Use of Standardized Visual Assessments of Riparian and Stream Condition to Manage Riparian Bird Habitat in Eastern Oregon

摘要

The importance of riparian vegetation to support stream function and provide riparian bird habitat in semiarid landscapes suggests that standardized assessment tools that include vegetation criteria to evaluate stream health could also be used to assess habitat conditions for riparian-dependent birds. We first evaluated the ability of two visual assessments of woody vegetation in the riparian zone (corridor width and height) to describe variation in the obligate riparian bird ensemble along 19 streams in eastern Oregon. Overall species richness and the abundances of three species all correlated significantly with both, but width was more important than height. We then examined the utility of the riparian zone criteria in three standardized and commonly used rapid visual riparian assessment protocols-the USDI BLM Proper Functioning Condition (PFC) assessment, the USDA NRCS Stream Visual Assessment Protocol (SVAP), and the U.S. EPA Habitat Assessment Field Data Sheet (HAFDS)-to assess potential riparian bird habitat. Based on the degree of correlation of bird species richness with assessment ratings, we found that PFC does not assess obligate riparian bird habitat condition. SVAP provides a coarse estimate, and HAFDS provides the best assessment. We recommend quantitative measures of woody vegetation for all assessments and that all protocols incorporate woody vegetation height. Given that rapid assessments may be the only source of information for thousands of kilometers ofrnstreams in the western United States, incorporating simple vegetation measurements is a critical step in evaluating the status of riparian bird habitat and provides a tool for tracking changes in vegetation condition resulting from management decisions.