TreEsilience · Global patterns of intraspecific variation in tree resilience to drought

Global patterns of intraspecific variation in tree resilience to drought

What is the problem/issue being addressed? Forests provide essential long-term ecosystem services, such as the conservation of biodiversity or the reduction of greenhouse gas emissions. Consequently, preserving forests has been the focus of many conservation policies (i.e. the Europe 2020 Strategy). Drought events associated with climate change reduce tree growth and prompt tree mortality episodes, impacting globally and severely on forest ecosystems. TreEsilience project has studied the ability of trees to resist and recover from drought (tree resilience) that will be decisive to maintain the functioning of these ecosystems. Why is it important for society? The results have provided insights into novel strategies to improve forestry efficiency by identifying early signals of tree mortality, useful for forest practitioners, policy-makers and stakeholders in order to mitigate the detrimental effects of land degradation and desertification on human wellbeing due to climate change. What are the overall objectives? TreEsilience has explored tree climate-growth relationship and resilience to drought across tree species and populations as key for predicting the effect of climate change, in particular drought-induced mortality. First, climate sensitivity may depend on species-specific traits leading physiological and anatomical responses to temperature and water availability. Second, different tree populations may have faced contrasting climatic conditions, and then within-species response to climate change may differ geographically due to local adaptation. In order to reach this ambitious goal, TreEsilience has used an interdisciplinary approach that combines dendrochronology, phylogenetic comparative methods and species distribution modelling, thus bringing tools from the spatial and evolutionary ecology to the study of forest management and conservation. Conclusion. Our findings confirm that trees that died during water shortages were less resilient to previous non-lethal droughts, relative to coexisting surviving trees of the same species. This key result evidences the link between mortality risk and the previous observed differences in drought resilience strategies that can be reflected in tree-ring growth.

Data: CORDIS, © European Union