Effects of pocket gophers (Geomys bursarius) on microtopographic variation

Mounds of soil created by pocket gophers during the process of construction of burrows represent small-scale variation in topography and resources that may influence vegetation by creating a broader range of microsites for germination and growth. We mapped gopher mounds and measured microtopographic variation on 4 by 4-m plots that had been fertilized annually with four levels of nitrogen addition for 11 years. Fertilized plots had more mounds and greater topographic variation than unfertilized plots, and greater mean height of soil than unfertilized plots and adjacent unfertilized aisles. These changes in microto-pography and height of soil, caused by the cumulative effects of locally greater activity by pocket gophers over more than a decade, illustrate one way in which burrowing animals can affect heterogeneity in soils