Impact of pocket gopher disturbance on plant species diversity in a shortgrass prairie community.

We examined the impact of pocket gopher disturbances on the dynamics of a shortgrass prairie community. Through their burrowing activity, pocket gophers (Thomomys bottae) cast up mounds of soil which both kill existing vegetation and create sites for colonization by competitively-inferior plant species. Three major patterns emerge from these disturbances: First, we show that 10 of the most common herbaceous perennial dicots benefit from pocket gopher disturbance; that is, a greater proportion of seedlings are found in the open space created by pocket gopher disturbance than would be expected based on the availability of disturbed habitat. Additionally, these seedlings exhibited higher growth rates than adjacent seedlings of the same species growing in undisturbed habitat. Second, we tested two predictions of the Intermediate Disturbance Hypothesis and found that species diversity was greatest for plots characterized by disturbances of intermediate age. However, we did not detect significant differences in diversity between plots characterized by intermediate and high levels of disturbance, indicating that many species are adapted to or at least tolerant of high levels of disturbance. Third, we noted that the abundance of grasses decreased with increasing disturbance, while the abundance of dicots increased with increasing disturbance.