Hochlagen 121

Scenarios for forest biodiversity dynamics under global change in Europe: identifying micro-evolutionary scale tipping points

Predicting the response of trees, the keystone elements of forests, to ongoing global change is a critical ecological, societal and economic issue. Forests cover nearly 40% of Europe and around 23% of emerged land worldwide. Further, most "hot spots" of biological diversitywhere biodiversity is both high and vulnerable are actually forests. Besides biodiversity sustainability, forests provide numerous ecosystem services, including carbon sequestration and freshwater availability.

Impacts of climate and land-use changes on forests are expected to be acute. Environmental tipping points may be reached where tree populations collapse suddenly with irreversible effects on ecosystem functioning. Adaptive potential could nonetheless be high in tree populations: besides tracking their ecological niche spatially through migration, tree populations could adapt to the ongoing climate change (CC) in the short-term through individual phenotypic plasticity, and/or in the long term through evolutionary response to climate-induced selection. However, observed and predicted rates of climate and environmental changes are much faster thannatural oscillations in the past. As a consequence, the question arises whether adaptation of tree species can keep pace with CC.

In TipTree, we plan to investigate to what extent trees have the evolutionary potential to adapt to ongoing CC, to investigate the existence of tipping points in adaptive genetic diversity below which adaptation to degraded environments is not possible anymore, and to assess how human actions interfere in the adjustment between the rate of evolution and the velocity of CC. A main originality of Tiptree is to investigate tree abilities of rapid adaptation (in 1 to 10 generations), in different parts of the range (and in particular in warm margins where tipping points are most expected). Another novelty of TipTree is the application of a new generation of simulations models that account for key environmental, ecological and genetic processes. Using these models, we will investigate the demographic and evolutionary dynamics of tree populations. Models will be developed for a range of forest management scenarios established by our stakeholder group and under different scenarios of CC provided by IPCC. These simulations will provide forecasts of tree persistence, ecosystem services (carbon sequestration, wood production, sustain of forest cover for recreation) and decision support for management.