Towards a deeper understanding of how climate change affects forests
Due to the enormous number and diversity of tree species in the world, understanding how each of them responds to non-biological factors and how they interact is a truly daunting task. One solution is to use functional traits to describe diversity. These define species in terms of how they interact with the environment and other species. With this in mind, the EU-funded DEMO-TRAITS (Tree demography, functional traits and climate change) project collected forest data to discover how tree traits determine trees' competitive interactions and responses to climate. The database covers all the planet's major forest habitats, from boreal to tropical rain forests, and includes more than 2 500 species and 3 million trees. Project partners analysed how the density of competitors and climatic conditions influence the growth and survival of individual trees. Competition covered all the major forest habitats on Earth. Analyses led to several findings. There is a negative correlation between an individual tree's rapid growth and its wood density in all habitats. Conversely, it has a positive correlation with its specific leaf area in most habitats. A trade-off exists between species' tolerance to climate stress and their competitive ability. Competition from within species was greater than among species, but the extent of trait dissimilarity (two species that differ in trait values) between species did little to weaken competition. Results show that trait dissimilarity consequences are either weak or missing in forests on a global scale. DEMO-TRAITS will help to predict climate change impacts on forest ecosystems and the role of functional diversity in forest productivity. Both forest resource managers and policymakers stand to benefit from the outcomes.
Keywords
Climate change, forests, DEMO-TRAITS, tree demography, functional traits