Predisposition assessment systems (PAS) as supportive tools in forest management-rating of site and stand-related hazards of bark beetle infestation in the High Tatra Mountains as an example for system application and verification

Natural disturbances such as bark beetle infestations, feeding of vertebrates, storm throw, or snow breakage constitute important determinants for decision-making processes in forest management. Knowledge concerning the mechanisms of disturbance agents and the spatial distribution of predisposed stands allows for both an optimized input of labor and financial resources in forest management and may support the definition of core areas and surrounding buffer zones in protected areas. In order to face the demand for tools that illuminate the complex causal relationships between disturbance agents and predisposing site and stand-related characteristics, knowledge-based expert models for hazard assessment were developed. Key factors for the predisposition of forests to diverse biotic and abiotic agents were identified by an extensive literature research and expert discussions, and summarized by way of checklists. We discuss the basic assumptions of our predisposition assessment systems (PAS), using the specific model for the eight-toothed spruce bark beetle (Ips typographus) and the results of the system's application and verification in the High Tatra Mountains. We demonstrate that the spatial distribution of predisposing indicators significantly corresponds to the pattern of bark beetle attacks in the research area. The assessment system offers high flexibility of the underlying database and for spatial resolution, allows for a retrospective analysis of forest damages, for various possibilities of application (e.g., as a checklist, spatial analysis, etc.), and for easy incorporation of new scientific findings and empiric knowledge.