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PART FOUR - Forest Resources
Tree Harvesting - 1. Clear Cutting
• forest harvesting
that removes all
trees from an
area.
• Includes desirable
AND undesirable
species
• the land is left
uncovered.
• P. 165
Advantages
 Most rapid
 economical
 and least dangerous form of
harvesting.
1. Clear Cutting
Disadvantages
– Leaves behind a
poor looking
landscape.
– Ecosystem has a
very difficult time
recovering.
– Soil is
defenseless to
erosion.
Especially
sloped land
– Wildlife habitats
are disturbed.
Tree Harvesting – 1. Clear Cutting
Tree Harvesting – 2. Strip Cutting
a variation on clear cutting where strips of forest about 1 or 2
ha are left between the clear cut areas.
2. Strip Cutting
Advantages
 Less ecological disruption than clear cutting.
 Soil erosion is less severe.
 Forest can regenerate naturally without human help.
Disadvantages
 Requires a larger section of forest to produce
the same amount of yield.
 More disruption to the ecosystem. Ex: extra
roads.
Tree Harvesting – 3. Selective Cutting
• forest
harvesting that
removes only
mature trees
and leaves the
other trees in
place.
• Immature trees,
undesired
species and
underbrush is
all left intact.
3. Selective Cutting
Advantages
 Leaves the biggest portion of the forest
intact.
 Causes the least ecological disruption.
Disadvantages
 Most expensive method.
 Yields are lower.
 Care must be taken to avoid damaging unharvested trees.
 Roads must be maintained longer to keep harvesting
mature trees.
• The removal
of a forest by
cutting and/or
burning,
• the land is put
to a nonforest use…
• Ex. farms,
grazing
pastures
residential or
industrial
sites, roads,
etc..
Deforestation – p. 163
Deforestation
 Approx. 1/3 of the earth's land masses are covered in
forest.
• Forests and trees can be
used for things like:
Some values of our worlds
forests are:
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building materials
home heat
recreation
paper.
biodiversity
medicine/pharmaceuticals
animal habitats
food for animals
air purification
water retention
soil maintenance
Importance of the Forests
• Forests prevent soil erosion through the use of their
roots (roots hold the soil together).
• Prevent flooding… Trees take up much of the water.
• Prevent soil from drying up… SHADE soil and forest
floor from warm temps.
• Wind break that prevents wind erosion… Wind
would blow the soil away…epsecially dry soil.
Importance of the Forests
• Forests also add decaying material to the soil
(humus content) otherwise the soil would have less
to no nutrients.
• Help filtrate the water.
• Recycles air…CO2 into O2.
• Base of the food chain for many ecosystems.
Extensive Deforestation – The Reasons!?!?
• Expanding needs in
agriculture (#1
reason)
• Urbanization
• Mining operations
• Hydroelectric
operations - flooding
the land
• Logging, lumber,
building materials
“Rates of Deforestation World Wide” (pg.164)
Between the TROPICS….
Deforestation - Latin America
• Developing nations of the world.
• forests cleared or lost due to hydroelectric projects to provide
electricity to an increasing number of people.
• Large scale cattle ranches and urbanization have also
contributed to deforestation.
• The cost of “modernization”!!!!
Deforestation - Latin America
Deforestation - Africa
• Poorer, under-developed region of the world.
• making room for subsistence farming to support the growing &
hungry population.
Deforestation – Asia
• A growing population!!!
• The forests are cleared for housing and for agricultural land to
feed the people.
Sustainable Forestry
• Sustainable means to manage or
maintain something so that it
remains and provides benefits
over the LONG term.
• Sustainable forestry… is a
method of harvesting AND using
the forests so that the resource is
not depleted or permanently
damaged.
FACT
• If we cut trees faster than they
grow back, we will run out of
trees... NO KIDDING!!!
Jeopardizing “Sustainable forests!”
WORLD POPULATION INCREASES CAUSES:
• The demand for forestry products increases (It is a
RESOURCE with value)
• the demand for forestry land to be converted to other
uses…housing, mining, and hydro-electricity projects, etc..
Sustainable Forestry…HOW??
From a “Systems Model” perspective:
1. Improve what we input into forestry (replanting & seeds)
2. Improve processes like:
o road construction
o harvesting techniques
o environmental protection actions
o reducing losses (use all of the tree)
3. Reduce the need of output product Or even Maximize use.
o Recycle, use all parts, reduce wastage etc..
o Use of alternate building materials
Clear Cutting
Controversy
(handout)
Forests and Climate
• Warm/hot & wet, 365 days of
growth!! = more diversity, largest &
tallest trees, usually broad-leaved
trees. (Tropical Rain Forest)
• Driest or coldest = less diversity,
fewer, shorter and smaller trees or
even grasses usually specially
adapted. (Tundra, Desert or
Grasslands)
• In between!!! (US!)…temperate
regions, winter & summer seasons,
mixed forests (broad-leaved &
coniferous trees)
Case Study
• “Tree Harvesting in Various
Ecosystems”
• Pg. 166
• Question #9