The requirement to feed a rapidly increasingly human population whilst maintaining ecosystem services and reducing biodiversity losses has led to an urgent need to design more sustainable agricultural landscapes. This is particularly relevant in SE Asia where oil palm plantations are replacing hyper-diverse tropical rainforest. Current policies for the sustainable cultivation of oil palm (an important source of edible vegetable oil) require the retention of rainforest fragments within plantations. However, the assumption that these forest fragments can continue to support high biodiversity, maintain their viability, and regenerate over time has not previously been tested. Thus one of the primary criteria for sustainability is essentially untested, and forms the basis of this proposal. SE Asian rainforests are unique in being dominated by Dipterocarpaceae trees which reproduce irregularly (at intervals from 1 to many years) but synchronously in mass fruiting events. One of these unpredictable mass fruiting events has recently been initiated on Borneo, and provides a rare opportunity to study dipterocarp reproduction in rainforest fragments. Dipterocarp trees are a vital component of rainforest ecosystems in SE Asia, and hence any changes that affect dipterocarps are likely to have considerable knock-on impacts for rainforest biodiversity. Our recent data show an absence of dipterocarp seedlings in small forest fragments even when mature dipterocarps are present, raising a serious concern of reproductive failure of dipterocarps in fragments. The recently-initiated mass fruiting event provides us with an opportunity to explore potential mechanisms leading to reproductive failure and/or recruitment failure in forest remnants. The main objective of this project is to: (1) examine how forest fragmentation affects dipterocarp reproduction, (2) relate reproductive rates to biotic and abiotic changes arising from forest fragmentation (altered microclimates, habitat quality, predation), and (3) assess whether dipterocarp species are equally sensitive to impacts of forest fragmentation. The proposed work will provide the first investigation of the long-term viability of forest remnants in tropical agricultural landscapes. The project will address fundamental questions about reproduction in dipterocarp trees under altered abiotic and biotic conditions, as well as producing results of considerable practical value for policy makers. It will form the basis for new research in future focussed on understanding the impacts of habitat degradation and fragmentation on biodiversity, and contribute to scientific evidence to inform the debate on developing effective conservation and sustainability strategies.

The over-arching goal of this project is to test the unanswered question of whether the functioning of tropical forest ecosystems-such as how much biomass they produce-depends on how diverse they are and therefore whether replanting degraded forests with diverse mixtures of species can accelerate their recovery and help fund replanting costs through carbon credits. Tropical forests are being lost all over the world and of the remaining area more is degraded secondary forest than undisturbed old growth. This degradation occurs largely through selective logging which has negative effects of the functioning of the forest (e.g. how productive it is and how much carbon it stores) as well as on its biodiversity. This is important because work outside of the tropics in ecosystems like temperate grasslands has demonstrated a positive relationship between biodiversity and a range of ecosystem functions, including primary productivity. However, the challenges of scientific research in the tropics mean we have much less evidence of whether there is a positive relationship between levels of tree diversity and aboveground biomass production in tropical forest ecosystems. Indeed, some ecological theory suggests that species in these ecosystems are so similar ecologically that many species could be lost with little or no impact on how these ecosystems function. Twenty years ago, we started a collaboration with local foresters, conservationists and scientists in Sabah (Malaysian Borneo) to set up a long-term experiment to test whether there is a relationship between biodiversity and ecosystem functioning in these tropical forest ecosystems. The project, the Sabah Biodiversity Experiment, is one of the world's largest ecological experiments, making it of particular relevance to real-world efforts to restore and sustainably manage tropical forests. The experiment has adopted the existing forest restoration activity of 'enrichment planting' to plant more than 100,000 seedlings of native tree species across an area of 500 hectares of logged forest, allowing the recovery rates of naturally regenerating control plots to be robustly compared with those planted with different diversities (1, 4 or 16 species) and mixtures of tree species. We will assess restoration progress relative to nearby old growth forest, especially the neighbouring undisturbed area where we have repeatedly mapped and measured every tree within a 50-hectare area (the Danum Valley ForestGeo Plot) as part of a global network to monitor forest health. The large size of our research plots means they are difficult to repeatedly monitor in fine detail using traditional field methods. We will therefore combine targeted field sampling with cutting-edge remote sensing technologies to explore how tree enrichment planting has shaped the recovery of canopy structure, aboveground carbon stocks and plant diversity across hundreds of hectares of degraded forest. Our project will take advantage of existing data acquired for our study sites using two complementary technologies: LiDAR and satellite remote sensing. Airborne LiDAR uses a laser mounted on an airplane or helicopter to precisely measure the height of the vegetation and reconstruct the 3D structure of the forest canopy and underlying terrain in exquisite detail, allowing forest carbon stocks to be accurately mapped across entire landscapes. To get a more detailed and longer-term picture, the project will also use freely available satellite timeseries data (Sentinel 1-2, Landsat 8 and PlanetScope imagery) to map annual changes in forest aboveground carbon stocks (using Google Earth Engine). In the final phase we will work with local partners including the Sabah Forestry Department on a cost-benefit analysis of forest restoration and communicate these results so that they can inform their local and regional management policies for the conservation and restoration of forests and the carbon that they store.

