Effect of gnawing byMicrocavia australis(Rodentia, Caviidae) onGeoffroea decorticans(Leguminosae) plants

The impact of gnawing byMicrocavia australison the survival ofGeoffroea decorticansplants was studied in the Monte Desert of Argentina. Sampled plants (N=105) were selected randomly from two different colonies ofM. australis. For each plant sampled the following properties were measured: the diameter of the trunk at ground level; the distance to the nearest burrow ofM. australis; the proportion of the trunk perimeter that had been gnawed; and the condition of the plants. It was found that gnawing byM. australishas a negative impact on the survival ofG. decorticansplants. Damage of the plants is inversely related to the distance from the burrow systems (rs=− -030.05283,p< 0.05003) and to the proportion of the trunk perimeter gnawed (rs=− -030.05554,p< 0.050001). The differential survival of plants with a larger diameter trunk and of plants farther away fromM. australiscolonies may have long-term effects on the abundance and distribution ofG. decorticans.