Effects of natural and anthropogenic gradients on native and exotic winter annuals in a southern California Desert

摘要: Native annual plant species constitute a large proportion of the diversity found in arid vegetation types within southwestern United States; yet, little is known about controls on patterns along natural and anthropogenic gradients. In this study we evaluated native richness exotic cover across overlapping gradients precipitation, wind, N deposition Colorado Desert southern California. Factors allowing to persist under high wind were also second, focused at one end gradient. We that nitrogen deposition, most important factors landscape, while local heterogeneity bare ground influenced deposition/windy, or high-disturbance, Patterns using non-metric multidimensional scaling, which showed was split into two axes: strongly correlated precipitation other with disturbance factors. The positively associated grass forb cover. total, these results indicate large-scale negatively affect but can due heterogeneity.