The overall aim of this project is to determine and communicate the risk of significant change to the Amazon rainforest caused by anthropogenic disturbance and climate change. We will address a fundamental issue of our time, on the likelihood of Amazon rainforest dieback in the 21st century and identify regions that are most susceptible. We will combine this new knowledge with policies and scenarios developed by key stakeholders to co-design a Safe-Operating-Space for Amazonia. To address the iconic issue of Amazon dieback we will advance new ecological understanding of how forests grow, decline and recover following disturbance from climate extremes, forest fire and deforestation and their interaction in the context of 21st Century global warming. We will build novel datasets using a new forest plot network, drones and satellites to produce near-real-time maps of the risk to forests from climate, and track individual large-tree mortality across the basin. Together this information will be used in mathematical models to help estimate the risk of future forest dieback. We will join this work with models used to predict the effects of land use (forest conversion, degradation) on forest function, and the ecosystem services these forests provide to humanity. The outputs will enable us to deliver new information to policy makers regarding future options for land use, helping them to build optimal land use pathways that minimise the risks that may arise out of large-scale forest loss or dysfunction in Amazonia. The Amazon forest plays a vital role in the world's climate. In addition, by annually absorbing 5-10% of human-related CO2 emissions via vegetation growth, the region acts as a large brake on climate change. Climate extremes (eg drought), forest fires and deforestation reverse this process, causing net emissions to the atmosphere. If this were to happen on a large enough scale, via increased forest loss or increased rates of climate change - or their interaction - the resulting positive effect on global CO2 and climate change, would make the already-challenging Paris climate targets virtually impossible. In short, climate change, forest fires and deforestation have been identified as major intensifying and interacting threats to Amazonia. A substantive loss of Amazonian forest, also known as "Amazon dieback", would have huge negative consequences for human well-being, biodiversity, biogeochemical cycling, and regional and global climate. However, the level of global climate change combined with human disturbance that could trigger large-scale dieback is not known. Climate change is predicted to become more intense in the region alongside increases in human-driven deforestation and forest degradation (e.g fires, logging). Their impacts are poorly understood because of a lack of data, and because models cannot currently represent the key processes well enough. We have gathered leading UK and S American scientists in the fields of ecology, ecophysiology, Earth observation (using satellites) and the mathematical modelling of vegetation growth, land-use and climate as applied to Amazonia. We are uniquely positioned to make a step-change in understanding the combined effects of climate stress and human disturbance on Amazonia. Our measurements will build new knowledge about intact and disturbed forests, their stability and the physiology driving their stress responses. These knowledge advances will enable new modelling of forest-climate-land-use interactions which we will use to inform policymakers. We will engage with stakeholders from state to international levels to co-develop land-use scenarios that minimise risk in future climate and forest ecosystem services. Overall, we propose multiple large and integrated advances in empirical and modelling studies of the forests of Amazonia, and will build a science-policy dialogue that delivers significant impact locally, regionally and globally.

Wildfires are becoming the new normal across Amazonia. Deforestation is transforming the region at a rate of around 10,000 square km/year (half the area of Wales), and now the area degraded annually -forest logged and burned but not cut down-is greater than the area deforested. Fire has historically been rare in Amazonia, meaning that the forests are not adapted to fire and the trees often die from fires - releasing carbon (C) back to the atmosphere and amplifying global climate change. Burning of tropical forests is already releasing more climate-warming carbon dioxide than fossil fuel burning in the whole of Europe. Trees in Amazonia contain around 7x more C than humans are releasing every year, and soils contain the same amount again, so it is vital to understand what is happening to this C and minimize emissions. As vegetation sheds its leaves, branches, and roots, or dies, some of the C released remains in the soil, and some is later decomposed and released back to the atmosphere. Carbon exists in the soil in many different forms, from new inputs from decomposing plant material to ancient C formed over millennia. Burning adds pyrogenic carbon (PyC) to the soil, a partially burnt form of C that is resistant to decomposition and could make the soil more fertile. Because soil C takes a long time to form, its conservation is particularly important. Despite the widespread increase in fire in Amazonia, there have been few measurements of soil C fractions and dynamics in burned areas - most have focussed on natural forests. Burned forests will have different composition, forest structure, and C dynamics. Understanding how different soil C fractions are formed and lost is crucial to understand how fire and climate change affect C storage. We propose to make major advances in understanding fire impacts, including the processes that affect the type and quantifies of soil C formed, and how C gains/losses vary over time, with soil type, and climate. We will combine new measurements with innovative modelling to inform land management strategies and C budgets. We have already collected data from across Amazonia in intact forests that have not recently burned. Crucially our project will collect a new, comprehensive dataset from human-modified forests, including logged, burned and abandoned land. We will use an approach known as a chronosequence, where we take samples at sites that were burnt at different times in the past, so we can see how the soil C has changed after e.g. 1 year, 2 years, or up to 20 years after a fire. This will then be used to develop a state-of-the-art land surface model, JULES, which forms part of the UK Earth System Model. At our sample sites, we will evaluate how different burn severities affect soil C, both in surface and deep soils, and how these change over time post-burning and with soil, climate, and land-use such as logging. At 3 focal sites, we will take detailed measurements of the decomposition rate of the C over 4 years, comparing measurements with different land-use, burn severity and wet vs dry seasons. Knowing what forms C takes after a fire and how fast it decomposes under different conditions will enable us to build these processes into the JULES model. We will model PyC globally for the first time and make projections of land C changes in Amazonia over the next ~40-60 years under different management practices. As well as transforming scientific understanding of post-fire soil C and its resilience to climate and management, our project will inform socio-environmental planning for sustainable resource use to conserve soil C. We will work with regional partners, fire managers, state and national policymakers to integrate our findings into decision-making to minimise negative fire impacts. Due to the Amazon Basin-scale of our work, these strategies are a crucial step to limit the risk of large-scale loss of soil C.