Deforestation and marginalization of rural poor continues in Brazil and Bolivia despite investment in institutional change, forest regulation, improving land management practices and economic development. Previous approaches to equitable management of forest ecosystems in the Amazon tended to offer very narrow formalised solutions, lacked structure and coherence, were too insular and lacked broader international perspective and expertise. The proposed project will address these gaps by providing a holistic and inter-disciplinary approach to understanding the links between the causes, mechanisms and the effects of deforestation on poverty at the agricultural frontier in three case study areas in Bolivia and Brazil. The problem of making the benefits of forest ecosystems available equitably to the disadvantaged people is one of the top priority policy issues identified in the Millenium Ecosystem Assessment (2005). However, environmental governance in the Amazon tends to lack engagement with forest dependent poor, so that some ecosystem management initiatives restrict poor people's access to resources and reduce their anti-poverty capabilities. The proposed project attempts to rectify this problem by giving the voice to the rural poor in the Amazon frontier, reconnecting them with the regional policy makers and linking them into broader research networks to develop Southern-led solutions to the problems of deforestation and poverty. Through the series of workshops, pilot studies and user-engagement events the proposed project exposes dynamism of deforestation and its effects on poverty in the frontier areas as well as suggests institutional changes necessary for equitable forest ecosystems management in the Amazon. It will attend to three key areas: 1. Understanding concerns over, experiences of and reactions to deforestation by the forest dependent poor The project will give voice to the forest dependent poor to articulate their concerns over forest degradation and deforestation and to incorporate their perspectives on poverty and poverty alleviation into the development of pathways to sustaining ecosystem services. 2. Developing holistic, interdisciplinary approaches to poverty alleviation through sustainable forestry The proposed project will address fragmentation of existing mechanisms governing ecosystem management and tackling poverty of the people affected by deforestation by bringing together forest dependent poor, policy-makers, governing bodies, and research institutions involved in rural development. It will evaluate existing policies reducing environmental vulnerability, address the lack of capacity and explore the potential for more effective inter-agency work to avoid policy conflicts and duplication of development efforts. 3. Developing international knowledge networks to facilitate equitable forest management Through a series of workshops and pilot studies the project will develop southern-led solutions to deforestation and the alleviation of poverty. It will enable knowledge transfer, research networking and cross-agency learning for the actors at local, national and international levels involved in sustainable forest management in the Amazon.

This research partnership will build and strengthen scientific collaboration between UK and Brazilian researchers. Our team will work together to develop new, innovative research in order to reduce the vulnerability of Amazonian cities to extreme climatic events, such as floods and droughts. We hope that this research enables decision-makers in Brazil to identify those cities that need humanitarian assistance most during climate emergencies, and also build long-term resilience (capacity to absorb these shocks) to floods and droughts. Our team members come from various academic disciplines, including statistics, health science, economics, environmental social science, and spatial modelling. We will use secondary data sources to examine how adaptive capacity, local institutions and natural hazard exposure (the occurrence of droughts and floods) influence the negative impacts of these climate events on the well-being of people living in Amazonian cities. We are also interested in how extreme climatic events may influence food prices in these cities, which has implications for the affordability of food for the poorest city-dwellers. Our network also involves local citizens, and we will work with a range of community members in our focal cities in order to make sure that are research is locally-relevant and useful. Finally, we are investing significant effort in improving career opportunities for Amazonian scientists, and will achieve this through UK-Brazil researcher exchange, and workshops to train Masters and PhD students in the UK and Brazil.

We propose an international network to explore this key knowledge gap in understanding the effects of pests and pathogens in accelerating tropical rainforest tree mortality during drought. The project will deliver an integrated and focused anlaysis, using expertise in plant physiology, forest ecology and microbial and insect ecology. It will also make use of the unique leverage of the world's only long-term drought experiment network in tropical forests. We will use field-based workshops at two current tropical forest drought experiments, in Australia and Brazil, to bring together experts in plant function, the effects of pest and pathogen ('biotic') attack on woody tissue, and vegetation modelling. New ground-based and remotely-sensed measurements will be examined to test for relationships between measures of biotic attack and metrics of plant function during experimental drought. We will compare responses in different tree size classes, tree species groups, and at the level of the forest ecosystem (large experimental plot treatment). The outcome will be new insights into the causes of tropical rainforest tree death from drought, in relation to plant physiology and insect or microbial attack. This insight will be delivered in the form of new data, new scientfic articles and information that can be used by vegetation modellers to predict the effects of drought on tropical forests in the future. The group of experts built using these funds will form a pre-eminent multi-disciplinary consortium in the subject area, capable of advancing the subject into the future for the benefit of the science, interested environmental policy makers and university educators.

