Long-term Effects of Pocket Gopher Control on Vegetation and Soils of a Subalpine Grassland

Abstract

In the half of an exclosure where pocket gopher populations were uncontrolled, dandelion was eliminated from the community and the aboveground peak standing crop of slender wheatgrass, mountain brome, Michaux sagewort, and Rydberg penstemon increased between 1942 and 1973. In the half of the exclosure where gophers were controlled yearly, most species of annuals were absent in 1973, Letterman needlegrass decreased, and slender wheatgrass increased. Tall forbs, mainly Oregon fleabane and sticky geranium, increased in both areas, but the greatest increase occurred where gophers were controlled. Soils within the exclosure were significantly higher in total porosity and significantly lower in bulk density in 1973 than soils in the adjacent area grazed by sheep. Organic matter, nitrogen, and phosphorus contents of the soil were significantly higher where gophers were present in the exclosure than where gophers had been controlled.