Effects of pocket gophers on desert soils and vegetation

The effects of pocket gophers (Geomyidae) on soils and vegetation were studied on Chihuahuan Desert and Sonoran Desert catenas for comparison with the effects of pocket gophers on soils and vegetation in mesic environments. Two species of gophers, Thomomys bottae and T. umbrinus, ejecta mounds were located on upper slopes of piedmonts where runoff from mountains increase soil moisture. Geomys arenarius ejecta mounds were restricted to small valley bottoms on ridge and valley mesa topography. Soil bulk density of ejecta mound soils was lower than undisturbed soil at the Chihuahuan Desert sites but not at the Sonoran Desert site. Significantly higher annual plant cover were recorded only for ejecta mounds of the Chihuahuan Desert piedmont. The effects of pocket gopher burrowing differed between the species, with G. arenarius sites showing greater extent of soil disturbance at a local scale, but effects of these disturbances on desert soils vegetation are dependent upon the properties of the undisturbed soil. These findings of limited impacts of burrowing on soil chemistry contrast with the situation in more mesic areas.