Forestry

MANAGING AND SUSTAINING FORESTS

Forests provide a number of ecological and economic services that researchers have attempted to estimate their total monetary value.

Figure 10-4Figure 10-4

Global Outlook: Extent of Deforestation

Human activities have reduced the earth’s forest cover by as much as half.

Losses are concentrated in developing countries.

Figure 10-7Figure 10-7

Case Study: Deforestation and the Fuelwood Crisis

Almost half the people in the developing world face a shortage of fuelwood and charcoal.In Haiti, 98% of country is deforested.MIT scientist has found a way to make charcoal from

spent sugarcane.

Harvesting Trees

Building roads into previously inaccessible forests paves the way for fragmentation, destruction, and degradation.

Figure 10-8Figure 10-8

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 10-9Figure 10-9

Harvesting Trees

Effects of clear-cutting in the state of Effects of clear-cutting in the state of Washington, U.S.Washington, U.S.

Figures 10-10 and 10-11Figures 10-10 and 10-11

SolutionsWe can use forests more sustainably by

emphasizing:Economic value of ecological services.Harvesting trees no faster than they are

replenished.Protecting old-growth and vulnerable areas.

Figure 10-12Figure 10-12

CASE STUDY: FOREST RESOURCES AND

MANAGEMENT IN THE U.S.U.S. forests cover more area than in 1920.Since the 1960’s, an increasing area of old growth

and diverse second-growth forests have been clear-cut.Often replace with tree farms.Decreases biodiversity.Disrupts ecosystem processes.

Types and Effects of Forest Fires

Depending on their intensity, fires can benefit or harm forests.Burn away flammable ground material.Release valuable mineral nutrients.

Figure 10-13Figure 10-13

Types of Fires

• Surface fires – burn only undergrowth and leaf litter– Reduces chances of more destructive fires– Help recycle minerals– Release seeds for germination

Types of Fires

• Crown fires – start on the ground but eventually burn whole trees– Rapidly burning fires– Occur when there is a large build up of

litter– Destroy vegetation– Kill wildlife– Increase soil erosion– Stop when they run out

of fuel

Types of fires• Ground fires – surface fires that go underground

and burn decaying leaves and peat– May smolder for days or weeks– Difficult to detect and extinguish– consumes all or most of the organic cover, and

exposes mineral soil or underlying rock– Usually occur during drought

Prescribed Burns• intentional ignition of grass, shrub, or forest

fuels for specific purposes according to predetermined conditions.– Expose mineral soil for seedbeds for regeneration

of wind-disseminated species – Control of insects, diseases, and competing

vegetation – Fuel reduction

Solutions: Controversy Over Fire ManagementIn 2003, U.S. Congress passed the Healthy Forest

Restoration Act:• The primary goal of this Act is to reduce fire danger. • Allows timber companies to cut medium and large

trees in 71% of the national forests.• In return, must clear away smaller, more fire-prone

trees and underbrush.• Some forest scientists believe this could increase

severe fires by removing fire resistant trees and leaving highly flammable slash.

Solutions: Reducing Demand for

Harvest TreesTree harvesting can be

reduced by wasting less wood and making paper and charcoal fuel from fibers that do not come from trees.Ex )Kenaf - paper

production.

CASE STUDY: TROPICAL DEFORESTATION

Large areas of ecologically and economically important tropical forests are being cleared and degraded at a fast rate.

Figure 10-16Figure 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 10-17Figure 10-17

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 10-18Figure 10-18

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 10-10AFigure 10-10A

NATIONAL PARKSCountries have established more than 1,100

national parks, but most are threatened by human activities.Local people invade park for wood, cropland, and

other natural resources.Loggers, miners, and wildlife poachers also deplete

natural resources.Many are too small to sustain large-animal species.Many suffer from invasive species.

Case Study: Stresses on U.S. National Parks

Overused due to popularity.

Inholdings (private ownership) within parks threaten natural resources.

Air pollution.

Figure 10-23Figure 10-23

Wilderness Act of 1964

• Provides for permanent protection of undeveloped and unexploited areas so that natural ecological processes can operate freely.

• 5% of land area in U.S.• Preservation, not conservation.• Limits recreational and commercial use

Forests and Rangeland Renewable Resources Research Act, 1978• Also known as the National Forest

Management Act• Authorizes the Secretary of Agriculture to

conduct renewable resources research activities on national forest and rangelands, including research relating to fish and wildlife and their habitats.

• Encourages multiple-use and sustained yield management of our national forests and rangeland.

• Lands managed by the U.S. federal government.

• U.S. citizens jointly own these and other public lands.

Figure 25-9Figure 25-9

NATURE RESERVES

Ecologists call for protecting more land to help sustain biodiversity, but powerful economic and political interests oppose doing this.Currently 12% of earth’s land area is protected.Only 5% is strictly protected from harmful human

activities.Conservation biologists call for full protection of

at least 20% of earth’s land area representing multiple examples of all biomes.

NATURE RESERVESLarge and medium-sized reserves with buffer

zones help protect biodiversity and can be connected by corridors.

Costa Rica has consolidated its parks and reserves into 8 megareserves designed to sustain 80% if its biodiversity.

Figure 10-10BFigure 10-10B

NATURE RESERVES

We can prevent or slow down losses of biodiversity by concentrating efforts on protecting global hot spots where significant biodiversity is under immediate threat.

Conservation biologists are helping people in communities find ways to sustain local biodiversity while providing local economic income.

34 hotspots identified by ecologists as important and endangered centers of biodiversity.

Figure 10-26Figure 10-26

NATURE RESERVES

Wilderness is land legally set aside in a large enough area to prevent or minimize harm from human activities.

Only a small percentage of the land area of the United States has been protected as wilderness.

ECOLOGICAL RESTORATION

Restoration: trying to return to a condition as similar as possible to original state.

Rehabilitation: attempting to turn a degraded ecosystem back to being functional.

Replacement: replacing a degraded ecosystem with another type of ecosystem.

Creating artificial ecosystems: such as artificial wetlands for flood reduction and sewage treatment.

ECOLOGICAL RESTORATION

Five basic science-based principles for ecological restoration:Identify cause.Stop abuse by eliminating or sharply reducing

factors.Reintroduce species if necessary.Protect area form further degradation.Use adaptive management to monitor efforts,

assess successes, and modify strategies.