The simplified representation of terrestrial ecosystems is a key source of uncertainty in future projections of the coupled carbon cycle/climatic system. Current Terrestrial Biosphere Models (TBMs) represent worldwide vegetation using just a dozen rigid Plant Functional Types (PFT), with empirical mechanisms calibrated on discrete observations. As a result, TBMs representing highly diverse ecosystems, such as tropical forests, may use only one clone of the same plant. Such an over-simplified representation results from a lack of observations in some regions, such as over Africa, which leads to widely diverging results for C cycling and nutrient/water limitations in future scenarios.

Simulating plant diversity is crucial for the assessment of global change impact on ecosystems and their feedback on climate.

LEAF2TBM targets the challenge for TBMs to simulate the effects of plant diversity on tropical forest ecosystem functioning and associated global biogeochemical cycles based on an integrated assessment of processes across different scales.

I will achieve this by using unique concomitant field observations of carbon dioxide and water vapor exchanges measured at multiple scales (from individual- to ecosystem-level) and state-of-the-art modelling approaches to ( 1 ) accurately quantify the effect of the functional diversity on ecosystems fluxes for two forests located in the Congo Basin and Amazon; ( 2 ) disentangle the roles of species composition and environment on ecosystems fluxes; and ( 3 ) provide a robust estimate of the global C budget uncertainty for tropical forests in TBMs.

LEAF2TBM will enhance EU scientific excellence and will be a crucial step for guiding the development of the next generation TBMs that are central for policy decision making.