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Chapter 10
Sustaining Terrestrial
Biodiversity: The Ecosystem
Approach
Human Population
Size and resource use
Human Activities
Agriculture, industry, economic
production and consumption, recreation
Direct Effects
Degradation and destruction Changes in number and
of natural ecosystems
distribution of species
Alteration of natural chemical Pollution of air, water,
cycles and energy flows
and soil
Climate
change
Indirect Effects
Loss of
Biodiversity
Fig. 10-2, p. 192
Human Impact on Terrestrial
Biodiversity

Why should we care?


Intrinsic value:
Instrumental value:
Managing and Sustaining
Forests

3 types of forests based on age:

Old-growth forests:
Second growth forests:
Tree plantation or tree farms:

Governments own 84% of forests


Weak trees
removed
Clear cut
25
30
Seedlings
planted
15
Years of growth
10
5
Fig. 10-6, p. 195
Natural Capital
Forests
Ecological
Services
Support energy flow
and chemical cycling
Reduce soil erosion
Absorb and release
water
Economic
Services
Fuelwood
Lumber
Pulp to make paper
Mining
Purify water and air
Livestock grazing
Influence local and
regional climate
Recreation
Store atmospheric
carbon
Jobs
Provide numerous
wildlife habitats
Fig. 10-4, p. 193
Managing and Sustaining
Forests

Estimate: worlds forests are being
cleared or degraded exponentially at a
rate of 0.3-0.8%/year.

Most is used for fuel wood in developing
countries. Ex- Haiti used to be covered
in forests but now only 2% of land is
covered in trees.
Managing and Sustaining
Forests

Solutions:



1. Plant small plantations of fast growing
fuel wood trees and shrubs (community
forest)
2. Burn wood more efficently by providing
people with cheap, more efficient and
less polluting wood stoves or solar ovens.
3. start burning renewable sun-dried
roots of various plants
Managing and Sustaining
Forests

Harvesting trees

Causes damage by:






Building roads
Increases erosion
Sediment runoff
Habitat fragmentation
Biodiversity loss
Invasion of non-native species, pests,
disease
Harvesting Trees

Trees can be
harvested individually
from diverse forests
(selective cutting), an
entire forest can be cut
down (clear cutting), or
portions of the forest is
harvested (e.g. strip
cutting).
Figure 10-9
Natural Capital Degradation
Deforestation
• Decreased soil fertility from erosion
• Runoff of eroded soil into aquatic systems
• Premature extinction of species with
specialized niches
• Loss of habitat for native species and
migratory species such as birds and butterflies
• Regional climate change from extensive clearing
• Release of CO2 into atmosphere
• Acceleration of flooding
Fig. 10-7, p. 196
Solutions
Sustainable Forestry
• Identify and protect forest areas high in biodiversity
• Grow more timber on long rotations
• Rely more on selective cutting and strip cutting
• Stop clear-cutting on steep slopes
• Cease logging of old-growth forests
• Prohibit fragmentation of remaining large blocks
of forest
• Sharply reduce road building into uncut forest areas
• Leave most standing dead trees and fallen timber for
wildlife habitat and nutrient recycling
• Certify timber grown by sustainable methods
• Include ecological services of forests in estimating
their economic value
• Plant tree plantations on deforested and degraded land
• Shift government subsidies from harvesting trees to
planting trees
Fig. 10-12, p. 199
Managing and Sustaining
Forests

Forest Fires

Surface fires:


Crown fires:


Advantages: help prevent worse fires,
release nutrients, release some seeds, and
control pathogens
Can kill wildlife
Prescribed fires:

Helps clear leaf litter.
Trade-Offs
Logging in U.S. National Forests
Advantages
Disadvantages
Helps meet country’s
timber needs
Provides only 4% of timber
needs
Cut areas grow back
Ample private forest land
to meet timber needs
Keeps lumber and
paper prices down
Has little effect on timber
and paper prices
Provides jobs in
nearby communities
Damages nearby rivers and
fisheries
Promotes economic
growth in nearby
communities
Recreation in national
forests provides more local
jobs and income for local
communities than logging
Decreases recreational
opportunities
Fig. 10-14, p. 202
Tropical Rainforest
Deforestation and Degradation

Deforested to:





Build infrastructure
Set up cattle ranches/crops
Logging
FYI: loose 50,000-170,000 km/yr. Less
then 5% of TRF are managed sustainably
Why should they be protected

Medicines!!!
Solutions
Sustaining Tropical Forests
Prevention
Protect most diverse and endangered
areas
Restoration
Reforestation
Educate settlers about sustainable
agriculture and forestry
Phase out subsidies that encourage
unsustainable forest use
Add subsidies that encourage
sustainable forest use
Rehabilitation of degraded
areas
Protect forests with debt-for-nature
swaps and conservation easements
Certify sustainably grown timber
Reduce illegal cutting
Reduce poverty
Slow population growth
Concentrate farming and
ranching on already-cleared
areas
Fig. 10-20, p. 207
Managing and Sustaining
Grasslands
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Rangelands:
Pastures:
Grazers are main problem


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As long as only the upper half of the
grass blade is eaten then grass is a
renewable resource
Overgrazing:
Undergrazing:
Managing and Sustaining
Grasslands

Solutions:

Control the number of grazing animals and the
duration of their grazing in a given area.


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Rotational grazing:
Suppress the growth of unwanted invader plants
Replanting native seeds to barren areas can
restore rangelands but can be expensive
National Parks


There are more then 1,100 national
parks larger then 4 sq miles located in
120 countries
Only 1% of Parks in developing
countries are actually protected.