Disentangling the effects of wetland cover and urban development on quality of remaining wetlands

摘要

Effective landscape management decisions require knowledge of the relative effects of landscape variables on ecological responses, so that the most important landscape variables can be targeted for management. The relative effects of wetland cover and urbanization on remaining wetland quality are poorly understood because of correlations between these landscape variables. We determined the relative effects of wetland cover and urbanization on wetland quality by selecting a set of focal wetlands in which the percentages of the surrounding landscape in wetland cover and impervious cover were uncorrelated, at multiple spatial scales (extents). Wetland quality was inferred through abundance, taxa richness and taxa composition measures of vegetation and benthic macroinvertebrates. We found that reduced wetland cover was more detrimental than urbanization to remaining wetland quality, at least within the ranges of wetland cover (0 to 10%) and impervious cover (0 to 22%) in our study. In addition, we found that the spatial scale of these effects was large, in an area within 0.8 to 1.8 km of the wetlands. Our results indicate that policies aimed at reducing the impacts of urbanization around remaining wetlands will be only partly successful. Wetland management policies should also include wetland restoration in the landscape. Furthermore, our results indicate that management actions limited to buffer areas within tens of metres of wetlands will be only partly successful, because the influences of wetland cover and impervious cover on wetland quality extend much farther (0.8-1.8 km from wetlands). Policies applied to the whole landscape are needed.