Modelling the incidence of butt rot in plantations of Piceaabies in Denmark

Abstract

An empirical model is presented to forecast the incidence of butt rot at the stand level. In addition, the impact of different thinning regimes and stump treatment on the incidence of butt rot was evaluated. The model is based on data from 166 permanent forest yield research plots of pure even-aged Norway spruce (Picea abies (L.) Karst.) plantations in Denmark, within which the incidence of butt rot at stump height in thinned trees has been recorded after each thinning since 1947. In total, 79 000 stumps from 895 thinnings were studied. Regression analyses were carried out with the incidence of butt rot at a given point of time as the dependent variable and variables describing site, stand, and silvicultural treatments as the independent variables. Predictions carried out with the model imply that Norway spruce planted on old hardwood forest sites show the fastest development of butt rot and that the more heavily or more often a stand is thinned, the faster will be the development of butt rot. Furthermore, stump treatment with urea or sodium nitrite and thinnings carried out during January–March reduce the rot development.