Tropical forests support over two-thirds of the world's terrestrial biodiversity. However, between 35% and 50% of tropical forests have already been degraded, and the rate of deforestation continues to increase. Secondary forests, plantations and other human-modified habitats now dominate tropical landscapes, leading to concerns that human degradation of these landscapes will elevate greenhouse gas emissions and jeopardise ecosystem services at local, regional and global scales. The area of protected forests is unlikely to increase greatly in the future, so the persistence of tropical biodiversity and the important biogeochemical cycles and ecosystem services associated with it will depend to a large extent on the way we treat the wider tropical landscape. The Human Modified Tropical Forests programme seeks to 'significantly improve our understanding of the links between biodiversity and biogeochemical cycles in tropical forests' through 'integrated observations and modelling linked to gradients in forest modification'. To contribute towards this goal our consortium will use surveys along a modification gradient within the SAFE landscape in Sabah (Malaysian Borneo) to detect patterns, combined with manipulative field experiments to gain a mechanistic understanding of biodiversity-function linkages. We will assess links between above- and belowground components of tropical biodiversity and investigate the extent to which different elements of biodiversity (e.g. species of conservation concern) are associated with measures of ecosystem function (decomposition processes and biogeochemical cycles). We will then upscale from the experimental sites to the landscape-scale to generate spatial layers of ecosystem function, biodiversity, and greenhouse gas fluxes to inform policy scenario modeling. Our work will thus (1) characterise soil microbial function and measuring associated biogeochemical fluxes; (2) Experimentally test the links between aboveground biodiversity and soil function; (3) Build and add to existing datasets for bird and mammals, and explore correlations between ecosystem functioning and the distribution of species of conservation concern; and (4) Explore policy scenarios for optimising biodiversity and function protection.

Coral reefs are the most diverse marine ecosystems on Earth and provide enormous economic value for hundreds of millions of people including fisheries, tourism, and coastal protection. However, these benefits are threatened by the rapid decline of coral reefs resulting from accelerating human impacts on local to global scales. Confronting this reef crisis with limited resources requires prioritisation of protection actions, and many researchers are now turning to reef ecosystems living outside of typical shallow, clear-water habitats as critical priorities for additional research. There is new evidence that these so-called marginal reefs living in turbid or deeper water can be more resilient to bleaching, changes in water quality, and other impacts. Increased bleaching resilience might result from sediments in the water that limit UV stress, or because the corals may be more readily able to take advantage of food sources in the plankton. Thus, marginal reefs potentially serve as refugia for resilient corals, and could be critical for the future recovery of declining clear-water reefs. However, most studies of marginal reefs have focused on contemporary (and in a few cases historical) assessments from sites on the Great Barrier Reef (GBR) and the Caribbean. New datasets from different regions are needed to capture the full range of modern human impacts (especially in areas of the most diverse coral development), and we also need data that spans the timescales (centuries to millennia) necessary to capture coral ecological adaptation and migration within marginal settings. In this context, recent discoveries of exceptionally preserved fossils from the Coral Triangle (CT) region of Southeast Asia provide a unique opportunity to integrate present-day ecological data with information from the geological record to document the evolutionary and ecological history of turbid water reefs in the modern-day global biodiversity hotspot. There is an urgent need for more information on the diversity, structure, and functioning of marginal reefs in the CT in order to help develop management strategies they continue to respond to human impacts. The long-term temporal scope of our study is thus significant. A growing body of research aims to describe the composition, distribution, and genetic structure of potential present-day reef refugia and we will add data from the fossil record into these analyses. There is a compelling case to do this because reef resilience is likely to be shaped by long-term processes with deep roots in evolutionary history. We will assess the dual role of marginal reefs in the CT as both cradles and refugia of diversity. Key research questions include: 1) has coral diversity of marginal ecosystems changed through time? 2) how have reef communities responded to environmental changes on regional or global scales? 