Document: SUS-3-69-14

The northern pocket gopher (Thomomys talpoides) as an organizer of alpine ecosystem and plant community structure.

SHERROD, S.K.* ^1,2 and T.R.SEASTEDT ³

U.S. Geological Survey, Moab, UT 84532, USA ¹
University of Denver, Denver, CO 80210, USA ²
University of Colorado, Boulder, CO ³

Abstract:
We identify the northern pocket gopher (Thomomys talpoides) as a keystone engineer in the alpine tundra of Niwot Ridge, Colorado, by virtue of its control over biogeochemistry, biodiversity, and vegetative community structure. The term keystone species, used to identify a unique and/or important species to the structure or function of its ecological system, has been criticized as vague and difficult to quantify. It is nonetheless a useful concept and we propose that designating a keystone organism is equally dependent on the explicit identification of the species' environment as on identification of the species itself. Keystone status is therefore a function of an organism's relationship with its resident ecosystem, which the northern pocket gopher exemplifies in Colorado's alpine tundra. Pocket gopher disturbances induce long-term erosion of soil mass, carbon, and nitrogen, thereby modifying local microtopography and nutrient distribution. Further, we have identified a potentially interdependent relationship between the pocket gopher and the forb growth form, both of which are most concentrated in the alpine moist meadows: Gopher disturbances suppress graminoids and cushion plants, whereas forbs are the most resilient to the aboveground disturbance. Trends in species richness following gopher disturbance were a function of scale, where mesoscale richness is positively correlated with disturbance and microscale richness is negatively correlated.

Keywords: keystone, gopher, disturbance, alpine

This abstract is being presented at: 9:00 AM in session:
Oral Session #21: Small Mammal Population Ecology.