Photo of spotted salamander.
Photo credit: Matt Perry

<< Back   Next >>
Many animals need wetlands for part or all of their life-cycles. In late winter and early spring, for example, adult tiger salamanders migrate from uplands to vernal pools for breeding and egg deposition. The gilled larvae resulting from their fertilized eggs then develop further, eventually producing lungs. Therefore, they must leave the vernal pools for adjacent upland, generally forested, habitat as adults, where they are mainly subterranean. In this instance, a complex of wetlands within a forest matrix is important as the life-cycle requirements of the tiger salamanders change. Thus, for the existence of the tiger salamander, both wetlands and uplands are important and essential. This can similarly be said of other amphibians like the spotted salamander as well as many other animals.

The diversity of habitats in a watershed or larger landscape unit is also important for other ecological functions associated with wetlands. One such function, biogeochemical cycling, involves the biologic, physical, and chemical transformations of various nutrients within the biota, soils, water, and air. Wetlands are very important in this regard, particularly relating to nitrogen, sulfur, and phosphorous. A good example of this occurs in anaerobic (non-oxygenated) and chemically reduced wetland soils and the muddy sediments of aquatic habitats like estuaries, lakes, and streams, which support microbes that function in nitrogen and sulfur cycling. Upon death and decay, the nitrogen and sulfur in plant and animal biomass is released through mineralization. Much of this is eventually transformed into gaseous forms and released into the atmosphere, where it once again becomes available to certain plants and their associated nitrogen-fixing bacteria in the soil. This is literally a major defense for mud, since it is the anaerobic and chemically reducing conditions in the substrate, in conjunction with various microbes, that ensure the gaseous release of the nitrogen and sulfur. On the other hand, phosphorous does not have a gaseous form, but vascular plants in wetlands transform inorganic forms of phosphorus (that might otherwise be shunted into undesirable algal blooms) into organic forms in their biomass as they grow. Thus, wetlands provide the conditions needed for the removal of both nitrogen and phosphorus from surface water.

Scientists also point out that atmospheric maintenance is an additional wetland function. Wetlands store carbon within their live and preserved (peat) plant biomass instead of releasing it to the atmosphere as carbon dioxide, a greenhouse gas affecting global climates. Therefore, wetlands world-wide help to moderate global climatic conditions. On the other hand, filling, clearing and draining wetlands releases carbon dioxide.

Wetlands also play an important role in the hydrologic cycle -- a cycle we all experience quite readily, for example, with the precipitation from a thunderstorm and the evaporation of ponded water from a puddle or bird bath. Wetlands can receive, store, and release water in various ways -- physically through ground water and surface water, as well as biologically through transpiration by vegetation -- and therefore function in this very important global cycle.

Some specific examples of the benefits of wetlands to society are elaborated below. In addition, since wetlands play an integral role in the ecology of watersheds, the Watershed Academy Web module on Watershed Ecology is very pertinent. These additional modules will be very helpful in understanding the ecology of watersheds and the role of wetlands in a watershed context.

<< Back   Next >>

Section 3 of 12