Non-native plant densities significantly increased with survey year precipitation: as precipitation increased from 20 cm to 45 cm, plant densities increased from 161 plants m−2 to 362 plants m−2 (P < 0.01). Non-native annual grasses were not influenced by precipitation (P > 0.19). Precipitation amounts beyond 38 cm were confounded by the number of years since treatment; these high precipitation years only occurred two to three years post treatment. Precipitation less than 38 cm occurred throughout the study period. Curves represent the fit regression coefficients, the shaded area represents 95 % confidence intervals, and points represent an experimental unit mean for each survey year.