Evaluating WINDA – a tool for assessing the probability of wind damage to forest stands

WINDA is an integrated system of models for calculating the stand-wise probability of wind damage of trees within a landscape (Blennow & Sallnäs, submitted). It integrates a modified version of the dose/response model HWIND (Peltola et al., 1999), the airflow model WASP (Mortensen et al., 1998), and a component for calculating the zero-plane displacement and surface roughness. WINDA uses a GIS for geographical computations. The calculations are made point-wise at exposed stand edges and the results are combined for each stand. The likelihood of damage is calculated using extreme value theory. The mechanistic modelling approach makes WINDA useful for evaluating effects on the probability of wind damage of silvicultural treatments and forestry activities as well as of a changed climate. This paper briefly outlines WINDA and evaluates output by comparing predicted damage with observed damage for two landscapes in southern Sweden