The importance of climate variability changes for future levels of tree-based forest ecosystem services.

The climate is changing, yet to which degree and in what pattern remains uncertain in many areas. In forest science, mainly impacts of long-term mean changes in temperature and precipitation distributions are studied. This paper therefore presents a sensitivity analysis to determine the importance of accounting for variability changes. A 10*10 matrix of different mean annual temperatures and precipitation sums is set up, covering the temperate forest zone of Europe, and the current level of several ecosystem services (ES) is calculated. Subsequently, mean and variability of temperature and precipitation distributions are changed in different steps, and new ES levels calculated. The results show that for the study of climate change impacts on forest ES, climate parameter variability is of secondary importance. The trends are well represented with scenarios of mean climate parameter changes only; however, on moisture-limited and heat-stressed sites impacts of changes in variability gain in importance. Most of these impacts are negative, and can be observed not only in monocultures already at their physiological limit, but also in diverse stands. Different ES, however, show different sensitivities towards changes in mean and variability, underlining the need to develop adaptation measures tailored to the sites and ES of interest. [ABSTRACT FROM AUTHOR]