Relationship between rodent density, environmental factors and tree damage caused by rodent species

Abstract

The impact of rodent bark gnawing on common beech plantations was studied in the area of the Jeseníky Mts. in the course of four years. The extent of damage fluctuated significantly on 18 monitored plantations and was affected by a set of environmental factors, particularly by the altitude and herb layer character, which had a significant impact on the abundance and distribution of rodents. The ratio of grasses increased with decreasing altitude and conditioned the increasing abundance and occurrence of the field vole (Microtus agrestis), which proved to be the major pest in the area. Its impact was substantially more intensive (P < 0.05) than that of the more abundant bank vole (Myodes glareolus), whose abundance increased with increasing altitude, conditioned by higher numbers of its preferred dicotyledonous plants. However, the relation between an increase in abundance and the degree of damage was not significant in this species, unlike in the former. Although the damage of tree seedlings, caused by small rodents, can locally be serious, generally they do not generate an important impact on forest regeneration in mountainous regions.