Deforestation: A Global Dilemma
Deforestation is estimated to have increased erosion and caused the loss of 562 million hectares of soil.
Deforestation in one country can affects countries downstream– E.g. Nepal and India
Deforestation: A Global Dilemma
Is forested area increasing or decreasing?– Information is lacking on which to
base an accurate evaluation– Forest cover is large, often remote– Difficult to assess the total amount
of forest area– Estimates suggest an annual loss
each year of 7.3 million hectares
Causes of Deforestation Two most common reasons
– Clear land for agriculture and settlement
– To use to sell timber for lumber, paper products, or fuel
Indirect Deforestation The death of trees from pollution
or disease– Acid rain– Ozone– Other air pollutants– All can increase susceptibility to
disease Global climate change may lead
to– Major die-off and shift in areas of
potential growth
Fig. 10-7, p. 196
• 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 migratoryspecies such as birds and butterflies
• Regional climate change from extensive clearing
• Release of CO2 into atmosphere
• Acceleration of flooding
Natural Capital Degradation
Deforestation
CASE STUDY: TROPICAL DEFORESTATION
Large areas of ecologically and economically important tropical forests are being cleared and degraded at a fast rate. Figure 10-16
CASE STUDY: TROPICAL DEFORESTATION
At least half of the world’s terrestrial plant and animal species live in tropical rain forests.
Large areas of tropical forest are burned to make way for cattle ranches and crops.
Figure 10-17
Solutions: Reducing Demand for Harvest Trees
Tree harvesting can be reduced by wasting less wood and making paper and charcoal fuel from fibers that do not come from trees.– Kenaf is a
promising plant for paper production.
Figure 10-15
Why Should We Care about the Loss of Tropical Forests?
About 2,100 of the 3,000 plants identified by the National Cancer Institute as sources of cancer-fighting chemicals come from tropical forests.Figure 10-18
Why Should We Care about the Loss of Tropical Forests?
About 2,100 of the 3,000 plants identified by the National Cancer Institute as sources of cancer-fighting chemicals come from tropical forests.Figure 10-18
Fig. 10-18a, p. 205
Rauvolfia Rauvolfia sepentina, Southeast AsiaTranquilizer, high blood pressure medication
Fig. 10-18b, p. 205
Foxglove Digitalis purpurea, EuropeDigitalis for heart failure
Fig. 10-18c, p. 205
Pacific yew Taxus brevifolia, Pacific NorthwestOvarian cancer
Fig. 10-18d, p. 205
CinchonaCinchona ledogeriana, South AmericaQuinine for malaria treatment
Fig. 10-18e, p. 205
Rosy periwinkle Cathranthus roseus, MadagascarHodgkin's disease, lymphocytic leukemia
Fig. 10-18f, p. 205
Neem tree Azadirachta indica, IndiaTreatment of many diseases, insecticide, spermicide
Fig. 10-20, p. 207
Protect most diverse and endangered areas
Educate settlers about sustainable agriculture and forestry
Phase out subsidies that encourage unsustainable forest use
Add subsidies that encourage sustainable forest use
Protect forests with debt-for-nature swaps and conservation easements
Certify sustainably grown timber
Reduce illegal cutting
Reduce poverty
Slow population growth
Restoration
Reforestation
Rehabilitation of degraded areas
Concentrate farming and ranching on already-cleared areas
Solutions
Sustaining Tropical Forests
Prevention
Kenya’s Green Belt Movement:
Individuals Matter Wangari Maathai
founded the Green Belt Movement.
The main goal is to organize poor women to plant (for fuelwood) and protect millions of trees.
In 2004, awarded Nobel peace prize. Figure 10-10A
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