Effect of an herbivorous subterranean rodent on vegetation in relation to primary productivity

Abstract

Subterranean rodents modify the surrounding environment being classified, in some cases, as keystone species and/or ecosystem engineers. This role could be context-dependent if the changes produced shift throughout the species distribution range and are stronger under certain environmental conditions. Our objective was to analyse whether the effect of Ctenomys mendocinus on vegetation cover is context-dependent. Given that primary productivity may increase plants' ability to tolerate or compensate following herbivory, we hypothesize that the effect of C. mendocinus on vegetation cover will be context-dependent along a primary productivity gradient, with smaller effects in highly productive environments and larger effects in less productive ones. We compared the effect of C. mendocinus on plant cover among four contrasting environments and found that it depended on primary productivity in a predictable manner. In low productivity environments, the rodent significantly reduces vegetation cover, while it has no discernible effect in highly productive ones. These findings suggest that the effect of C. mendocinus on plant cover depends on primary productivity level and highlights the importance of accounting for the underlying environmental factors that influence the intensity of C. mendocinus–plant interaction.