• Rainbow over Half Dome

    Yosemite

    National Park California

Meadow Functions

 
Comparison of two meadow illustrations
Contrast a pristine meadow against a degraded meadow. Meadow functions typically assist surface storage, reducing downstream flooding, re-charging the aquifer during floods, supporting a shallow water table with mesic (or native) vegetation that minimizes erosion.
 

Meadows perform a variety of functions from flood control to groundwater recharge and also provide incomparable wildlife and plant habitat. Different meadows may provide some or all of these functions depending on the type of meadow:

Flood control: Meadows, in particular wet meadows and fens, reduce flood damage by storing flood waters and then slowly releasing the stored water. In this sense, wetlands perform the role of a natural flood reservoir. Just as a series of manmade flood reservoirs can reduce peak flow, meadows can reduce the peak flow of excessive flooding. Unlike a traditional reservoir, however, meadow plants also suck water out of the soil. Even if meadow plants use some of the water to reduce total storage, the critical role they are thought to play is in delaying the timing of spring runoff. In California, where it may barely rain from April to October, slowing the timing of runoff is essential for maintaining a steady supply of water through the dry season.


Water Quality (Pollution control): Meadows can improve water quality because of their ability to trap sediments. As the velocity of incoming waters is slowed, sediments are deposited. These sediments may contain physically or chemically attached toxicants (heavy metals, pesticides, and toxic organic substances). These toxicants may be "removed" by chemical breakdown, decomposition by soil microbes, or assimilation into plant tissues. Retention of nutrients occurs, too, within sediments and plant tissue—the transformation of inorganic nutrients to organic form, and the transformation of nitrogen to gaseous form. Nitrogen and phosphorous, generally the nutrients in greatest abundance, are taken up and stored by wetland vegetation. This function improves downstream water quality by filtering out potential pollutants.
 
graphic of meadow landscape above and below surface

Follow how precipitation (rain or snow) flows within a meadow landscape.

Groundwater Recharge: Groundwater recharge is the movement of surface water to groundwater by percolation to the underlying water table. Meadows can either serve as groundwater recharge areas (where water percolates down) or discharge areas (where groundwater percolates up) depending on the type of meadow. Three parameters that influence the movement of groundwater to and from a wetland: the elevation of the wetland relative to the groundwater; the mass and pressure of water; and the physical characteristics of the underlying soils and bedrock.

Erosion Control: Many meadows are tightly associated with lakes and streams. Meadow vegetation can play an important role in stabilizing stream banks and lake shores. This shoreline "anchoring" dissipates the erosive energy of moving water, and the erosion of adjacent uplands is minimized.

Fish and Wildlife Habitat: Some meadows (those with open water) provide habitat for amphibians and other aquatic invertebrates. For terrestrial wildlife, wetlands provide water, cover, and food. They provide vital resting, breeding and feeding areas for migrating waterfowl. No single wetland provides all habitat requirements for any species; adjacent uplands, wetlands, buffers and corridors are also important in determining the meadow's ability to function as wildlife habitat. Because meadows create habitat "islands" that are distinct from the surrounding areas, the connectivity of meadows with respect to one another may determine how some wildlife can disperse across the landscape.

Recreational Value: Wetlands provide consumptive recreational uses like fishing. Non-consumptive uses, including swimming, boating, bird-watching, and hiking, typically do not alter the meadow resources directly. Non-consumptive uses are the most difficult to quantify, and yet they may be the most important value of all. Mountain meadows have inspired human culture all over the world for thousands of years. They have also inspired a long history of American art and wilderness philosophy.

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