Pocket Gopher — Actor under the Stage. Studies on Niwot Ridge, Colorado Front Range, U.S.A.

Abstract

The Northern Pocket Gopher (Thomomys talpoides Richardson) is a small herbivory subterranean rodent. It is known as an eager digger and in areas with intense activity it is suspected of damaging young tree growth. Results from soil analysis and snow measurements are presented to describe the pocket gophers’ summer and winter environment within a ribbon forest in the forest-alpine tundra-ecotone on Niwot Ridge, Colorado Front Range. The distribution of snow and the structure of snow cover are influencing the pocket gopher’s life under cover. Soil analysis showed that pocket gopher activity modified the soil environment. The amount of coarse soil particles in the upper topsoil layers was increased compared to topsoil with no gopher disturbance. The distribution of organic matter within the upper 12 cm was more homogeneous in areas with gopher excavation. None of the damages found on young trees could be attributed to pocket gopher activities without question. The most obvious damages were reduced growth at the windward side (83 %) followed by crippled growth (60 %) and damages caused by snow fungi (32 %). In summary, the pocket gophers in the ribbon forests on Niwot ridge are actively modifying the soil environment by exposing mineral soil and increasing the likelihood of soil erosion by wind and water. There is, however, no evidence that pocket gophers are responsible for the visible prevalent damage on juvenile conifers.