Adaptation Strategies for Spruce Sites

Abstract

The selection of tree species is a fundamental decision in strategic forest planning. Climate change influences the suitability of species regarding growth potentials and natural risks. This leads to expectations of high economic losses in European Forests. In Germany, high shares of Norway spruce have been cultivated in suitable growing areas. This species is particularly vulnerable to climate-driven risks such as storms or bark beetles. Frequently studied mitigation strategies for risk-averse forest owners are a reduction of rotation periods and a diversification of the tree species portfolio. However, studies on the economic impact of forest protection measures are rare. Our study seeks to analyze the economic consequences of intensified bark beetle monitoring with sanitation fellings as a future strategy in typical growing areas of spruce. The underlying simulation model integrates empirical survival time models and a bark beetle model into the mean variance portfolio method to derive rational species mixtures. In this framework, we show under which conditions it is advantageous to reduce the infestation risk of bark beetles for spruce by investing in intensive protection measures. As an alternative to bark beetle monitoring, we analyze which characteristics an additional tree species should have to compensate for the higher risks of spruce. The results indicate that, compared to increased shares of beech, forest protection measures and alternative tree species might be able to compensate for considerably more climate-driven economic losses.