Chapter 23: Sustaining Terrestrial Biodiversity

How is Land Used?No nation has set aside as much land– about 42%--for public use, resource extraction, enjoyment and wildlife as the United States.

Rangeland and pasture 29%

Major types of U.S. Public LandsMultiple Use Lands

• National Forest System—used for logging, mining, livestock grazing, farming, oil and gas extraction, recreation, sport hunting, fishing, and conservation. Moderately Restricted-Use Lands

• National Wildlife Refuges—protest habitats and breeding areas for waterfowl and big game, provide game for hunting. Some activities from above permitted on a limited bases.

Restricted-Use Lands• National Park System—camping,

hiking, sport fishing, and boating.

How should public land be managed?

Most conservation biologists believe the following should be followed:

• Protect biodiversity and wildlife habitats

• No tax breaks for extracting resources

• Public get fair compensation for use of their property

• Users be responsible for environmental damage.

Managing ForestEconomic Important of Forests

• Fuel wood (50% of global use)• Industrial timber and lumber• Pulp and paper• Medicines• Mineral extraction and

recreation

Managing ForestsTypes of Forest:

• Old-growth (virgin) forest—have not been seriously disturbed by human activities for a least several hundred years.

• Second-growth forest –stands of trees resulting from secondary succession

• Tree plantations—tree farms: managed tracts of uniformly aged trees of one species.

Forest Structure

Layers of Biodiversity in a Douglas Fir.

Types of Forest ManagementEven-aged Management—

also called industrial forestry and tree plantation replaces a diverse forest with one or two fast-growing species that can be harvested every 6-100 years.

Uneven-aged Management—maintaining a variety of tree species. Harvested by selective cutting of individual trees.

How are Trees harvested?The first step in forest management is to build roads for access. Even with careful design, logging roads have a number of harmful effects.

• Increased erosion• Habitat fragmentation• Pathways for exotic species• Accessibility for humans

Selective Cutting

Intermediate-aged or mature trees are cut singly in an uneven-aged forest.

Shelterwood CuttingRemoves all mature trees in two or three cuttings over a period of about 10 years.

Seed-tree CuttingHarvest nearly all trees in one cutting, leaving a few seed-producing trees to regenerate the stand.

Clear CuttingRemove all trees from an area in a single cutting.

Strip CuttingA variation of clear cutting—cutting a strip of trees narrow enough to allow natural regeneration. Then cutting other strips over several decades.

Sustainable Forestry• Longer rotations between cuttings• Selective or strip cutting• Minimize fragmentation• Improve road building techniques• Certify trees sustainably grown

Forest Pathogens Insect Pests

• Bark beetles—bore channels through layer beneath the bark of conifers

• Spruce budworm and gypsy moth larvae—introduced from Europe—kill trees by consuming foliage needed for photosynthesis.

• Hemlock woolly adelgid—introduced from Asia, now controlled by a beetle from Japan. Feeds by sucking sap from hemlock trees.

Parasitic Fungi• Chestnut blight—introduced

from China—killed almost all American chestnut trees. Until the early 1950s , the largest most impressive tree in the eastern United States forest was the American chestnut.

• Dutch Elm disease—from Asia by way of Europe.

• White pine blister rust—from Europe

Affects of FiresFires are important to maintain certain ecosystems:

• Savanna• Temperate grasslands• Chaparral• Southern pine forest• Sequoia trees

Types of FiresSurface Fires—burn only undergrowth, occasional surface fires stimulate the germination of certain tree seeds and help maintain the habitat.

Crown Fires—may start on the ground but eventually burn whole trees. Usually occur in area that have had no surface fires for decades. These fires destroy most vegetation, kill wildlife, and increase soil erosion.

Fig. 23-17 p. 607

Forest Resources:• Habitat for threatened and

endangered species• Water purification• Recreation• Timber harvest

Tropical Deforestation• Rapid and increasing• Loss of biodiversity• Cultural extinction• Unsustainable

agriculture and ranching

• Commercial logging• Fuel wood

Reducing Tropical Deforestation• Identification of critical ecosystems• Reducing poverty and population growth• Sustainable tropical agriculture• Protection of large tracts of land• Less destructive timber harvesting methods

National ParksWorldwide about 1100 national parks larger than 10 sq. km. (4 sq. miles).The U. S. national park system, established in 1912 has 55 national parks, most of them in the west.

Problems Managing National Parks• Most are too small to maintain biodiversity• Invasion by exotic species• Too popular—too many visitors, traffic jams,

noise, and air pollution

Social principles useful in establishing, managing, and protecting reserves:

• Include local people in the planning and design

• Create user-friendly reserves that allow local people to use a surrounding buffer-zone for sustainable timber cutting, livestock grazing, hunting, and fishing.

Areas of Top PriorityPrevention strategy—designed to reduce the future loss of biodiversity. Establishing a variety of reserves in the world’s most biodiverse countries.Emergency action—identifies and quickly protects biodiversity hot spots—Areas especially rich in plant and animal species that are found nowhere else in great danger of extinction.

Ecological RestorationRehabilitation—any attempt to restore at least some of a degraded system’s natural species and ecosystem functions. Such as removing pollutants and replanting areas.Replacement—replacing a degraded ecosystem with another type of ecosystem. Such as replacing a degraded forest with a pasture or tree plantation.Creating artificial ecosystems