Mechanisms and prediction of large-scale ecological responses to environmental change

Each natural ecosystem and each landscape on earth is unique. Yet, a range of generic biodiversity patterns is consistently observed: regularities in the numbers of co-existing species, their abundances, and their spatial distributions. How do ecosystems respond to wide-ranging stressors such as climate warming, habitat degradation and fragmentation, harvesting of biomass, and the accumulation of environmental pollutants? What do we mean by stability in an ecological context and how does it interact with these stressors? In order to address these pressing questions and be able to predict the responses of biodiversity to climate change and other stressors, it is essential to understand the fundamental processes that structure ecological systems over large spatial scales.

Recent breakthroughs in our understanding of spatial biodiversity patterns have been made possible by the development of models that reproduce large-scale ecological phenomena. The major known natural biodiversity patterns consistently observed in real ecological systems have recently been shown to emerge naturally in one such spatial model, the Lotka Volterra Metacommunity Model (LVMCM), which unifies the species-sorting, mass-effect, and patch-dynamics paradigms of metacommunity theory. In this project we build upon this prototype and use it to explore key fundamental and applied questions in macrecology.

The LVMCM represents reality at the level of abstraction at which policy formulates environmental targets, decision makers think about environmental impacts, and ecologists ask fundamental questions. By further exploring this modelling approach, we will address all five grand questions raised by NERC in the call text for this grant, which ask how, why and where ecosystems respond to large-scale stressors, and what role ecological (in)stability plays for these responses.

The model's simplicity will permit us to develop novel analytic theory for the processes controlling spatial biodiversity patterns and ecosystem responses to stressors on large scales, thus exposing principles that can inform an intuitive understanding of the mechanisms at work and--importantly--the conditions on which these mechanisms depend. Comparing field data with outputs from a process-based model like the LVMCM we will also develop novel ecological indicators and protocols for their computation from empirical datasets, together with guidelines on data requirements and reproducibility, for use by conservation ecologists and policy makers.

* Who could potentially benefit from the proposed research over different timescales?

It is by now widely accepted that global biodiversity is in the midst of a crisis. The main drivers of this crisis, land-use change, climate warming, pollution and overexploitation, have been identified. Less well understood are the relations between these drivers, biodiversity change, and the implications of such change for the health of ecosystems. As a result, conservation policies and measures might not always be as effective as they could be.

We expect the outcomes of this project to be directly relevant in the contexts of environmental policy and conservation biology. This project aims to influence decision makers (in both government and NGOs) and reaches out to both the experts advising them and to the general public. We will use a three-tiered communication strategy ranging from broad and simple to targeted and detailed communication. At the highest tier will be the communication of general insights to the public through scientific journalism. We will focus on publications in The Conversation, a popular science outlet that permits other news media to re-publish their content. At the middle tier, we will communicate some more technical results in short blog posts in dedicated web pages, or as guest contributions to established blogs. At the deepest tier, we will contact representatives of governmental agencies and NGOs, inform them of our wider-reaching publications (upper two tiers), and offer to visit these organisations to present, and discuss what our new results mean for the organisation's activities and approaches. This three-tiered approach means that the dissemination and use of this research will occur over the different timescales typical of self-published online content, popular science journals, and interactions with large organizations.

* How might beneficiaries benefit?

A simple example illustrates how management decision crucially depend on how fundamental ecological processes are understood. In a decision interpreting the Marine Strategy Framework Directive, the European Commission stipulated as an assessment criterion for good status of marine biodiversity that, for each of a comprehensive list of representative species, "The population abundance of the species is not adversely affected due to anthropogenic pressures, such that its long-term viability is ensured." This criterion fails to appreciate that:

1. The ecological communities in the assessed regions might slowly turn over in their species composition, either naturally or in response to anthropogenic pressures and
2. An important reason why we value biodiversity is that it permits ecological communities to adapt their composition to changing environmental conditions and pressures.

Conservation biologists advising governments and NGOs on conservation measures face similar dilemmas. Site selection for nature reserves faces the difficult question to what extent selected sites can sustain the biodiversity they currently harbour on their own. Population viability analyses depend on the question to what extent species can be assessed in isolation or need to be considered in the context of a complex networks of ecological interactions. In each case improvements in understanding of processes are likely to enable improvements in the efficiency of conservation measures. We expect our project to generate simple, intuitive explanations of the processes acting on large spatial scales and simple approximate formulae that quantitatively relate magnitudes and rates of ecosystem responses to the intensity and nature of stressors or conservation measures.