Bio E179 Midterm Notes .docx

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Biological Sciences
Rahul Warrior

Lecture 1 Wetlands oThree general characteristics Wet at some point during the yearHydric soils formed by water processes that are different from upland habitat Hydric soils are anoxic do not have oxygen available to plants or invertebrates when they are wet Anoxic bc soil is thin Support hydrophytic vegetation vegetation that can or may be in wetland conditionswetland indicator species Wetland Types oDistinguished by water flow and vegetation oSurface water wetlandReceive water from precipitation and surface flows Include surface water slope and surface water depression wetlandsoGround water wetland Get water from underground sources like the water table or subsurface aquifer oBogs Surface water depression wetland rainfed Stagnant and acidic Water flow is low or nonexistent oFens Ground water depression wetland water flows in from underground water table oMarshes Nonwoody plants Emergent herbaceous vegetation Open system water flows in and out Slow by steady flow of wateroSwamps Woody emergent vegetation Open system Slow but steady flow of water Loss of Wetland HabitatoBefore European occupation there were over 200 million acres of wetland in US o54 converted to other habitats or developed by 1970oOnly 99 million acres by mid1970s oCA has sacrificed 91 of wetlands 97 in So Cal Riparian forest in Sacramento Valley is best documented losses with 15 riparian forest surviving Mono Lakewater diverted for human use has caused Mono to become drier and more basic Mitigation by returning freshwater flow into the lake has been a problem oWater column is separated into two bands that differs in salinity oPredicted to turnover within 50 years and kill most of the inhabitants brine shrimp oAfter turnover and mixing of dense basic water with freshwater on top lake will be recolonized with brine shrimp Causes of Wetland Habitat Loss oAgriculture Greatest causeLoss of 87 of wetlands oUrban Development 8 of loss oOther Development dams stream diversion etc 5 of loss Dams and other human caused hydrologic alterations affect 77 of 139 largest river systems in the US Europe and former Soviet Union Due to dams and water regulation from reservoir operation interbasin diversion and irrigation In hydroelectric plantsdams water levels can be dropraised rapidly to generate power causing risk to habitat and human health oDirect Threats Drainage for crop production timber production and mosquito control Dredging and steam channelization for navigation channels flood protection coastal housing development and reservoir maintenance Solid waste disposal roads and industrial development Construction of dikes and dams for flood control water supply etcDischarge of materials from domestic sewage and agricultural runoffMining of wetland soils oIndirect Threats
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