Responses of forested wetland vegetation to perturbations of water chemistry and hydrology

Abstract

Nineteen mature Atlantic white-cedar swamps, located in four categories of undeveloped and suburban watersheds of the New Jersey Pinelands, were studied to determine the relationship between perturbations of water quality and hydrology and changes in species composition and community structure. Rank-orders of the 19 sites were compared for key variables (ground-water and surface-water NH4 and PO4, mean water-table level and water-table range). Rank orders for the sites were different for the various parameters, suggesting little congruence among water quality and hydrologic changes at wetlands within urban basins. Changes in species composition, measured as the number of invading species, were correlated with the number of perturbed chemical and hydrologic parameters and were not related to the absolute magnitude of any one parameter. Sites in developed watersheds supported a larger fraction of facultative upland and upland species than did sites in undisturbed watersheds; this change could affect wetland delineation of urban wetlands. Urbanization thus increases variability in environmental quality among sites of a given type of wetland and fosters an increase in proportion of non-hydrophytic vegetation within such wetlands.

Floristic comparison of freshwater wetlands in an urbanizing environment

“…One of the most visible aspects of altered structure is the invasion of native communities by non-native plant species (Kusler 1988, McColligan and Kraus 1988, Ehrenfeld and Schneider 1993. Although the threat to native diversity posed by introduced species is well-documented, the extent to which the flora of wetlands in urban settings is diluted by introduced species has received less attention.…”

“…Although the threat to native diversity posed by introduced species is well-documented, the extent to which the flora of wetlands in urban settings is diluted by introduced species has received less attention. For some wetland ecosystems, the influx of introduced plant species has been shown to be associated with altered hydrology and increasing intensity of surrounding land-use (Cooke and Azous 1993, Ehrenfeld and Schneider 1993, Taylor 1993, Houck 1996. Intensified land-use adjacent to wetlands or in associated stream drainage ways can result in physical changes to wetland environments that may affect plant species assemblages.…”

The impact of experimental sedimentation and flooding on the growth and germination of floodplain trees

“…Agriculture, land-use conversion and fragmentation are the most obvious landscape scale disturbances to floodplains ͑McIntyre and Nancy 1991; Cole et al 1997;Wardrop and Brooks 1998͒. Timber harvest in a watershed can alter the total flow, peak discharge rate, and the frequency and duration of flows within a stream ͑Troendle and Olsen 1994͒, and urbanization has been associated with hydrologic changes in wetlands ͑Taylor 1993; Ehrenfeld and Schneider 1993;Ewing 1996͒. On a longer time scale, Hupp et al ͑1993͒ found substantial increases in sedimentation rates in a forested floodplain over the past 50 years, with the highest rates directly downstream from urban-industrialized areas.…”

Establishment of Chamaecyparis thyoides on an Extremely Low‐Nutrient Sandy Site on the Atlantic Coastal Plain, U.S.A.

“…These will provide low levels of necessary nutrients over time. Higher dissolved nutrient levels, such as could occur if rapid release fertilizer were used, promote invasion by vegetation not characteristic of a healthy white cedar community (Ehrenfeld & Schneider 1991, 1993). Given the recent demonstration of natural colonization of C. thyoides by mycorrhizal fungi (Cantelmo & Ehrenfeld 1999) and the ability of such colonization to augment the mineral nutrition of the host plant in poor soils (Harley & Smith 1983), inoculation of the soil or planted trees with mycorrhizae might further increase the success of C. thyoides on new sites.…”