干旱区生态环境知识资源中心

The purpose of this study is to describe plant community structure within Capitol Reef National Park and identify possible effects of disturbance. We used Capitol Reef Field Station (Capitol Reef FS) as a proxy for current and historic disturbance. We collected data using two, 100-m transects located at differing proximities to Capitol Reef FS in each of four community types: pinyon-juniper, sagebrush, riparian, and grassland. Species frequency and percent cover were recorded within each transect using 20, 4-m(2) plots. We used ordinations to describe gradients in community structure as they relate to the environment and disturbance. We compared community structure and environmental factors by vegetation type, proximity to Capitol Reef FS, and through time. We found that the two main gradients in community structure were represented by a soil nutrient and texture gradient and an annual species and phosphorus gradient. Specifically, the concentrations of many soil nutrients were inversely related to soil texture size, while the amount of available phosphorus was positively associated with litter cover and the prevalence of annual species. Surface cover attributes, along with percent of annual and introduced species, differed among the vegetation types. Although we found that species composition is associated with proximity to Capitol Reef FS, no environmental factors differed by distance to the field station except for litter cover. Additional data are needed to separate the legacy effects of historical disturbance from current use of the field station.