Wet meadow
A wet meadow is a semi-wetland meadow which is saturated with water throughout much of the year. Some experts consider a wet meadow to be a kind of marsh, while others consider it to be a distinct type of wetland[1]. Wet prairies and wet savannas are similar. Wet meadows may occur because of restricted drainage or the receipt of large amounts of water from rain or melted snow. They may also occur in riparian zones and around the shores of large lakes[2].
Unlike a marsh or swamp, a wet meadow does not have standing water present except for brief to moderate periods during the growing season. Instead, the ground in a wet meadow fluctuates between brief periods of flooding and longer periods of wetness. Wet meadows often have large numbers of wetland plant species, which frequently survive as buried seeds during dry periods, and then regenerate after flooding[3]. Wet meadows therefore do not usually support aquatic life such as fish. They typically have a high diversity of plant species, and may attract large numbers of birds, small mammals and insects including butterflies.
Vegetation in a wet meadow usually includes a wide variety of herbaceous species including sedges, rushes, grasses and a wide diversity of other plant species[4]. A few of many possible examples include species of Rhexia, Parnassia, Lobelia, many species of wild orchids (e.g. Calopogon and Spiranthes), and carnivorous plants such as Sarracenia and Drosera. Woody plants if present, account for a minority of the total area cover. High water levels are one of the important factors that prevent invasion by woody plants; in other cases, fire is important[5]. In areas with low frequencies of fire, or reduced water level fluctuations, or higher fertility, plant diversity will decline[6].
Wet meadows were once common in wetland types around the world[7][8]. They remain an important community type in wet savannas and flatwoods[9]. The also survive along rivers and lakeshores where water levels are allowed to change within and among years[10]. But their area has been dramatically reduced. In some areas, wet meadows are partially drained and farmed and therefore lack the biodiversity described here. In other cases, the construction of dams has interfered with the the natural fluctuation of water levels that generates wet meadows[11].
The most important factors in creating and maintaining wet meadows are therefore natural water level fluctuations and recurring fire. In some cases, small areas of wet meadow are artificially created. Due to the concern with damage that excessive stormwater runoff can cause to nearby lakes and streams, artificial wetlands can be created to capture stormwater[12]. Often this produce marshes, but in some cases wet meadows may be produced. The idea is to capture and store rainwater onsite and use it as a resource to grow attractive native plants that thrive in such conditions. The Buhr Park Children's Wet Meadow is one such project. It is a group of wet meadow ecosystems in Ann Arbor, Michigan designed as an educational opportunity for school-age children. In Europe, wet meadows are sometimes managed by hay-cutting and grazing[13].
References
- ^ Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p.
- ^ Wilcox, D.A, Thompson, T.A., Booth, R.K. and Nicholas, J.R. 2007. Lake-level variability and water availability in the Great Lakes. USGS Circular 1311. 25 p.
- ^ Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p.
- ^ Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p.
- ^ Peet, R. K. and Allard, D. J. (1993). Longleaf pine vegetation of the southern Atlantic and eastern Gulf Coast regions: a preliminary classification. In The Longleaf Pine Ecosystem: Ecology, Restoration and Management, ed. S. M. Hermann, pp. 45–81. Tallahassee, FL: Tall Timbers Research Station.
- ^ Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p.
- ^ Fraser, L. H. and Keddy, P. A. (eds.) 2005. The World’s Largest Wetlands: Ecology and Conservation. Cambridge, UK: Cambridge University Press.
- ^ Whigham, D.F., D. Dykyjova, and S. Hejny. 1993. Wetlands of the World, Vol. 1, Dordrecht, the Netherlands: Kluwer.
- ^ Peet, R. K. and Allard, D. J. (1993). Longleaf pine vegetation of the southern Atlantic and eastern Gulf Coast regions: a preliminary classification. In The Longleaf Pine Ecosystem: Ecology, Restoration and Management, ed. S. M. Hermann, pp. 45–81. Tallahassee, FL: Tall Timbers Research Station.
- ^ Keddy, P. A. and Fraser, L. H. (2002). The management of wetlands for biological diversity: four principles. In Modern Trends in Applied Aquatic Ecology, eds. R. S. Ambasht and N. K. Ambasht, pp. 21–42. New York: Kluwer.
- ^ Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p.
- ^ Hammer, D. A. (ed.) (1989). Constructed Wetlands for Wastewater Treatment: Municipal, Industrial and Agricultural. Chelsea, MI: Lewis Publishers.
- ^ Mountford, J. O., Lakhani, K. H., and Kirkham, F. W. 1993. Experimental assessment of the effects of nitrogen addition under hay-cutting and aftermath grazing on the vegetation of meadows on a Somerset peat moor. Journal of Applied Ecology 30: 321–332.