Acres Old Growth Redwood
2250000
2000000
1750000
1500000
1250000
1000000
750000
500000
250000
0
1800
1820
1840
1860
1880
1900
1920
1940
1960
1980
2000
Sources: Snyder 1992, Barbour et al. 1993, 2000 estimate by Willett
But there’s more trees now than ever!
• Important forest characteristics include:
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Density = number of trees per area
Frequency = how common
Dominance = how big
Diversity = how many kinds of trees
Structure = fallen logs, snags, understory
• There may be more trees but that’s not all
that’s important
Why care about forests?
• Forests prominent in myth and religion as places of
fear, enlightenment, and mystery
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Hansel and Gretel experienced the forest as frightening
St. Hubert the Jagermeister received vision in forest
Odin crucified on the Tree of Life, Yggdrasil, an ash tree
Lord of the Rings
Buddha attains enlightenment under a tree
• Generally, humans see forests as wild, magical
places that must be tamed for civilization to progress
Buddhist Monks at Bodhi Tree
(The site of Buddha's enlightenment)
Why care about forests?
• Forests are beautiful
• Over 3.5 million people per year from around the
world visit Yosemite
• Proximity to forest increases value of houses
• Trees planted in urban settings such as streets and
parking lots for aesthetic value but also reduce
carbon monoxide pollution and temperature
Why care about forests?
• Food
– Nuts, fruits, roots, mushrooms, game, grubs
• Medicine
– Aspirin from willows
– Taxol (anti-cancer drug) from Pacific Yew once
removed from managed forests as a “junk” tree
– Lady’s Slipper orchid, sedative, now endangered from
habitat loss and over harvesting
• Carbon fixation and reduction of earth’s albedo
(reflectivity) influences global warming
• Locally increases precipitation
• Stabilizes soil with root structure
• Habitat for game and non-game species
Why care about forests?
• Wood
– Fuel; wood is the primary heating and cooking
fuel for most humans for most of our history
including the present time
– Fiber = rayon, paper (could use other plants)
– Timber for homes, decks, fences, paneling,
chopsticks, and toothpicks
– Chemicals including turpentine and vanillin
Why care about forests?
• Since ancient times, humans have protected
certain forests or trees as sacred sites and
for game and timber
– Sacred groves of the Druids
– King’s woods poached by Robin Hood
– Select trees in the American colonies protected
for use as masts in English naval vessels
Causes of Deforestation
• Commercial logging
• Clearing for agriculture such as coffee, bananas,
pastureland for livestock
• Mining
• Oil and Gas Development
• Hydroelectric dams
• Housing development (often preceded by agriculture)
• Cutting for fuel wood
• Mechanization of logging
• Increasing population and per capita resource use
• Diseases and pests ie. Phytophtora ramora
– www.suddenoakdeath.org
• “Myth of Superabundance” -Udall, former Secretary of
the Interior
Community Formation
• Community = a group of associated organisms
living in proximity at the same time
• Succession = a change in species composition
over ecological time, not speciation
• Secondary Succession = succession that occurs
after a catastrophe destroys a community but
leaves soils intact ie. fire, flood
• Primary Succession = succession that occurs after
a catastrophe destroys a community and wipes out
soils ie. glacier, volcanoes (Mt. St. Helens)
• Seral stage = phase of succession such as
early, mid, climax
Exposed
rocks
Lichens
and mosses
Small herbs
and shrubs
Heath mat
Time
Jack pine,
black spruce,
and aspen
Balsam fir,
paper birch, and
white spruce
climax community
Mature oak-hickory forest
Young pine forest
Annual
weeds
Perennial
weeds and
grasses
Shrubs
Time
Secondary Succession
Grass

Shrub

Tree
Secondary Succession
Disturbance
• Gradual
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Minor fire
Tree falls
Herbivory
Disease
• Catastrophic
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Major fire
Flood
Glacier
Volcano
Huge comet smashing into the earth
Disturbance and Management
• Patch Dynamics = Disturbances can create gaps in
