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Chapter 6: Environmental Conservation: Forests, Grasslands,

Parks, and Nature Preserves

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Chapter Six Topics

• World Forests

• Rangelands

• Parks and Nature Preserves

• World Parks and Preserves

• Wilderness Areas

• Wildlife Refuges

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Main vegetation zones of the world's forests under natural conditions

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Part 1: World Forests

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Forest Products

firewood rubber

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Wood Consumption• Total annual world wood consumption is

about 3.7 billion metric tons, more than steel and plastic consumption together.

• Firewood accounts for slightly more than 50% of all wood harvested worldwide.

• Developed countries produce less than half of all industrial wood, but account for about 80% of its consumption.

• By 2025, demand for fuelwood may be twice the available supply.

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• About 25% of the world's forests are managed for wood production.– Extraction– Replanting – scientific planning for sustainable harvests

• Monoculture forestry - single species replanted

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Some Causes of Tropical Deforestation

• Logging for valuable hardwoods such as mahogany, teak, ebony– Taking down one tree often brings down several

others– Building roads opens forest to others

• Clearing of land for cattle ranches and export crop production (bananas, pineapples, etc.)

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Cutting and burning of tropical rainforest results in

• Wildlife destruction;

• Habitat loss;• Rapid water

runoff;• Soil erosion;

and• Waste of forest

resources.

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One model

• Cutting down forest reduces plant transpiration• Rainfall decreases• Drought kills more vegetation, fires increase,

further destroying remaining forest

National forests

• Originally set aside for development of their natural resources (that is, the trees)

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Temperate Forest Issues

• Logging of old-growth

• Endangered species vs. jobs

• Northern spotted owl

• Salmon

Old-growth forests

• Many of large trees >1000 yrs old

• e.g., Pacific Northwest

• High biodiversity, large amounts of biomass accumulate

• In U.S., <10% remain, 80% of this to be cut

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Clear-cutting and Road Building

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Fire Management Issues

Fire suppression vs. natural burnout

• Since 1930’s, policy is to suppress natural fires– Results in buildup of dead material– Especially bad in dry areas

• Many natural communities adapted to periodic fires; fires needed for regeneration

• Controlled burns

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Grassland – a biome dominated by grasses and other herbaceous plants

Rangeland – grasslands (and open forest) that are suitable for livestock grazing

Part 2: Rangelands

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Overgrazing

Overgrazed Rangeland

Lightly grazedpasture

(cattle) (native grazers)

• Rain runs off before it can soak into ground; springs & wells dry up

• Seeds unable to germinate• Barren ground reflects more of sun’s heat,

changing wind patterns, driving away rain clouds

• Further desiccation• Converts fertile land to desert -

desertification

Effects of overgrazing

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New Approaches to Ranching

• Using short-duration, rotational grazing• Raising wild native species, such as bison

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Part 3:Parks andNature Preserves

Parks worldwide

• More parks in North & South America than in rest of world

• In parks in N. Am., land actually set aside• In U.S., areas originally set aside as wilderness

areas (more on these later)• In other areas of the world, parks of have people

living in them, or have plantations rather than native forest

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U.S. National Park System

• 376 parks, monuments, historic sites, and recreation areas

• Total size: 108,000 square miles

• 300 million visitors each year

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Park Problems

• Development pressures at boundaries• Overcrowding and visitor demands for facilities• Pollution, noise, and environmental

degradation due to motorized vehicles• Mining and oil interests (and others)

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Wildlife Issues

• Reintroduction of predators

• Hunting• Increased human/ animal

interaction

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Parks as Ecosystems• Park boundaries

usually based on political rather than ecological considerations

• Biogeographical area important

• IUCN categories (International Union for Conservation of Natural Resources)

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Size and Design of

Nature Preserves • SLOSS debate - is it

better to have single large or several small reserves?

• Edge effects• Corridors of natural

habitat essential

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Experiment in Brazilian rainforest. Scientists tracking wildlife in different sized plots, some connected to others, some surrounded by clearcuts.

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Conservation and Economic Development

• Immediate human survival always takes precedence over long-term environmental goals.

• Ecotourism - a viable option ?

• Indigenous peoples

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Part 5: Wilderness Areas

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Wilderness area o 1964 Wilderness Acto More protection than in a National Parko Made of undeveloped land affected primarily by natural forces; humans are merely visitorso Most areas in the western states and Alaskao Designation as a wilderness may actually degrade the area

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Do we need more wilderness?

• For: refuge for endangered wildlife, opportunity for solitude and primitive recreation, baseline for ecological research, contains features of geological, scientific, or historical value

• Against: natural resources locked up, decreased access for motorized recreation, traditional ways of life threatened

• For many people, especially those in developing countries, the idea of having pristine wilderness is not very important.

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Part 6: Wildlife Refuges • Areas to preserve wildlife habitat in U.S.

• Approximately 1% of U.S. surface area (511 total)

• About 60% of all refuges allow activities that are harmful to wildlife.

• More than 75% of U.S. refuges have water pollution problems.

Refuges in developing countries

• Preserves set up mainly to protect wildlife

• Example: Serengeti system in Kenya & Tanzania– Wildebeests, zebras, gazelles, impalas,

giraffes, lions, leopards, hyenas, cheetas, wild dogs, vultures, to name a few

• Major problem – poaching– Illegal hunters massacre wildlife for meat,

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