How does global land-use change reshape ecological assemblages over time?

Terrestrial biodiversity is declining globally because of human impacts, of which land-use change has so far been the most important. When people change how land is used, many of the species originally present decline or disappear from the area, while others previously absent become established. Although some species are affected immediately, others might only respond later as the consequences of the land-use change ripple through the ecosystem. Such delayed or protracted responses, which we term 'biotic lag', have largely been ignored in large-scale models so far. Another shortcoming of much previous work is that it has focused on numbers of species, rather than what they do. Because 'winners' from the change are likely to be ecologically different from 'losers', the land-use change impacts how the assemblage functions, as well as how many species it contains. Understanding how - and how quickly - land-use change affects local assemblages is crucial for supporting better land-use decisions in the decades to come, as people try to strike the balance between short-term needs for products from ecosystems and the longer-term need for sustainability.

The most obvious way to assess the global effects of land-use change on local ecological communities would be to have monitored how land use and the community have changed over a large, representative set of sites over many decades. The sites have to be representative to avoid a biased result, and the long time scale is needed because the responses can unfold over many years. Because there is no such set of sites, less direct approaches are needed. We are planning to scour the ecological literature for comparisons of communities before and after land-use change. We can correct for bias because we have estimates of how common different changes in land use have been; and we will model how responses change over time after a land-use change so that we can use longer-term and shorter-term studies alike. There are many hundreds of suitable studies, and we will ask the researchers who produced them to share their data with us; we will then make them available to everyone at the end of the project.

We will combine data on species' abundances before and after the land-use change with information about their ecological roles, to reveal how - and how quickly - changing land use affects the relative abundances of the various species and the ecological structure and function of the community. Does conversion of natural habitats to agriculture tend to favour smaller species over large ones, for instance, and if so how quickly? Is metabolism faster in more human-dominated land uses? These analyses will require new compilations of trait data for several ecologically important and highly diverse arthropod groups; to produce these, we will make use of the expertise, collections and library of the Natural History Museum.

In an earlier NERC-funded project (PREDICTS: www.predicts.org.uk), we have already compiled over 500 data sets - provided by over 300 different researchers - that compared otherwise-matched sites where land use differed. The PREDICTS database has amassed over 2,000,000 records, from over 18,000 sites in 88 countries. The database contains more than 1% as many species as have been formally described. Our analyses of this unprecedentedly large and representative data set indicates that land-use change has had a marked global impact on average local diversity. However, because PREDICTS' data sets are spatial rather than temporal comparisons, they are not well-suited to analysing the dynamics of how assemblages respond to land-use change. More fundamentally, PREDICTS' assumption that spatial comparisons are an adequate substitute for temporal data now needs testing. This proposal will deliver the necessary tests, as well as producing the most comprehensive picture of how land-use change reshapes ecological assemblages through time.

We have identified three major beneficiaries from our proposal outside of academia, as follows:

1. International science-policy organisations and processes. Outputs from our empirical models have the potential to inform international agreements and processes, such as the Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services (IPBES) and the Group on Earth Observations Biodiversity Observation Network (GEO BON). IPBES's rapid assessment of scenarios and modelling of biodiversity and ecosystem services requires information on how to model impacts of drivers of biodiversity and ecosystem services. We will liaise directly with this IPBES deliverable through project partners Prof Simon Ferrier & Dr Jörn Scharlemann. GEO BON's modelling working group (WG7) has set as its top priority "Global estimation of change in retention of terrestrial biodiversity as a function of observed change in habitat condition and climate", while its third priority is "Global projection of change in retention and protection of terrestrial biodiversity under future scenarios of land use and climate." We will liaise directly with the GEO BON working group, through project partners Prof Simon Ferrier and Dr Jörn Scharlemann, and will also liaise with UNEP's next Global Environment Outlook (GEO6) through Dr Neil Burgess (Consultant, and Head of Programme, Science, at UNEP-WCMC); we will discuss with both processes to ensure that the models we run have maximum applicability. Our databases of before-and-after comparisons and functional trait data will also be of relevance to these organisations and processes. As with our ongoing PREDICTS project, we will seek endorsement for this project from GEO BON, making clear that we will pass all our data holdings to GEO BON at the end of the project. UNEP-WCMC will use our modelling framework for biodiversity projections in response to requests from decision-makers, including the international conventions, governments and businesses. Because we will be developing our framework in partnership with UNEP-WCMC and other project partners, it will translate directly into evaluations of policy options for land and biodiversity management.

2. UK and other national governments: Model outputs and projections at sub-global spatial resolution will be of interest to national governments for national-scale biodiversity assessments and conservation planning. UNEP-WCMC will make national summaries available via the 'conservation dashboard' on its home page. As well as influencing international policy processes, UNEP-WCMC also performs many projects for national governments and institutions (including the Department for Environment Food and Rural Affairs in the UK); as part of our collaboration with UNEP-WCMC, we will provide predictions to inform these projects, where relevant. Additionally, the UK government is a member of GEO, though Defra, so may benefit directly if this project fulfils part of their obligations.

3. Members of the public: The NHM has a proactive Press Office that is experienced in engaging with national and international media and in coordinating publicity between multiple institutional press offices. Press Office staff will draft and release press releases in conjunction with the PI and Researcher Co-I, to coincide with publication of significant research results, thereby disseminating the work as widely as possible. The NHM also runs informal learning activities on site in South Kensington, including popular public presentations on research results as part of the regular "Nature Live" series of talks. These daily talks, of 30 minutes' duration, focus on aspects of NHM science output in an informal setting and allow direct public access to scientists. Nature Live talks are attended by diverse audiences that represent all sociodemographic groups in the UK as well as international visitors.