Modelling spruce bark beetle infestation probability

Spruce bark beetle (Ips typographus L.) risk model, based on pure Norway spruce (Picea abies Karst.) stand characteristics in experimental and control plots was developed using classification and regression tree statistical technique under endemic pest population density. The most significant variable in spruce bark beetle infestation risk model was spruce basal area. Model, good enough for forest management practices, rate spruce stands to: a) stands of low bark beetle risk (probability of infestation p=20%) - basal area of spruce less than 17.8 m(2)/ha; b) stands of moderate bark beetle risk (p=55%) - spruce basal area greater than 17.8 but less then 46.9 m(2)/ha; c) stands of high bark beetle risk (p=83%) - spruce basal area greater than 46.9 m(2)/ha. Further model clarification need research under epidemic spruce bark beetle condition levels.