Forest vulnerability to compound extremes and disturbances in a changing climate

Forests play a crucial role not only in providing breathable oxygen, supporting biodiversity and regulating water and energy exchanges, but also in mitigating climate change. Currently, forests absorb 25% of human CO2 emissions, but their sequestration potential may be negated by more frequent and intense weather extremes and disturbances in the future. Mega-droughts, massive wildfires and widespread tree mortality reported in the last decade might be early warnings of the upcoming threats to forests under climate change. Yet, process-understanding about the interactions between climate, forests and key disturbances is limited. Consequently, impacts of compound extremes and disturbances on forest CO2 sequestration potential are not yet realistically simulated in future climate projections by Earth System models.To overcome this knowledge gap, ForExD proposes a cross-disciplinary conceptual framework placing disturbances as intrinsic components of coupled ecoclimatic variability. We will apply novel high spatiotemporal resolution remote-sensing data to reconstruct disturbance histories and explore emerging analytical tools to gain understanding about the interactions between climate, forests and disturbances. We will then develop mechanistic models of forest-disturbance interactions, which will allow simulating, for the first time, compound extremes and disturbances (fires, droughts, insects, storms) and impacts in a state-of-the-art land-surface model. The project will build on the PI's expertise on ecological monitoring and modelling and strong cross-disciplinary background on ecoclimatology and biogeochemistry to develop a systemic understanding of interactions between climate, forests and disturbances. ForExD will provide fundamental knowledge about forest dynamics and feedbacks between climate and the carbon-cycle. In doing so, ForExD will make a vital contribution to resolve long-standing uncertainties about forests' climate change mitigation potential.