Ecology Terms Starting With W
Ecology Glossary: W
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Watershed
/ WAW-ter-shed / · Old English waeter (water) + Old English sceadan (to divide)
Watershed watershed is the entire area of land that drains water to a common outlet such as a river, lake, estuary, or wetland.
Watershed boundaries are defined by topographic divides that determine which direction precipitation flows; water, sediment, nutrients, and pollutants from the entire watershed ultimately reach the outlet stream or lake. Managing a watershed integrates land use practices with water quality and quantity goals; deforestation, impervious surface creation, and agricultural nutrient inputs all affect downstream water quality within the watershed. The Hubbard Brook watershed experiments demonstrated that intact forested watersheds retain virtually all nutrient inputs and regulate streamflow with minimal flood peaks.
A watershed is all the land that drains to a common body of water. Activities far upstream can affect water quality downstream.
A watershed is only the river channel. It includes surrounding land, slopes, soils, streams, and human land uses that drain into the water.
Fertilizer applied on farms in a watershed can wash into streams after rain. Those streams may carry nutrients to lakes or estuaries.
Wetland
/ WET-land / · Old English waet (wet) + land
Wetland wetland is an ecosystem where water at or near the soil surface for much of the year shapes the soil, vegetation, and animal communities.
Wetlands occur at the interface of aquatic and terrestrial ecosystems and are among the most ecologically productive and biodiverse habitats on Earth. Coastal wetlands, including salt marshes and mangroves, buffer storm surge, trap sediment, and provide nursery habitat for fish and invertebrates. Inland wetlands store floodwater, filter nutrients, and support amphibians, birds, insects, and aquatic plants.
Wetlands are shaped by water at or near the soil surface for much of the year. They can store water, filter pollutants, and provide habitat.
Wetlands are wastelands that should be drained. Wetlands are highly valuable ecosystems for wildlife, flood control, and water quality.
A marsh wetland supports cattails, frogs, dragonflies, ducks, microbes, and fish nurseries. Waterlogged soils influence which plants can grow.
Wildlife Corridor
/ WYLD-lyf KOR-ih-dor / · Old English wilde (wild) + lif (life) + Latin corridore (passage)
Wildlife Corridor is a strip or network of habitat connecting isolated patches of natural or semi-natural land.
Effective wildlife corridors match the movement requirements of the species they are designed to serve. Large mammals often require wide corridors with cover, low road density, and enough habitat to move safely between protected areas. Corridors benefit species by reducing extinction risk in individual fragments, facilitating post-disturbance recolonization, maintaining genetic diversity through gene flow, and enabling range shifts in response to climate change.
Wildlife corridors connect habitat patches so animals can move between them. They can support migration, gene flow, and recolonization.
A corridor must be a perfect strip of untouched wilderness. Useful corridors can include river edges, hedgerows, overpasses, or restored habitat links.
A forested corridor between two reserves can help monkeys or deer move safely. This movement reduces isolation of the populations.
Wildlife Trade
/ WYLD-lyf TRAYD / · Old English wilde (untamed) + lif (life) + Middle Low German trade (track, course)
Wildlife trade is the buying and selling of wild organisms. It covers live animals, plants, and products made from them. Products include meat, skins, ivory, timber, and medicines. Trade can be legal and regulated, or illegal. International trade in listed species is regulated by CITES. Overharvesting for trade threatens many species with extinction.
CITES was signed in Washington on 3 March 1973. It entered into force on 1 July 1975. By 2025 it had 185 parties covering over 40,900 taxa.
Appendix I bans commercial trade in wild-caught specimens. Appendix II allows trade under export permits. Appendix III lists species protected by at least one country.
Trade also moves diseases between species and continents. Wildlife markets can spread zoonoses to people. Escaped pets can become introduced species.
The Helmeted Hornbill (Rhinoplax vigil) carries a nearly solid casque. This casque can make up 10 percent of its weight. Carvers prize it as red ivory. A 2013 Indonesian study found 6,000 killed in a year.
Many people assume most wildlife trade is illegal. In fact, most CITES-listed species are in Appendix II. Their trade is legal when permits show it is sustainable. Illegal trade is still a serious threat for many species.
The African Grey Parrot (Psittacus erithacus) is a prized pet. Trappers took over 1.5 million wild birds in 25 years. It has vanished from much of its West African range. In October 2016, CITES moved it to Appendix I.
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