COBADIM · Characterizing Congo Basin Drought resilience: an Integrative Modelling approach

Characterizing Congo Basin Drought resilience: an Integrative Modelling approach

African rainforest, is the second largest on Earth and provides important ecosystem services through the absorption of atmospheric carbon, mitigating climate change. Both remote sensing data and tree ring stable isotope measurements have recently shown that these forests are currently being subjected to a long-term drying trend, raising fears over the drought resilience of tropical tree species and the persistence and magnitude of this carbon uptake. Drought events in tropical rainforests have a strong potential to alter forest structure and tree function, providing large feedbacks to the climate system. Slow-growing commercial tropical tree species with rotations of >50 years, put additional pressure on sustainable forestry practices and necessitate a forward looking approach with supporting policy. Yet, the needed long-term data and detailed physiological growth responses of tropical tree species to drought remain poorly measured. As such, there is a to obtain novel information on the function of tropical forests in the Congo Basin under a (drier) future climate in order to assess the ecosystem climate feedbacks and guarantee sustainable forest management practices. Limited research has been completed to characterise changes in forest structure and function in African rainforests. Predictions of future growth responses and carbon budgets of tropical forests are thus restricted by an incomplete understanding of how different species are limited by various resources. Connecting leaf phenological and wood anatomical traits together in a new comprehensive dataset can be used to inform ecosystem models, as current models lack the phenological response to drought required to simulate robustly annual and diurnal changes in primary productivity. The overall scientific goal is to enhance model estimates of carbon and water exchange and growth in response to drought in tropical tree species. This will be achieved using an interdisciplinary approach integrating (historical) trait based measurements and a novel [Ca] X-Ray Fluorescence (XRF) based tracer to drive a data-informed models. Here, we have shown that we used historical and retrospective (wood) data to provide important and novel ecological and botanical information, with the potential to expand this framework to other tropical species or regions. In particular, we used historical aerial footage and phenology data to provide important insights into the Land-Use and Land-Cover change and forest regrowth and recovery. Historical phenology data proved to be key in assessing climate responses across a large set of species. These data complement recent [Ca] XRF scans of central African wood cores (dating back to <1850). We could confirm the correspondence between seasonal rings and a strong [Ca] response and how to provide insight into seasonal to decadal changes in tree growth from ringless tropical trees.

Data: CORDIS, © European Union