Modelling changes in roe deer habitat in response to forest management

Abstract

We evaluated the change of roe deer habitat in response to three forest management scenarios: no harvest, clear-cut and single tree selection. For this purpose we simulated forest and understory vegetation in response to management for a 50-year period in an alpine forest region using the individual tree growth model PROGNAUS with an extension for understory vegetation. We also represented the spatial distribution of forest stands in a geographic information system. Habitat suitability and the forest's predisposition to browsing were then evaluated using models developed by Reimoser and Zandl [Reimoser, F., Zandl, J., 1993. Methodisches Grundkonzept für ein Expertensystem “Wildökologie und Waldverjüngung”, Anwendungsbeispiel FIW II-Fallstudie 1 (Schöneben/Oberösterreich). FIW Forschungsberichte 1993/4, Österreichische Gesellschaft für Waldökosystemforschung und experimentelle Baumforschung, 104 pp.]. These models aggregate eight habitat variables (canopy cover, canopy cover of evergreen trees, stand structural class, eight types of understory vegetation, density of forest margins, aspect, elevation and meso-relief) to four life requisites for roe deer: forage, cover from predators, shelter from adverse weather and daytime loafing area. These variables are then weighted and combined to form an overall habitat suitability and browsing predisposition score. Results of the simulation showed that for roe deer: quantity and quality of food supply were similar for all three scenarios. No harvest produced the best thermal cover. “Clear-cut management” resulted in the best hiding cover and high values for the living area index. For single tree selection thermal cover for roe deer was lowest. Clear-cutting was best for overall habitat quality. The ratio between forage and food independent settling stimulus was however disadvantageous in this management system. Clear-cut management therefore is attractive for roe deer, but facilitates over abundant roe deer populations which consequently cause damage to forests.