major regional ecological community of plants and animals; usually corresponds to plant ecologists' and European ecologists' classification of plant formations and life zones.
of leaves, shed during a certain season (winter in temperate regions; dry season in the tropics); of trees, having deciduous parts.
applied to trees and shrubs for which there is no complete seasonal loss of leaves; two types, broadleaf and needle-leaf.
a narrow belt of tall grasses dominated by big bluestem that once ran north and south adjacent to the deciduous forest of eastern North America; presence maintained by fire; largely destroyed by cultivation.
grassland in mid North America, characterized by great variation in precipitation and a mixture of largely cool-season shortgrass and tallgrass species.
Westernmost grasslands of the Great Plains, characterized by infrequent rainfall, low humidity, and high winds; dominated by shallow-rooted, sod-forming grasses.
grassland of hot, dry climates, with rainfall varying between 200 and 500 mm, dominated by bunchgrasses and widely interspersed with other desert vegetation.
grassland in California dominated by exotic annual grassland that reseed every year, replacing native perennial grasses.
name given to Eurasian grasslands that extend from eastern Europe to western Siberia and China.
temperate South American grassland, dominated by bunchgrasses; much of the moister pampas are under cultivation.
extensive grasslands in the east of the interior of South Africa, largely confined to high terrain.
range of natural resources provided by ecosystems.
individuals or biomass removed or harvested from a population per unit time.
rotation period (or harvest interval)
interval between the recurrence of a disturbance event; or interval between harvests of a crop, such as trees.
yield per unit time equal to production per unit time in an exploited population.
processes by which environment produces such as air, water, timber, or fish.
planting of a single plant species.
planting of several plant species.
farming systems that alternate periods of annual cropping with extended fallow periods. also referred to as shifting cultivation; fire is used to clear fallow areas for cropping.
accelerated nutrient enrichment of aquatic ecosystems by a heavy influx of pollutants that cause major shifts in plant and animal life.
farming practices that provide a secure living for farm families while at the same time maintaining the natural environment and resources.
forest harvesting procedure in which all trees on the site are cut and removed.
seed-tree (or shelterwood) system
method of regenerating a new stand by removing all trees from an area except for a small number of seed-bearing trees.
method of forest harvesting in which only selected individual trees of high commercial value are removed from the forest stand.
mineralization of nutrients bound in organic compounds by fire.
maximum sustainable yield
the maximum rate at which individuals can be harvested from a population without reducing its size; recruitment balances harvesting.
an economic analysis in which the benefits of an activity are compared to the associated costs.
adding and comparing costs and benefits that occur at different times; a major driving force in the economics of resource management; often runs counter to the objectives of sustainable resource management.
when the actions of one individual or a group affect another individual's well-being, but relevant costs are not reflected in market prices.
study of environmental problems and the incorporation of economic principles into the environmental decision-making process.
having widespread geographic distribution.
restricted to a given region.
certain regions of the world exhibit both high species richness and endemism.
minimum viable population (MVP)
size of population that, with given probability, will ensure the population's existence for a stated period of time.
minimum dynamic area (MDA)
are of suitable habitat necessary for maintaining a minimum viable population.
applying principles of ecosystem development and function to the restoration and management of disturbed lands.
selective energy absorption by carbon dioxide in the atmosphere, which allows short wavelength energy to pass through but absorbs longer wavelengths and reflects heat back to Earth.
a gas that absorbs longwave radiation and thus contributes to the greenhouse effect when present in the atmosphere; includes water vapor, carbon dioxide, methane, nitrous oxides, and ozone.
the higher rates of diffusion and photosynthesis under elevated atmospheric concentrations of CO2.
general circulation models
help determine how increasing concentrations of greenhouse gases may influence large-scale patterns of global climate.