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Grove A general term for a patch of trees <br />iess than 2 acres in area. <br />Grub A tree or shrub whose aboveground <br />shoats are repeatedly kiiled by fire or <br />browsing but whose root system survives <br />and continues to send up new shoats. The <br />root system of a grub may be several <br />hundred years old; the above ground shoots <br />are generally much younger. <br />Habitat The locality, site, and paRicular type <br />of Iocal environment in which plants, <br />animals, and other organisms live. <br />Herb A plant Iacking a persistent above <br />ground woady stem. Herbs include broad- <br />leaved flowering plants, ferns, grasses, <br />sedges, and others. <br />High Water Level {HWL) The peak water <br />surface e{evation in a ponding area as a <br />result of a specific runoff event. Qnce the <br />peak is reached, ihe pond water elevation <br />eventualiy returns to its normaf (sta�ding} <br />water level. <br />Hydrology The science and study of water <br />in nature, incfuding its circuEation, <br />distribution, and its interaction with the <br />enviranrnent. <br />Hydrophyte A plant adapted to growing in <br />water or on wet soils that are periodica�ly <br />saturated and deficient in oxygen. <br />Hypolimnion L�wer cooler layer of a lake <br />during thermal stratification. <br />Ice block iake A lake that occurs in a <br />depression that was formed when a black of <br />giacial ice was buried or surraunded by till or <br />outwash sand, and then melted. <br />Ice scar A scar on a floodplain tree caused <br />by abrasion by ice floes during spring <br />flooding. <br />Impervious Surfaca A surface that is <br />impermeable to the downward seepage of <br />water; e.g., pavement and raof tops. <br />Inflorescence An arrangement of flowers <br />on a plani, such as in a cluster or along a <br />stalk. <br />Lacustrine Refers to features (such as <br />sedirnents, fandforms, plant communities, or <br />animal corr�munities} that were formed by or <br />are associated with a lake. <br />Landform A{and #eature, such as plain, <br />piateau, or valley, formed by a particular <br />geolagic process. <br />Life form Characteristic structural features <br />and growth pattern of plani species (e.g., <br />broad-leaved deciduous shrub}. <br />Glossary <br />Litter layer Relatively undecamposed <br />organic matter and debris on top ofi soil <br />layer. <br />Loading The amount of a pollutant or other <br />substance delivered to a 1ake, usuaily <br />expressed as a weight per unit time (i.e. <br />pounds per year). The loading of a given <br />constituent to a receiving water is a func#ion <br />of tne valume of incoming water and the <br />concentration of the constituent in the <br />incoming water. <br />Loess �ine materia! consis#i�g <br />predominantly of silt with fine sand and clay. <br />Loess is often deposited by wind. <br />Macrophytes Higher pla�ts which grow in <br />water, either submerged, emergent, or <br />floating. Reeds and cattails are exam�les of <br />emergant macrophytes. <br />Marsh A plant community of shalEow <br />weiland basins, dominated by herbaceaus, <br />emergent aquatic plants such as cattails and <br />bulrushes. Marshes usually have sianding <br />water throughout the growing season. <br />Meltwater Water released by melting glaciai <br />ice. <br />Mesic A general term describing upland <br />habitats that a�e interrnediate between wet <br />and dry; also used to descrit�e piants and <br />piant communities that occur in mesic <br />habi#ats. <br />Meso#ropF�ic l.alce Midway in nu#rient <br />ievels between eutraphic and <br />oligotrophiclakes. <br />Microhabitat A smalf, speciakized habitat. <br />Mineral soil A soil composed rrzostly of <br />inorganic matter, inclucEing clay, si1t, sand, <br />and gravel. Minera! soils usually have less <br />than 20% organic matter but may have <br />organic surface layers up ta 12 inches thick. <br />Minerotrophic A general term describing <br />wetlands with nuirient levels that faH <br />be#ween very low (such as in bogs) and very <br />high {such as �n seepage meadows). <br />Mitigation: Actions taken to reduce an <br />impact. Water quality mitigation measures <br />can be non-structural (such as street <br />sweeping, regulation of feriilizer use, and <br />creation/protection of natural buffers to filter <br />runoff) or structural {such as installation of <br />detention basins). Properly designed <br />detention basins are among the most <br />effective and reliable measures for <br />mitigating the water quality impacts ot urban <br />developments. <br />Mode1 A mathematical representation of an <br />event or process. <br />