Simulating Central-European forests in the 21st century – What are the effects of climate change and management?

Large-scale scenario analysis to project development of European forest resources and explore the effect of climate change and forest use scenarios is a key requirement for policy making and has attracted much attention recently.

In a recent study we harness the individual-tree based ecosystem model PICUS v1.5 to simulate 20 mill ha forests in five Central European (CE) countries (Germany, Czechia, Slovakia, Austria, Slovenia). In a quasi-spatial frame work we assigned 46 mixture types which had been defined based on the national forest inventory (NFI) data to 8x8 km grid-cells and distribute these mixture types over 1x1km sub-cells considering CORINE landcover types and regional age-class distributions. A gap-filling algorithm had been used to complete the information base for all 5 countries. PICUS includes disturbance modules for spruce bark beetles and wind storms. Current climate and three transient climate change scenarios were prepared for each 1x1km cell. Currently applied management regimes (BAU) had been operationally defined for the mixture types based on reports and interviews with experts from the five countries. BAU includes also a share of not actively managed forests. Five management response options from owner´s perspective were defined, including a no management option. BAU and the response options were then combined in six adaptive management scenarios for the entire CE forest area.

Under conditions of moderate climate change volume stocks can be retained under BAU management. If precipitation decreases, a drastic reduction of growth at lower elevations results, in parallel with a sharp increase of salvage harvests. Stocks decrease due to reduced increment and high tree mortality. Adaptive management is replacing productive coniferous and broad-leaved species by more drought and heat tolerant broadleaves which overall are less productive. The more extreme future climate develops the sooner adaptive management approaches reduce potential losses and stabilize production and stocks and perform better than the currently practiced management would. Non-native species such as Douglas fir improve the net effect of adaptation strategies further.

Beyond selected results we scrutinize currently available means and conclude on useful improvements.