Assessing critical thresholds of tropical ecosystems integrity using water content estimated from field and microwave remote sensing data

Several ecosystems worldwide are subjected to droughts with certain frequency, and drought stress is a major driver of ecosystem functioning decreases, productivity losses, and disruptions in the carbon balance. Global climate change might aggravate issues related to drought stress, since more frequent and extreme droughts are expected in the future due to changes in the climate, and we still lack knowledge on many aspects of plants and ecosystems response to drought. For instance, much is still unknown about ecosystemlevel thresholds in water content that can lead to decreased vegetation productivity (and potentially, plants mortality) and to a higher risk of burning. Thus, we aim at answering two main research questions: (1) What are the thresholds in the system water content that lead to a decrease in ecosystem's productivity and/or leaf area, and an increased flammability risk? (2) How abiotic (e.g., soil) and biotic (e.g., species composition) factors influence these thresholds? To answer these questions, we plan to use field data combined with state-of-the-art microwave remote sensing data and time series analysis. First, remote sensing estimates of ecosystems' relative water content will be validated. Second, the remote sensing estimates will be used to assess the ecosystem-scale critical thresholds in several vegetation types in central Brazil (the Cerrado). Finally, the role of biotic and abiotic factors in shaping these thresholds will be assessed.