Tropical forests responses to a changing climate: a quest at the interface between trait-based ecology, forest dynamics and remote sensing

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The most pressing questions in ecology and ecosystems science today focus on how communities of organisms respond to global environmental changes. How is biodiversity affected by climate change? And, how does biodiversity influence ecosystem resilience to climate change? In terms of Earth system science, we need to understand and model how the terrestrial biosphere will respond (and already is responding) to atmospheric change, and whether there are dangerous thresholds or "tipping points" beyond which major biomes may not be able to recover.Nowhere is the challenge more urgent or more daunting than in the species-rich tropical forest and woody savanna biomes, which together are home to more than 50% of global diversity and over 60% of terrestrial productivity2. There is already mounting evidence that atmospheric change is having an effect on tropical forest productivity and tree composition3. This response may include a stimulation of productivity (caused perhaps through rising CO2), and/ or a degradation or dieback, caused perhaps by increased seasonality and increased frequency of extreme drought events, such as the two "once-a-century" droughts experienced by Amazonia in 2005 and 2010, and the intense El Niño-associated drought of 2015 that affected many tropical regions worldwide. However, we cannot adequately understand or simulate such responses with current ecosystem model approaches that cannot capture the high diversity and the quasi-continuum nature of plant ecosystem function in the species-rich tropics. Neglect of functional biodiversity can greatly oversimplify and over-sensitise the simulated response of an ecosystem to an environmental disturbance. Some of the key challenges we face revolve around how can we track changes in the species composition and function of tropical ecosystems as they respond to global change. The use of plant functional traits provides a potential way forward by simplifying tropical biodiversity into a few key axes of functional variation. This project will conduct the first analysis of long term functional change in intact tropical forests and woody savannas. Firstly, it will explore how tree communities and their functional characteristics have shifted over time under a changing climate, by combining long-term forest inventory data form across the tropics with newly collected and collated data on tropical tree functional traits. It will also examine how the patterns of traits shifts vary across bioclimatic regions, which encompass different elevation, latitude and climatic conditions, to gain greater insight into how soils and past climate variation influence current sensitivity to climate change. Next it will examine whether the associated shifts in ecosystem species composition are sufficiently rapid to keep pace with the observed rates of climate change. Finally, it will explore the potential of monitor trait patterns at scale through the use of the newest generation of satellite multispectral data from the European Space Agency Sentinel-2 Copernicus mission.This project will bring a step-change in i) our understanding of how climatic changes drive traits distributions, ii) our ability to predict functional trait composition by remote sensing, iii) will impact the way how we track the progress towards, an inform sections of, international policy such as the Aichi Biodiversity Targets (Goal A and C), Sustainable Development Goals (combating climate change and its impacts), the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and iv) will foster a transition from a descriptive to a more predictive trait ecology.