| Zdroj: |
Conservation Ecology (11955449); 12/4/2003, Vol. 8 Issue 2, pN.PAG, 0p, 1 Diagram, 3 Charts, 5 Graphs, 2 Maps |
| Abstrakt: |
Although it has been repeatedly demonstrated that urbanization has negative environmental consequences, the conversion of land to urban use is increasing worldwide and is not likely to abate. We tested the hypothesis that different urban typologies, i.e., distributions of human population and infrastructure, differentially influence the water quality and ecological functionality of emergent marsh wetlands in New York State's Hudson River Valley. Wetlands were studied in two watersheds, defined as landscapes bounded by ridge lines, containing traditional small-town development and two watersheds containing suburban typologies. Land cover attributes were evaluated by analyzing ground-truthed, orthophotoquad data with a GIS. Water quality, the cover and biomass of emergent vascular plants, phytoplankton biomass, zooplankton biomass, and planktonic trophic transfer efficiency were measured in the wetlands during the fall of 2000, the summer and fall of 2001, and the summer and fall of 2002. Of the 13 variables measured, five exhibited typological differences according to the results of student t-tests. The interactions between these variables were quantified by least squares regression. Two key attributes of urban systems, i.e., the amount of vegetated buffer between the urban landscape and receiving waters and the amount of land in urban use, appeared to strongly influence water quality and ecosystem function in the wetlands studied. Nonpoint source loading and the success of exotic emergent macrophytic invasions varied directly with urban land use and inversely with buffer width. Trophic transfer efficiency declined with urban land use and increased with buffer width. The amounts of buffer and urban land use in a watershed appear to vary systematically with urban typology. Thus, watersheds that were developed in accordance with suburban design criteria exhibited more urban land use and less riparian buffering than did watersheds containing comparably scaled... [ABSTRACT FROM AUTHOR] |
