The interaction between root herbivory by rodents and plant communities

Although the vast majority of herbivorous rodents feed on aboveground plant parts several Families include, or are completely composed of, species that are subterranean and feed primarily on roots.  Subterranean herbivorous rodents have evolved independently on all continents except Antarctica and Australia. Because these rodents spend their lives in the dense, opaque medium of the soil, their influence on plants and soil may be underappreciated.   The direct effect of root herbivory, especially by relatively large animals that consume entire roots, can be profound, leading to significant reductions in plant fitness and high levels of mortality.  These effects, mediated through dietary selection and the spatial pattern of root herbivory, impact the composition and structure of plant communities.  The direct impact of subterranean rodents is amplified considerably by the indirect effects of excavations on the soil.  As burrows (which can extend scores of meters) are excavated the extracted soil is deposited on the surface as mounds.  The resulting pattern of vacant belowground burrows and patchily distributed mounds on the surface generates a mosaic of influences on the physical and biogeochemical characteristics of soil.  I will briefly describe the foraging and excavation behavior of subterranean rodents, focusing primarily on North American pocket gophers and sub-Sarahan mole rats.  I will then characterize the impacts of their activity on individual species of plants, plant communities, soil characteristics, and landscape-level features.