Saturday, May 5, 2012

Watersheds and Ecology

A watershed is an area of land surrounding a riparian habitat that supplies all of the habitat’s water. Environmental damage to a watershed in the form of pollution or erosion directly affects its riparian waters. Conversely, a healthy environment and watershed give rise to healthy riparian habitat. For instance, undisturbed watersheds containing trees and plant life have riparian areas with clean, clear water. Vegetation, ground cover, and extensive root systems in these places prevent sediments and runoff. In heavy rainstorms, water rushes into streams and dirties the water with soil. A slow leaching of soils and vegetation, by contrast, adds nutrients to the riparian system rather than polluting it.

Clean inflow from healthy watersheds replenishes riparian habitat for a diverse collection of microbial, plant, and animal life. The banks and sediments of streams contain bacteria and fungi that decompose organic matter in the water and soil. Life on the water’s bottom, on rocks and pebbles, is usually composed of microbial communities called biofilms, made up of bacteria and algae, and small plant life called phytoplankton. Invertebrates and dissolved minerals in riparian water feed insect larvae and small fish, and many riparian habitats contain freshwater fish upon which large and small mammals prey. Riparian sites also provide shelter for animals, migration routes, and a shady resting place in hot climates.

Riparian vegetation prefers moist, shady conditions; some species contain root systems that have adapted to a shallow water table and tolerate seasonal flooding. The deep roots of riparian trees prevent erosion and the undercutting of banks in which flowing water wears the bank away from the bottom up. Native plants along waterways provide shelter for insects, amphibians, reptiles, mammals, and birds. Vegetation that overhangs flowing waters also helps keep the waters cool for fish such as trout and salmon, which are discussed in the sidebar “Salmon.”

Source of Information : Green Technology Conservation Protecting Our Plant Resources

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