Effects of the northern pocket gopher (Thomomys talpoides) on alpine soil characteristics, Niwot Ridge, CO

Effects of the northern pocket gopher (Thomomys talpoides) on surface soil characteristics were examined at the alpine site of Niwot Ridge, CO. We measured erosion of soil from gopher mounds and compared the characteristics of gopher mound (disturbed) and undisturbed soils in two major plant community types. Our measurements of erosion indicate long-term susceptibility of gopher-disturbed soils to redistribution by water and/or wind in this ecosystem. Ecosystem heterogeneity introduced by the gopher is reflected in significantly lower SOM in gopher mounds than in surrounding undisturbed soils, a characteristic which appears to be causally associated with other effects of gopher disturbance including changes in soil texture and significantly lower clays, total C, total N, total P, and labile P. In contrast to plant-available P, NO3- was higher and steadily increased for the short term in both gopher mound soils and those beneath the mounds. These pools of NO3- then decreased to pre-disturbance levels by the following spring. Collectively our results indicate that, through the physical manipulation of soil and subsequent effects on soil resources, the northern pocket gopher functions as an agent of increased ecosystem heterogeneity and soil mass and nutrient redistribution at Niwot Ridge.