3) how has reef functioning in marginal settings changed and what have been the consequences for reef-associated biota? 4) how easy has it been for reef-corals to move from marginal to clear-water reefs during the evolution of the biodiversity hotspot, and 5) what could be the consequences for the modern biota if clear water habitats become increasingly inhospitable? To address these questions we will produce new comprehensive datasets of species occurrences, abundances, morphological traits, ecological data, and environments that cover 30 million years of reef history of the CT. With this resource, we will provide rigorous answers to long-debated issues by applying new tools for molecular systematics, geochemistry, and evolutionary patterns to modern reefs and an extensive and well-sampled fossil record. Ultimately, we will be able to reveal the murky history of marginal reefs in the CT and better understand the potential future trajectories of change for coral reefs in the CT and in other regions that depend on coral reefs for their economic and ecological value.

Anthropogenic disturbance and land-use change in the tropics is leading to irrevocable changes in biodiversity and substantial shifts in ecosystem biogeochemistry. Yet, we still have a poor understanding of how human-driven changes in biodiversity feed back to alter biogeochemical processes. This knowledge gap substantially restricts our ability to model and predict the response of tropical ecosystems to current and future environmental change. There are a number of critical challenges to our understanding of how changes in biodiversity may alter ecosystem processes in the tropics; namely: (i) how the high taxonomic diversity of the tropics is linked to ecosystem functioning, (ii) how changes in the interactions among trophic levels and taxonomic groups following disturbance impacts upon functional diversity and biogeochemistry, and (iii) how plot-level measurements can be used to scale to whole landscapes. We have formed a consortium to address these critical challenges to launch a large-scale, replicated, and fully integrated study that brings together a multi-disciplinary team with the skills and expertise to study the necessary taxonomic and trophic groups, different biogeochemical processes, and the complex interactions amongst them. To understand and quantify the effects of land-use change on the activity of focal biodiversity groups and how this impacts biogeochemistry, we will: (i) analyse pre-existing data on distributions of focal biodiversity groups; (ii) sample the landscape-scale treatments at the Stability of Altered Forest Ecosystems (SAFE) Project site (treatments include forest degradation, fragmentation, oil palm conversion) and key auxiliary sites (Maliau Basin - old growth on infertile soils, Lambir Hills - old growth on fertile soils, Sabah Biodiversity Experiment - rehabilitated forest, INFAPRO-FACE - rehabilitated forest); and (iii) implement new experiments that manipulate key components of biodiversity and pathways of belowground carbon flux. The manipulations will focus on trees and lianas, mycorrhizal fungi, termites and ants, because these organisms are the likely agents of change for biogeochemical cycling in human-modified tropical forests. We will use a combination of cutting-edge techniques to test how these target groups of organisms interact each other to affect biogeochemical cycling. We will additionally collate and analyse archived data on other taxa, including vertebrates of conservation concern. The key unifying concept is the recognition that so-called 'functional traits' play a key role in linking taxonomic diversity to ecosystem function. We will focus on identifying key functional traits associated with plants, and how they vary in abundance along the disturbance gradient at SAFE. In particular, we propose that leaf functional traits (e.g. physical and chemical recalcitrance, nitrogen content, etc.) play a pivotal role in determining key ecosystem processes and also strongly influence atmospheric composition. Critically, cutting-edge airborne remote sensing techniques suggest it is possible to map leaf functional traits, chemistry and physiology at landscape-scales, and so we will use these novel airborne methods to quantify landscape-scale patterns of forest degradation, canopy structure, biogeochemical cycling and tree distributions. Process-based mathematical models will then be linked to the remote sensing imagery and ground-based measurements of functional diversity and biogeochemical cycling to upscale our findings over disturbance gradients.