Conservation of aquatic and riparian systems: the need to evaluate alternative management strategies

Authors: Astrid Kodric-Brown, James H. Brown

Year: 2008 (xl)

Abstract

A recurring theme in the management and restoration of aquatic and riparian habitats in the southwest is fencing, to exclude cattle and other large grazers. When present, these megaherbivores typically remove much of the surrounding vegetation. Removal of grazing and browsing mammals and continued exclusion by fencing typically results in extensive growth of riparian vegetation, reduction of open aquatic habitat, and decrease in biodiversity. Local extinctions of species or reduction in population sizes have repeatedly been documented for fish and amphibians, and likely hold for invertebrates as well. Small springs, streams, and seeps are especially vulnerable to the impacts of fencing, but large ones are also affected. Although there are numerous anecdotal accounts, there are few studies that quantify community structure before and after fencing and even fewer long-term studies of changes in vegetation and aquatic fauna after fencing. Here we stress the need for long-term experimental studies, which will provide background data to guide current management activities, such as fencing and megaherbivore exclusion, controlled burning, and mechanical and/or manual removal of vegetation.