7. PRSR 04-11-2007 - Laserfiche WebLink

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also used to describe plants and plant communities that occur in mesic habitats. Mesotrophic Lake Midway in nutrient levels between eutrophic and oligotrophiclakes. Microhabitat A small, specialized habitat. Mineral soil A soil composed mostly of inorganic matter, including clay, silt, sand, and gravel. Mineral soils usually have less than 20% organic matter but may have organic surface layers up to 12 inches thick. Minerotrophic A general term describing wetlands with nutrient levels that fall between very low (such as in bogs) and very high (such as in seepage meadows). Mitigation: Actions taken to reduce an impact. Water quality mitigation measures can be non- structural (such as street sweeping, regulation of fertilizer use, and creation/protection of natural buffers to filter runoff) or structural (such as installation of detention basins). Properly designed detention basins are among the most effective and reliable measures for mitigating the water quality impacts of urban developments. Model A mathematical representation of an event or process. Moraine Rock and mineral debris deposited directly by glacial ice. Moraines most often consist of unsorted rock and mineral particles. Muck Adark-colored organic soil of highly decomposed plant material in which the original plant parts are not recognizable. MUSA (Metropolitan Urban Service Area) The area designated by the Metropolitan Council of the twin cities area to receive urban services such as central sewer, urban streets, etc. Native habitat A habitat formed and occupied by native plants and animals and little modified by logging, farming, ditching, flood control, and the like. Native species A species that occurs naturally within a given region. 3Native vegetation Vegetation, composed of native plants, that has been little modified by human activities such as logging, farming, ditching, or the introduction of nonnative species. Natural area Geographic area in which the dominant plants and animals are native species. Natural community An assemblage that tends to recur over space and time of native plants and animals that interact with each other and with their abiotic habitats in ways that have been little modified by nonnative plant and animal species. Natural communities are classified and described according to their vegetation, successional status, topography, hydrologic conditions, landforms, substrates, soils, and natural disturbance regimes (such as wildfires, windstorms, normal flood cycles, and normal infestation by native insects and microorganisms). Nonnative species A species that has been introduced to an area by humans or that is present in the area as a result ofhuman-caused changes. Non-Point Source Pollution: Refers to pollution other than that caused by discharge of pollutants through a pipe from a closed system to a receiving water. Pollution caused by runoff from farm fields or paved streets are examples of this non-point pollution. Normal Water Level (NWL) The elevation of the surface of the standing water pool within a pond or wetland. Generally, the NWL is the elevation of the bottom of the primary outlet pipe or overland flow channel. Nutrient Budget: An itemized estimate of nutrient inputs and outputs (usually for a period of one year), taking into account all sources and losses. Nutrient Loading The input of nutrients to a lake Nutrient Trap A type of pond or wetland that is effective at removing nutrients from water. Nutrients Elements such as phosphorus and nitrogen that are required for plant growth. When excess amounts are transported in stormwater they may encourage excessive algae or other plant growth in receiving water bodies. Oligotrophic Lake A relatively nutrient-poor lake, usually clear and deep with bottom waters high in dissolved oxygen. s Many of the definitions used in this section are borrowed from Minnesota's St. Croix River Valley and Anoka Sand lain, Worcha et al, Minnesota DNR, 1995. Top of the World Park Addition Natural Area Management Plan 4