7. PRSR 04-11-2007 - Laserfiche WebLink

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Open-grown tree A tree that has matured in an open setting, such as a prairie or savanna. Open-grown trees tend to have broad crowns and thick, spreading lower limbs. Organic soil A soil in which the upper surface layers contain more than 25% organic matter. Outcrop Bedrock that projects above the soil. Outwash plain A plain formed of sorted and stratified material-such as layers of sand and gravel-carried from an ice sheet and deposited by glacial meltwater. pH A measure of the acidic or basic nature of the water; it is defined as the logarithm of the reciprocal of the hydrogen-ion concentration in moles/liter. Parent material The weathered rock or partly weathered soil material from which topsoil develops. Parts per billion (ppb) a unit of concentration, sometimes expressed as micrograms per liter (ug/I). Parts per million (ppm) a unit of concentration, sometimes expressed as milligrams per liter (mg/I). Peat soil A dark brown or black organic soil consisting largely of undecomposed or slightly decomposed plants. Peat soils usually form where persistent excessive moisture slows or inhibits the decay of plant material. Persistent vegetation Wetland vegetation formed by emergent hydrophytic plants with stems that normally remain standing until the beginning of the following growing season (e.g., cattails and bulrushes). Phosphorus A nutrient essential to plant growth. Phosphorus is the nutrient most commonly limiting plant growth in lakes. Phosphorus Export The amount of phosphorus carried off of a given area of land by stormwater. Phytoplankton Open water algae; it forms the base of the lake's food chain and produces oxygen. Prairie An upland plant community composed of grasses and forbs. Prairies generally lack trees; shrubs, if present, are not prominent. Presettlement A term used for convenience to denote the time period before Euro-American settlers moved into the Region. The Region was actually settled by American Indians for thousands of years before European-Americans arrived. Range (geographic) The limits of the geographic distribution of a species or group. Rate Control: A term that refers to controlling the rate at which water is discharged from a watershed. Rate control is often accomplished by creating ponds-either by excavation or berming- to temporarily store runoff, then discharging the stored water at a slower rate to downstream areas. Further reductions in the rate at which water is released from a pond can be accomplished by reducing the size of the outlet, such as through installation of a wall in the outlet structure with a hole (orifice) through it. Reintroduced species Species that had been eliminated from areas where they occurred historically and were later released back into the area by humans. Remnant A portion or fragment of a natural community that has survived while the rest of the community has been destroyed by logging, urban development, clearing of land for cultivation, and other human activities. Residence Time The amount of time it takes for water flowing into a lake to equal the lake volume. The shorter the residence time, the more incoming water the lake is receiving relative to its volume. Rhizome A horizontal underground plant stem. Savanna An upland plant community formed of prairie herbs with scattered trees or groves of trees. The canopy cover of trees in a savanna is generally between 10 and 70%. Secchi Disc A device measuring the depth of light penetration in water, typically a 9-inch, white circular plate attached to a rope. Used to measure water transparency. Sedge Any of a number of grasslike plants of the family Cyperaceae. Top of the World Park Addition Natural Area Management Plan 5