Chapter 6: Environmental Conservation: Forests, Grasslands, Parks, and Nature Preserves

savannas

An open prairie or grassland with scattered groves of trees.

closed-canopy forests

A forest where tree crowns spread over 20 percent of the ground; has the potential for commercial timber harvests.

old-growth forests

Forests free from disturbance for long enough (generally 150-200 years) to have mature trees, physical conditions, species diversity, and other characteristics of equilibrium ecosystems.

monoculture forestry

Intensive planting of a single species; an efficient wood production approach, but one that encourages pests and disease infestations and conflicts with wildlife habitat or recreation uses.

deforestation

Removing trees from a forest.

clear-cutting

Cutting every tree in a given area, regardless of species or size; an appropriate harvest method for some species; can be destructive if not carefully controlled.

shelterwood harvesting

Mature trees are removed from the forest in a series of two or more cuts, leaving young trees and some mature trees as a seed source for future generations.

strip-cutting

Harvesting trees in strips narrow enough to minimize edge effects and to allow natural regeneration of the forest.

selective cutting

Harvesting only mature trees of certain species and size; usually more expensive than clear-cutting but less disruptive for wildlife and often better for forest regeneration.

ecosystem management

An integration of ecological, economic, and social goals in an unified systems approach to resource management.

pastoralists

People who live by herding domestic animals.

desertification

Denuding and degrading a once fertile land, initiating a desert-producing cycle that feeds on itself and causes long-term changes in soil, climate, and biota of an area.

overgrazing

Allowing domestic livestock to eat so much plant material that it degrades the biological community.

rotational grazing

Confining grazing animals in a small area for a short time to force them to eat weedy species as well as the more desirable grasses and forbes.

world conservation strategy

A proposal for maintaining essential ecological processes, preserving genetic diversity, and ensuring that utilization of species and ecosystems is sustainable.

ecotourism

A combination of adventure travel, cultural exploration, and nature appreciation in wild settings.

Man and Biosphere (MAB) program

A design for nature preserves that divides protected areas into zones with different purposes. A highly protected core is surrounded by a buffer zone and peripheral regions in which multiple-use resource harvesting is permitted.

biosphere reserves

World heritage sites identified by the IUCN as worthy for national park or wildlife refuge status because of high biological diversity or unique ecological features.

corridors

Strips of natural habitat that connect two adjacent nature preserves to allow migration of organisms from one place to another.

core habitat

A habitat patch large enough and with ecological characteristics suitable to support a critical mass of the species that make up a particular community.

edge effects

A change in species composition, physical conditions, or other ecological factors at the boundary between two ecosystems.