Vegetative edge effects and pocket gopher tunnels

Herbivory and soil movement by subterranean mammals influences structure an d species composition of plant communities they inhabit. Tunnels constructe d by pocket gophers (Geomys bursarius) in Kansas produced an edge effect wh erein biomass of the dominant plant species, big bluestem (Andropogon gerar dii), increased adjacent to tunnels, then decreased, before increasing agai n. This wave-like phenomenon was attributed to reduction of biomass of big bluestem above tunnels releasing plants adjacent to tunnels from intraspeci fic competition. We tested for edge effects on vegetation over tunnels of A ttwater's pocket gopher (Geomys attwateri) in a floristically diverse (>10 species of monocots, >30 species of dicots) prairie in coastal Texas. No co mmunity-level edge effect was detected; neither biomass, species richness, nor diversity of all plants, monocots alone, or dicots alone over tunnels d iffered significantly from that in quadrats 0 to 10, 10 to 20, 20 to 30, or 30 to 40 cm away from tunnels. Biomass of 4 individual species of plants p rominent in the diet of G. attwateri did not show an edge effect. We conclu de that tunnels of pocket gophers have a minor impact on plant biomass or c ommunity structure in the floristically diverse coastal prairie of Texas. T his result contrasts to the negative effect of deposition of mounds above g round on plant biomass in prairies elsewhere in Texas and Kansas.