TropDemTrait · Tree growth and mortality in the face of climate change: A pantropical journey at the crossroad of trait-based and demographic approaches

Tree growth and mortality in the face of climate change: A pantropical journey at the crossroad of trait-based and demographic approaches

Tropical moist forests affect the terrestrial carbon cycle through the processes of tree growth and mortality, and are home to the majority of terrestrial biodiversity. Understanding tropical forest dynamics – how trees grow and die – is essential as tropical trees are the largest living carbon storage and reabsorption system of terrestrial ecosystems, but they are also major sources of uncertainties in Earth System Models. To better predict the role of these forests in climate change, complex processes must be quantified, which is possible through diverse datasets that use both traditional and novel approaches to measuring environmental, biological, and physiological data. Sophisticated statistical analyses, and computationally intense programming are required to integrate these diverse data sources, capture uncertainty, and build robust causal inference of the future of tropical forests processes. The project overarching goal was to understand how the demography of different tropical forests and tree species respond to stresses caused by climate change. It aimed to provide causal insights into the processes shaping forest dynamics across multiple spatial scales: from the local neighbourhood of trees to differences and commonalities among and across species and tropical regions and continents – up to a pantropical scale. The project had three overarching objectives. The first objective consisted in understanding the effects of climatic anomalies (temporal climatic variations around a local historical baseline) and the neighbourhood crowding of trees on the community-level growth and mortality of tropical forests. It also aimed to characterise differences among forests, regions, and continents with respect to responses to heat- and water-related stresses, using up to 50 years of permanent plot monitoring in Central Africa, South America, Southeast Asia, and Oceania. The work also examined how tree growth sensitivity to climate anomalies may be moderated by local historical climatic conditions. The second objective aimed to leverage a unique international dataset of tree species’ functional traits related to their resource acquisition strategies to provide physiological insights into the variation of growth and mortality sensitivity to climate among tropical forests’ species. This would allow mechanistically grounded forecasts of future floristic and functional tree compositions under contrasting future climate scenarios. This objective further aimed to test for temporal trends of change in species demography over the past decades, and to use species traits to understand these potential changes. Finally, the project aimed to define whether proxies of whole-plant relative allocation to photosynthesis can improve the capacity of leaf traits to predict growth and survival variations, by combining leaf traits with tree crown metrics. This would yield higher prediction accuracy of demographic rates than the commonplace use of leaf traits alone.

Data: CORDIS, © European Union