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| Broad, regional types of ecosystems characterized by distinctive climate and soil conditions and distinctive kinds of biological community adapted to those conditions. |
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| The number and variety of species. |
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| A term applied to vegetation zones defined by altitude. |
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| High mountain forests where temperatures are uniformly cool and fog or mist keeps vegetation wet all the time. |
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| Forests near the equator in which rainfall is abundant--more than 200 cm (80 in.) per year--and temperatures are warm to hot year-round. |
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| Tropical Seasonal Forests |
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| Semi-evergreen or partly deciduous forests tending toward open woodlands and grassy savannas dotted with scattered, drought-resistant trees. |
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| Biomes dominated by grasses and associated herbaceous plants. |
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| An open prairie or grassland with scattered groves of trees. |
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| Biomes characterized by low moisture levels and infrequent and unpredictable precipitation. Daily and seasonal temperatures fluctuate widely. |
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| A biological community characterized by thick growth of thorny, evergreen shrubs typical of a Mediterranean climate. |
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| Trees and shrubs that shed their leaves at the end of the growing season. |
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| A broad band of mixed coniferous and deciduous trees that stretches across northern North America (and Europe and Asia); its northernmost edge, the taiga, intergrades with the arctic tundra. |
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| Treeless arctic or alpine biome characterized by cold, dark winters; a short growing season; and potential for frost any month of the year; vegetation includes low-growing perennial plants, mosses, and lichens. |
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| Microscopic, free-floating, autotrophic organisms that function as producers in aquatic ecosystems. |
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| The bottom of a sea or lake. |
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| Zones in the vertical water column of a water body. |
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| Prominent oceanic features composed of hard, limy skeletons produced by coral animals; usually formed along edges of shallow, submerged ocean banks or along shelves in warm, shallow, tropical seas. |
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| Whitening of corals when stressors, such as high temperatures, induce corals to expel their colorful single-celled protozoa, known as zooxanthellae, or when zooxanthellae die. Death of the coral reef may result. |
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| Large expanses of rooted, submerged, or emergant aquatic vegetation, such as eel grass or salt grass. |
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| Diverse groups of salt-tolerant trees and other plants that grow in intertidal zones of tropical coastlines. |
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| Bays or drowned valleys where a river empties into the sea. |
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| A wetland with salt water and salt tolerant plants, usually coastal. |
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| Small pools of water left behind by falling tides. |
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| In water, a distinctive temperature transition zone that separates an upper layer that is mixed by the wind (the epilimnion) and colder deep layer that is not mixed (the hypolimnion). |
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| Wetlands with trees, such as the extensive swamp forests of the southern United States. |
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| Wetlands without trees; in North America, this type of land is characterized by cattails and rushes. |
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| Areas of waterlogged soil that tend to be peaty; fed mainly by precipitation; low productivity; some bogs are acidic. |
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| Wetlands fed mainly by ground water. |
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| The genetic, species, and ecological diversity of the organisms in a given area. |
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| Phylogenetic Species Concept |
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| A definition of species that depends on genetic similarities (or differences). |
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| Evolutionary Species Concept |
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| A definition of species that depends on evolutionary relationships. |
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| The irrevocable elimination of species; can be a normal process of the natural world as species out compete or kill off others or as environmental conditions change. |
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Habitat destruction
Invasive species
Pollution
Population of humans
Over-harvesting |
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| Disruption of habitat into small, isolated fragments. |
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| Minimum Viable Population |
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| The number of individuals needed for long-term survival of rare and endangered species. |
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| The study of rates colonization and extinction of species on islands or other isolated areas based on size, shape, and distance from other inhabited regions. |
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| Organisms that thrive in new territory where they are free of predators, diseases, or resource limitations that may have controlled their population in their native habitat. |
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| Locating or studying organisms at a distance using radio signals or other electronic media. |
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| Harvesting so much of a resource that it threatens its existence. |
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| A species considered to be in imminent danger of extinction. |
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| While still abundant in parts of its territorial range, this species has declined significantly in total numbers and may be on the verge of extinction in certain regions or localities. |
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| Naturally rare organisms or species whose numbers have been so reduced by human activities that they are susceptible to actions that could push them into threatened or endangered status. |
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