Predisposition assessment of mountainous forests to bark peeling by red deer (Cervus elaphus L.) as a strategy in preventive forest habitat management

摘要

This paper presents a method to assess the predisposition of mountainous forests to bark peeling by red deer (Cervus elaphus), which illustrates options in preventive forest habitat management. We developed an expert system, based on expert interviews and literature analyses. We selected the most important site- and stand-related predisposing factors for bark peeling of red deer, considering the relation of food dependent and food independent settling stimuli. Within the mechanistic expert system, knowledge on predisposing effects of certain site and stand features is represented in the form of an award-penalty point system. In the current paper, we present the predisposition assessment system for bark peeling and the verification of the system with data of the inventory of natural resources of the Limestone Alps National Park (Upper Austria). Three site-related indicators, i.e. terrain features, roughness/smoothness of relief, and local climate, and six stand-related indicator, i.e. tree age, canopy cover, proportion of conifers, cover of herb layer, method of final cutting, and harassment, were included in the system. Both the chosen indicators and the overall assessment clearly reflected the predisposition in terms of relative frequencies of peeled and unpeeled sample plots. A supplemental logistic regression run with the occurrence/absence of bark peeling as response variable and the assessed predisposition scores from the PAS as explanatory variable proved the discriminatory value of the PAS.