Chapter Summary

Major ecosystem types called biomes are characterized by similar climates, soil conditions, and biological communities. Among the major terrestrial biomes are deserts, tundra, grasslands, temperate deciduous forests, temperate coniferous forests, tropical moist forests, and tropical seasonal forests. Aquatic ecosystems include oceans and seas, rivers and lakes, estuaries, marshes, swamps, bogs, fens, and reefs. Moisture and temperature are generally the most critical determinants for terrestrial biomes. Periodic natural disturbances, such as fires, play a major role in maintaining some biomes.

Humans have disturbed, preempted, or damaged much—perhaps half or more—of all terrestrial biomes and now dominate about 40 percent of all net primary productivity on the land. Some of this disturbance and domination is permanent, but we have opportunities to apply ecological knowledge and practical experience to restoring and repairing ecosystems. In some cases, all we have to do is leave nature alone; in other cases, more active management is required to reestablish functioning ecosystems. Remediation usually means cleaning the soil of pollution, while reclamation is applied to physical repair of severely damaged land. Mitigation means to replace or re-create an ecosystem in restitution for damage caused by a construction project or some other human activity. Whether we can or should try to create new, synthetic forms of nature is controversial.

Landscape ecology is the study of reciprocal effects of spatial pattern on ecological processes. A landscape, in this sense, is a bounded geographical unit that includes both living and nonliving components. History is important in that it shapes the land and organisms as well as our reactions to, and interpretations of, the landscape. Humans are important elements of most landscapes and few places on the earth are devoid of human impacts. Restricting our definition of “nature” to a few pristine remnants will lead us either to ignore most of the earth’s surface or to demand that humans remove themselves entirely from large tracts, something not very likely.

Patchiness and heterogeneity are characteristic of most landscapes. Movement of organisms and materials across boundaries between habitat patches play an important regulatory role in many ecosystems. Some landscape patterns apply across a wide range of scales, while others are restricted to a specific scale.

Ecosystem management involves managing whole landscapes over long time scales, taking human needs into consideration, maintaining biodiversity and ecological processes, utilizing innovative institutional arrangements, integrating science and policy, encouraging public involvement, and adapting management based on conscious experimentation and routine monitoring. Ecosystem management, like sustainable development, recognizes that social goals, environmental quality, and economic health are all inextricably interlinked.