The ecosystems of the dry tropics are in flux: the savannas, woodlands and dry forests that together cover a greater area of the globe than rainforests are both a source of carbon emissions due to deforestation and forest degradation, and also a sink due to the enhanced growth of trees. However, both of these processes are poorly understood, in terms of their magnitude and causes, and the net carbon balance and its future remain unclear. This gap in knowledge arises because we do not have a systematic network of observations of vegetation change in the dry tropics, and thus have not, until now, been able to use observations of how things are changing to understand the processes involved and to test key theories. Satellite remote sensing, combined with ground measurements, offers the ideal way to overcome these challenges, as it can provide regular, consistent monitoring at relatively low cost. However, most ecosystems in the dry tropics, especially savannas, comprise a mixture of grass and trees, and many optical remote sensing approaches (akin to enhanced versions of the sensors on digital cameras) struggle to distinguish changes between the two. Long wavelength radar remote sensing avoids this problem as it is insensitive to the presence of leaves or grass, and also is not affected by clouds, smoke or the angle of the sun, all of which complicate optical remote sensing. Radar remote sensing is therefore ideal to monitor tree biomass in the dry tropics. We have successfully demonstrated that such data can be used to accurately map woody biomass change for all 5 million sq km of southern Africa. In SECO we will create a network of over 600 field plots to understand how the vegetation of the dry tropics is changing. and complement this with radar remote sensing to quantify how the carbon cycle of the dry tropics has changed over the last 15 years. This will provide the first estimates of key carbon fluxes across all of the dry tropics, including the amount of carbon being released by forest degradation and deforestation and how much carbon is being taken up by the intact vegetation in the region. By understanding where these processes are happening, we will improve our knowledge of the processes involved. W will use these new data to improve the way we model the carbon cycle of the dry tropics, and test key theories. The improved understanding, formalised into a model, will be used to examine how the dry tropics will respond to climate change, land use change and the effects of increasing atmospheric CO2. We will then be able to understand whether the vegetation of the dry tropics will mitigate or exacerbate climate change, and we will learn what we need to do to maintain the structure of the dry tropics and preserve its biodiversity. Overall, SECO will allow us to understand how the vegetation of the dry tropics is changing, and the implications of this for the global carbon cycle, the ecology of savannas and dry forests, and efforts to reduce climate change. The data we create, and the analyses we conduct will be useful to other researchers developing methods to monitor vegetation from satellites, and also to those who model the response of different ecosystems to climate and other changes. Forest managers, ecologists and development practitioners can use the data to understand which parts of the world's savannas and dry forests are changing most, and how these changes might be managed to avoid negative impacts that threaten biodiversity and the livelihoods of the 1 billion, mostly poor, rural people who live in this region.

Latin American forests cover a very large latitudinal and climate gradient extending from the tropics to Southern hemisphere high latitudes. The continent therefore hosts a large variety of forest types including the Amazon - the world's largest tropical forest - as well as the diverse Atlantic forests concentrated along the coast, temperate forests in Chile and Argentina as well as the cold rainforests of Valdivia and the Nothofagus forests of Patagonia. These forests are global epicentres of biological diversity and include several tropical and extra-tropical biodiversity hotspots. For example, the Amazon rainforest is home to ~10% of terrestrial plant and animal species and store a large fraction of global organic carbon. hotspots. Some of these Latin American forests still cover a large fraction of their original (pre-colombian) extent: the Amazon still covers approximately 5 Million km2, which is 80% of its original area. However, others, such as the Atlantic forest, have nearly disappeared and are now heavily fragmented. Temperate forests have also shrunk, despite efforts to halt further reduction. However, economic development, population rises and the growth in global drivers of environmental change mean that all forests now face strong anthropogenic pressures. Locally stressors generally result from ongoing development, selective logging, the hunting of larger birds and mammals, over-exploitation of key forest resources such as valuable palm fruits, mining, and/or forest conversion for agricultural use. Global environmental drivers stem from the world's warming climate. Yet it is not clear how these local pressures and changing environmental conditions will alter the composition of Latin American forests, and whether there are thresholds between human impacts - such as the lack of dispersers in heavily fragmented forest landscapes or climate conditions exceeding limits of species tolerance - and the community level responses of forest plants. We aim to investigate this, supporting the development of strategies that can preserve the diversity of these forests and their functioning. We achieve this by investigating the relationships between diversity and functioning of these forests; exploring whether there are thresholds in functioning resulting both from pressures of forest use and changing climate; by experimentally testing responses; and by generalizing predictive capability to large scales. ARBOLES aims to achieve these goals by integrating established forest inventory approaches with cutting-edge functional trait, genomics, experimental and remote sensing approaches. Our approach involves combining forest plots with plant traits, which will enable us to characterize state and shifts over time in the face of local human disturbance and changing climate and atmospheric composition. We will focus on traits along the following axes: (i) life-history strategies measuring investment in structure (like wood density, leaf mass per area, maximum height), (ii) investment in productive organs (like leaf nutrients), (iii) investment in reproductive organs, (iv) tolerance to water stress and heat stress. The work is being conducted in collaboration with research groups in Argentina, Brazil, Chile and Peru - and will provide a first cross-continent assessment of how humans are influencing Latin American forests.