ANTHROPOGENIC EFFECTS ON THE BIODIVERSITY OF RIPARIAN WETLANDS OF A NORTHERN TEMPERATE LANDSCAPE

Land uses such as forestry and agriculture are presumed to degrade the biodiversity of riparian wetlands in the northern temperate regions o f the United States. In order to improve land use decision making in t his landscape, floral and faunal communities of 15 riparian wetlands a ssociated with low-order streams were related to their surrounding lan d cover to establish which organismal groups are affected by anthropog enic disturbance and whether these impacts are scale-specific. Study s ites were chosen to represent a gradient of disturbance. Vascular plan ts of wet meadow and shrub carr communities, aquatic macro-invertebrat es, amphibians, fish and birds were surveyed, and total abundance, spe cies richness and Shannon diversity were calculated. For each site, an thropogenic disturbances were evaluated at local and landscape scales (500, 1000, 2500 and 5000 m from the site and the site catchment) from field surveys and a geographic information system (GIS). Land use dat a were grouped into six general land use types: urban, cultivated, ran geland, forest, wetland and water: Shrub carr vegetation, bird and fis h diversity and richness generally decrease with increasing cultivatio n in the landscape. Amphibian abundance decreases and fish abundance i ncreases as the proportions of open water and rangeland increases; bir d diversity and richness increase with forest and wetland extent in th e landscape. Wet meadow vegetation, aquatic macro-invertebrates, amphi bians and fish respond to local disturbances or environmental conditio ns. Shrub carr vegetation, amphibians and birds are influenced by land use at relatively small landscape scales (500 and 1000 m), and fish r espond to land use at larger landscape scales (2500, 5000 m and the ca tchment). Effective conservation planning for these riparian wetlands requires assessment of multiple organismal groups, different types of disturbance and several spatial scales. (C) 1998 Academic Press.