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TRACKING WETLAND CHANGES IN AN URBANIZING AREA USING NATIONAL WETLAND INVENTORY AND FIELD SURVEY DATA
Citation:
Kentula, M E. AND S. E. Gwin. TRACKING WETLAND CHANGES IN AN URBANIZING AREA USING NATIONAL WETLAND INVENTORY AND FIELD SURVEY DATA. Presented at 23rd Annual Meeting of the Society of Wetland Scientists, Lake Placid, NY, June 2-7, 2002.
Description:
Urban wetlands can experience rapid change with development. Using information from National Inventory Maps (NWI) in combination with rapid field surveys conducted in 1992 and 1998, we tracked changes over 16 years in small ( 2 ha), palustrine emergent/open water (PEM/POW) wetlands in the rapidly urbanizing area of Portland, Oregon. These were wetland types most often involved in development as indicated by Section 404 permits. NWI data based on 1982 photography showed that 26% of the total resource area (linear features and polygons) was composed of wetlands 2 ha, 57% (348 ha) of which was PEM/POW. Field data confirmed that 40% (139 ha) had been altered prior to 1982 as indicated by various symbols on NWI maps. Only 45% of the previously unaltered polygon area on 1982 NWI maps still existed in 1998 and 40% of those remaining polygons had hydrologic modifications extensive enough to change hydrogeomorphic type. Losses were countered by construction of mitigation projects which enlarged linear features present in 1982 and increased the area of PEM/POW by about 5 ha. Land use in the vicinity of the wetlands reflected development patterns. In the early 1990s commercial and industrial uses surrounded wetlands in developed settings. By the end of the 1990s, wetlands in residential settings equaled those in commercial and industrial. We tracked major changes in a wetland type using rapid and relatively inexpensive techniques. Such information can be used to target and design restoration efforts and other management actions.