The influence of stream channels on distributions of Larrea tridentata and Ambrosia dumosa in the Mojave Desert, CA, USA: patterns, mechanisms and effects of stream redistribution

Drainage channels are among the most conspicuous surficial features of deserts, but little quantitative analysis of their influence on plant distributions is available. We analysed the effects of desert stream channels (?washes?) on Larrea tridentata and Ambrosia dumosa density and cover on an alluvial piedmont in the Mojave Desert, based on a spatial analysis of transect data encompassing a total length of 2775 m surveyed in 5 cm increments. Significant deviations from average transect properties were identified by bootstrapping. Predictably, shrub cover and density were much reduced inside washes, and elevated above average levels adjacent to washes. Average Larrea and Ambrosia cover and density peaked 1�2?1�6 m and 0�5?1�0 m from [...]