The Southern Amazon faces the greatest climatic threat of all Amazon regions. This region is drier and warmer than 'core' areas of the Amazon and has been subject to the most pronounced drying and warming trends. It is also the region of the Amazon where increases in tree mortality have been most marked and where atmospheric measurements suggest forests are no longer acting as a carbon sink but as a net source of carbon to the atmosphere. Given that Southern Amazon is at the front line of the Amazon's battle against climate change, it is essential that we better understand how resistant its forest species are to climate stress. In Lethal Psi, we will construct a new 1-hectare drought experiment to better understand the physiological survival limits of southern Amazon trees. It has become increasingly clear that the process of hydraulic failure plays an important role in drought-induced tree mortality. Water is transported from the soils to the canopy under tension. As drought ensues and the soil dries, the tension in the xylem vessels that transport water intensifies and this can lead to the formation of air bubbles (embolism) in xylem vessels, disrupting water transport to the canopy and ultimately resulting in tree death. While this process is understood in general terms, one critical current knowledge gap is that we don't know the thresholds in embolism formation that result in the death of tropical trees. This lack of understanding of the physiological thresholds that result in death constitutes a key uncertainty for accurately modelling tree mortality under climate change. Determining the hydraulic thresholds of tree death is not an easy task and requires monitoring tree hydraulic status up to the point of death. In Lethal Psi, we track key indicators of hydraulic function (e.g. leaf water potentials and sap flux) from the beginning of our imposed drought all the way to the death of the tree to quantify how loss of xylem conductance translates into mortality risk. While other drought experiments have been set up in Amazonia, these did not monitor embolism status before and during the mortality process and were thus unable to provide insights into physiological thresholds of survival. Up to now, drought experiments have only been set up northeastern Amazonia, where annual rainfall is almost twice that of our study site and where changes in climate have been much less pronounced than in southern Amazonia. Given their ecotonal nature and the rapid climate change experienced in southern Amazonia, we expect that trees in this region are much closer to their climatic limits and will experience much more accentuated mortality under imposed drought than observed in northeastern experiments. Ultimately, we plan to use the newly acquired field data to develop improved mortality functions that we will apply more broadly across southern Amazonia to better predict drought mortality risk of this critically important region. This will be done by updating a unique trait-based model specifically developed to simulate Amazon forests and their responses to environmental change.

This project addresses a key gap in understanding how tropical forests respond to drought across scales, from organ to tree and forest ecosystem. It will drive extended impact in new monitoring capability using satellite data, in advanced land surface modelling, and in drought risk mitigation planning, by engaging related stakeholders through 'Science & Impact' workshops. We propose the powerful combination of a unique large-scale field experiment in Amazônia together with detailed ecophysiological and new tower-based radar measurements to deliver new insights into drought responses across scales, both during drought, and importantly, during post-drought recovery. Water availability plays a dominant role in the global carbon cycle, with a large influence from Amazônia. However, our ability to predict the effects of changing water availability is substantially constrained by limited understanding of the ecological processes occurring in response to drought, particularly in tropical forests. These responses occur across different scales, from leaf to tree to forest ecosystem, with very large impacts on the carbon cycle observed regionally and globally. Understanding drought responses of tropical forests has proved challenging for several reasons: a lack of ecophysiological analysis at the right scales; limited capacity to deliver continuous monitoring of mechanistically-informed water stress responses at large scale, eg using satellites; and limited understanding of the ecological processes comprising drought stress and its consequences. We ask: How does drought stress affect whole-tree function, and can critical processes such as transpiration and growth recover after drought in tropical forests? Does drought stress leave a long-term legacy by limiting growth potential and by increasing the risk of possible tree mortality from future drought? And critically, how do the effects of drought on tree function affect performance at the scale of many trees, ie, that of a tropical forest? Multi-scale measurements are needed to address these questions. A combination of focused ecophysiological measurement with new tower-based radar (microwave) observations has the potential to enable large advances in understanding, scaling from tree to forest and region. This project will combine the world's only long-term drought experiment at hectare scale in tropical forest, which we have run for the past twenty years, with new radar sensors. We will use tower-based radar measurements to detect changes in vegetation water content at the scale of the experiment. This will provide higher resolution detection and mechanistic insight than was previously possible using satellite radars, and allow us to connect radar and plant ecophysiological data. Our specific hypotheses address: the links between organ-, tree- and ecosystem-scale responses to drought, and after drought; how these data advance our understanding of forest function and the risk to function and survival; and how this understanding can be used to advance satellite monitoring of drought impacts, and its wider use. In summary, we have three main goals: i) To use our ecosystem-scale drought experiment in Amazônian forest to quantify and understand the effects of drought at multiple scales, using plant physiology and tower-based radar (microwave) measurements. ii) To understand post-drought legacy effects on forest resilience by using the control enabled by our experiment to halt the drought and monitor recovery processes, and the outcomes for growth and survival. iii) To use (i) and (ii) to advance large-scale satellite detection capability in tropical forests for improved biomass and drought-response monitoring. We will lead two 'Science and Impact' workshops to rapidly multiply outcomes of the work by helping to improve prediction of land-atmosphere interactions using vegetation models, and better early-warning capability for land-use planning.