Effect of Vole Abundance in October, Snow Accumulation and Rodenticide Application on the Gnawing Damage on Planted Trees

Abstract

Gnawing by the gray red-backed vole Craseomys rufocanus bedfordiae on planted trees have caused serious damage on forestry in Hokkaido, northern Japan. Rodenticide have been applied to control the damage, based on vole abundance monitored. However, it has not been fully clarified the quantitative relationship between vole abundance, rodenticide application and occurrence of damage. Snow condition could affect the occurrence of damage because the damage usually occur in winter. This study analyzed data of vole abundance and damage on planted trees during 1991-1999 in Hokkaido, Japan, to demonstrate the effect of vole abundance, rodenticide application, tree species, stand age, maximum snow depth and length of snow period using the generalized linear model. Damaged trees increased with vole abundance, and rodenticide reduced damage. Older stands were less vulnerable. Preference of voles for conifers was in the order of Cryptomeria japonica, Picea abies, Larix kaempferi, Abies sachalinensis, L. gmerinii and a hybrid of L. gmelinii and L. kaempferi, and P. glehnii. More damage occurred in a site with deep snow cover with a given vole abundance, suggesting that the criteria for rodenticide application should be varied among regions.