Deforestation: A Global Dilemma

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