Effects of common vole on alfalfa crop

Abstract

Abstract From 1973-1974, that is, during a period of increase in the numbers of rodents and during their mass occurrence, examination was made of the damage done by the common vole Microtus arvalis in a field of alfalfa. The eightfold increase in the voles' density from spring to autumn (1974) was accompanied by a sixfold increase in the amount of damage done to the alfalfa yield during the period from the first to the third mowing. Analysis was made of two processes compensating for loss in alfalfa yield: the process of weed invasion on the crop and the regeneration of alfalfa. A straight-line relation was found between the amount of alfalfa losses and increase in weed biomass. The rapid regenerative process of alfalfa in spring, compensating for the damage done by rodents during the winter, declined as the growing season proceeded. The ratio of destroyed alfalfa to that consumed by voles increased from 1-2 in spring to 5-9 at the first mowing and to 14 at the third one. A model of the effect of a vale population on an alfalfa crop is presented in this paper.