...we hypothesized that microarthropod densities and numbers of taxa would be highest at the base of a closed basin watershed where organic matter and water accumulate (run-on area) and lowest at the top of the watershed (run-off area), providing the soils sampled were under the same plant species.... we hypothesized that as the soils dried following a rain event, the number of taxa and population densities of microarthropods would remain high for longer periods at the base of the watershed than at the top. The data collected in the study force us to reject our original hypotheses, i.e., that microarthropod population densities and number of taxa should be higher at the base of the watershed, exhibit a greater increase in size in response to precipitation and remain active for a longer time than on the upper slopes of the watershed. The relationships found in this study were almost the reverse of those hypothesized. Although soil organic matter and percent soil moisture were consistently higher at the base of the watershed, soil microarthropod populations were either lower than or equal to those found on the upper slopes.