dominant trees that allow other species a chance to
grow resulting in a greater variety of species
• Many trees depend on fire to reproduce
– Giant Sequoia (Sequoiadendron giganteum)
– Knobcone Pine (Pinus attenuata)
• These factors lead managers to allow or create
disturbances such as “controlled” burns
Fire Management and Politics
• Los Alamos, NM Park Service 2000 burn went
awry
• Wildfires of 2001-2002 and 2003 blamed on
environmentalists accelerating “Healthy Forest
Initiative”
• "Past fire suppression is not to blame for causing
large shrubland wildfires…Under Santa Ana
conditions, fires carry through all chaparral
regardless of age class. Therefore, prescribed
burning programs … are futile at stopping these
wildfires." -Dr. Jon Keeley, USGS fire researcher
Vertical Structure
Canopy/Overstory
Understory
Shrub
Herb
Litter
Root
Spatial Diversity
Temperate v. Tropical
Far from equator
Near equator
Few species
Many species
Rich, deep soils
Poor, thin soils
Seasonal food supply
Constant food supply
Industrial nations
Developing nations
Old Growth, Second Growth, Tree Farms
• Old growth = mature forest not greatly disturbed
by humans with native species composition and
complete structural components; exact definition
is controversial
• Second Growth = regenerated forest following
anthropogenic (human caused) catastrophe
• Tree Farms = managed for timber, regularly
disturbed
Clear Cut v. Select Cut
• Clear cut = cutting all trees in an area and
removing all cover
– favors sun tolerant species
– exposes soil to erosion
– reforestation can fail
• Select cut = cutting a selected portion of trees
leaving much to little cover
– Better preserves soil and genetic integrity
– permanent roads
– more frequent disturbances
Forest Symbioses
Symbios = two organisms of different species
where at least one affects the other’s
resource acquisition or reproduction
– Mutualism=both benefit (+ +)
– Parasitism=one benefits, one suffers (+ -)
– Commensalism=one benefits, other unaffected
(+ 0)
– Competition = both suffer (- -)
– Amensalism=one suffers, other unaffected (- 0)
– Neutralism=both unaffected (0 0)
Forest Symbioses
• Most plants form mutualistic mycorrhizal
(myc = fungus, rhiz = root) associations
which aid growth and can even result in
nutrient transfers between two different
plant species connect to a common fungal
associate
Forest Symbioses Examples
• Trees, mushrooms, rodents, and bugs
Vole
Flying Squirrel
Collembolan or Springtail
Forest Symbioses Examples
• Trees, mushrooms, rodents, and bugs
• Trees and Fish
• Trees and Cicadas
Conservation and Sustainable Management
• Goal = maintain a stable ecosystem with native
species, genetic integrity, and intact processes
• Island biogeography (MacArthur and Wilson
1967) suggests management for remnants
– 90% loss in habitat leads to a loss of half of occupying
species
• Large undisturbed tracts definitely beneficial
• Buffer zones of degraded but protected land
around prime native habitat
• Connecting isolated reserves with wildlife
corridors increases genetic flow but also aids
predators and diseases
Forest Preservation Strategies
• Change policies, laws, taxes, and funding to create incentives to
protect and restore critical habitat
– Public-lands logging dropped from12 billion board feet in
the 1980s to around 2 billion b.f.
– Healthy Forest Initiative
– Sierra Plan
– Coho listing
• Government (parks, reserves) or private (TNC) entities
• Change consumption practices
– 2 million community college students using 50 pieces of
paper per semester = 8,430 trees or a piece of forest about
the area of a neighborhood of 70 homes
– 100 million people * .03 lbs/cup * 5 days/wk * 48 wk * 17
trees/2000lbs = 6,120,000 trees/year in paper cups
Wood Alternatives
• Use something else
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Steel frame, straw bales, adobe for houses
Recycled plastic decking and fencing
Bamboo instead of oak for floors
Hemp, kenaf, cotton, rice for paper
Use recycled or scrap wood
Use FSC certified “sustainable” wood
Don’t use paper cups, wood chopsticks, etc.
Consume organic bananas and shade grown coffee
Terrence Willett
[email protected]
Notes for this presentation are available at:
www.gavilan.edu/research/deforestation.pdf