This proposal spans the three largest biomes in Brazil, the Atlantic and Amazon Forests, and Cerrado savanna. Together these cover >85% of Brazil's territory and include many of the most diverse ecosystems on Earth, but all have seen large losses in extent. While the value of their vegetation is increasingly recognized it is unclear to what extent these systems can regenerate or resist the increasing environmental stressors associated with climate change, particularly heating & drying. The motivation of BIO-RED is to understand how these changes affect the ability of intact & regenerating ecosystems to deliver societal benefits. This requires addressing these key questions: (i) How resilient are old-growth & regenerating ecosystems to the key stressors expected from future environmental changes? (ii) Is the destruction a reversible process on time-scales relevant to human society? Thus, will vegetation recover to a similar state as the original and provide similar services? (iii) Will the increasingly hot climate affect the recovery of forests and will modified forests be more vulnerable to future environmental change than intact forests? Answering these questions is only possible with a sound understanding how these systems function and what their sensitivities are. To respond to this need, BIO-RED will apply a multi-scale approach to evaluate the relationships between functions, biodiversity, resilience and regeneration potential in Brazil's three largest biomes in the face of deforestation and climate change threats. Our objectives are to: (i) Determine the biome-wide relationships between target ecosystem functions and biodiversity based on data from the RAINFOR and associated vegetation census networks; (ii) Obtain a detailed mechanistic understanding of the link between biogeochemical cycling, plant nutrient use and species composition and diversity in primary and regenerating systems at the local scale in 3 study landscapes; (iii) Examine tree species' ecophysiological sensitivities to key climate-linked stressors - drought, heat & fire - via real-time monitoring of vegetation functioning and comprehensive trait assessments; (iv) Develop and apply a UAV ("drone")-based imaging spectroscopy platform to map canopy chemistry and functional diversity at tree, plot & landscape scales, and explore the relationships between ecosystem properties & functional diversity; (v) Establish the extent to which biome transitions are already occurring, including forest invasion into cerrado, using both permanent plots and satellite-based monitoring. (vi) Determine the ability of recovering ecosystems and ecosystem management to protect biodiversity & provide key ecosystem services in Brazilian biomes; BIO-RED builds on existing observational networks all led by PIs of this proposal: RAINFOR, GEM, ForestPlots.net (>500 old-growth forest plots), ECOFOR & BIOTA, and others contributed by Brazilian project partners. Most activities will be focused on 3 focal-landscapes, in W Pará (Amazon forest), E Mato Grosso (cerrado), & E São Paulo (Atlantic forest), each with a complex mosaic of old-growth & regenerating systems that is already well sampled by our plot infrastructure and so ideal for intensive work to probe processes & to scale-up via hyperspectral imaging. BIO-RED will improve understanding of the extent to which Brazilian forest & savanna are resisting climate extremes, the extent to which destruction is reversible, & the vulnerabilities of intact & modified vegetation to climate extremes. It will identify the factors that control resilience & recovery of biodiversity & provision of key ecosystem services to people. These will be used to inform ecosystem management & policy options such as REDD+, the Brazilian Forest Code, & Brazilian ecosystem recovery plans. We therefore expect to lay a stronger scientific basis for future regeneration & protection of these systems, and so to improve benefits for human society.

SUMMARY The Amazon is the most important biome of South America, harbouring extraordinarily high levels of biodiversity and providing important ecosystems services. This biome is particularly notable for evolving independently from fire and in a moist, warm climate. In recent decades, altered fire regimes and an increasingly hotter and drier climate has pushed this key biome towards ecological thresholds that will likely lead to major losses in biodiversity and ecosystem services. Similarly, the ecotonal forests at the Amazon-Cerrado transition are unique ecosystems in terms of form and function, but they may be the first to suffer large-scale tree mortality and species loss due to the combined effects of increased anthropogenic disturbance, altered fire regimes and a drier climate. Vulnerability of fire and droughts are closely intertwined in Amazonian and transitional forests because fires in this region only occur when there is water stress and a human ignition source. Thus, drought increases vulnerability to fire, but we do not yet understand the magnitude and spatial variation of these vulnerabilities. Once a forest burns there is immediate tree mortality, but recent evidence also shows a significant time-lagged mortality that can last for decades, becoming an important carbon source. However, the mechanistic processes that lead to time-lagged tree mortality in this myriad of forest ecosystems encompassing the Amazon biome and the Amazon-Cerrado transition are still poorly understood. We also lack knowledge on how these processes might vary spatially across the biome and its transition. A better understanding of the mechanisms that lead to tree mortality after fires and droughts is needed to design future policies that emphasise nature-based solutions including restoration and natural regeneration. This proposal presents a multi-level approach that aims at deciphering the mechanisms that underly vulnerability to fire and time-lagged post-fire mortality across the tropical forests in Amazon and Amazon-Cerrado transition. To achieve this aim, we will quantify fire vulnerability at three different scales and link them through an upscaling approach. First, we will identify the ecological mechanisms, reflected through functional traits, that explain why individuals and species die after fires occur. For this, we will focus on poorly understood traits that can be related to fire and/or hydraulic functioning. Second, at the community scale, we will examine how vegetation structure, community traits and microclimate affect the probability to burn, through an intensive characterisation of different vegetation types with multispectral and light detection and ranging (LIDAR) imagery. Third, we will use our our unique ground-dataset on functional traits, vegetation structure and moisture dynamics, and the latest state-of-art remotely sensed information on structure and water stress to predict the vulnerability of the Amazon forests and Amazon-Cerrado transitional forests. This information will be directly applicable for the detection of sensitive hotspots (areas particularly vulnerable to fire) through satellite products. We will deliver quantifiable early-warning metrics of ecosystem vulnerability to fire that can be mapped and incorporated into fire management policies. This is a revised version of a NERC proposal that was rejected with a score of 7 by the NERC Panel in July 2020, and we have carefully addressed the Panel's comments. Specifically, we have clarified the methodology and we have reformulated the hypotheses, so they address vulnerability to fire and not drought fire-interactions.