Multifunctionality in European mountain forests — an optimization under changing climatic conditions

Forests provide countless ecological, societal, and climatological benefits. With changing climate, maintaining certain services may lead to a decrease in the quantity or quality of other services available from that source. Accordingly, our research objective is to analyze the effects of the provision of a certain ecosystem service on the economically optimized harvest schedules and how harvest schedules will be influenced by climate change. Based on financial portfolio theory, we determined, for two case study regions in Austria and Slovakia, treatment schedules based on nonlinear programming, which integrates climate-sensitive biophysical risks and risk-averting behavior of the management. In both cases, results recommend reducing the overaged stocking volume within several decades to establish new ingrowth, leading to an overall reduction of age and related risk, as well as an increase in growth. Under climate change conditions, the admixing of hardwoods towards spruce–fir–beech (Austria) or spruce–pine–beech (Slovakia) stands should be emphasized to account for the changing risk and growth conditions. Moreover, climate change scenarios either increased (Austria) or decreased (Slovakia) the economic return slightly. In both cases, the costs for providing the ecosystem service “rock fall protection” increases under climate change. Although in the Austrian case there is no clear tendency between the management options, in the Slovakian case, a close-to-nature management option is preferred under climate change conditions. Increasing tree species richness, increasing structural diversity, replacing high-risk stands, and reducing average growing stocks are important preconditions for a successful sustainable management of European mountain forests in the long term.