The coherence of ecological stability among ecosystems and across ecological scales

Lead Research Organisation: University of Sheffield
Department Name: Animal and Plant Sciences

Abstract

Climate and environmental change is impacting on all ecosystems - marine, freshwater and terrestrial - in the world. The changes are associated with a wide range of 'stress' like rising temperature, drought, nutrient run-off, pesticides, over-harvesting and habitat loss. For example, more than 50% of freshwater aquatic communities that provide drinking water, recreation and food are threatened by detrimental anthropogenic stress in the last century, including rising temperature, pollution and N/P run-off. In marine communities, climate change, acidification, overfishing and pollution threaten food resources, coastal communities and carbon storage capacity. In terrestrial communities, rising temperatures, agricultural run-off, habitat fragmentation, pollution and more frequent extreme events threaten to forest, grassland and agricultural communities and the services they provide.

This detail suggests that the stability of populations, communities and ecosystem function is threatened by multiple, simultaneous stressors. Making predictions about these effects is hard. We highlight three substantial challenges to advancing the understanding of stability within and among ecosystems.

First, there are lots of ways to measure stability and dynamics and they work at different ecological scales - some are about individual species and others are about diversity of many species.. We must demonstrate the value of using simultaneously multiple measures and the appropriateness of them at different ecological scales.

Second, the kind of data we use to assess the stability and dynamics of organisms - numbers in time and space and among species - have properties that must be accounted for, but rarely are. We know that the numbers of a species today and yesterday are more related than numbers today and 5 years ago. This is temporal correlation. We know that populations that live close to each other will be more alike than those far apart. This is spatial correlation. And we know that species that are closely related will be more similar than distantly related ones. This is evolutionary correlation. The majority of stability indicators have failed to accommodate these disruptive and well know features of real data.

Third, there might be interactions among stressors. This means that the effect of one stressor depends on what the presence, absence or magnitude of another. This make prediction challenging, especially if we don't know about the dependencies. We need theory and data to understand how, and at what scales, multiple stressors impact stability.

Our project aims to deal with all of these using three research objectives.

1. Develop improved indicators of stability, at multiple ecological scales (e.g. biomass/abundance, community structure/diversity, function), that formally rectify long recognised but rarely addressed issues arising from spatial, temporal and phylogenetic covariation;
2. Make predictions about stability among ecosystems (coherence) facing multiple, simultaneous stressors produced by advanced simulation models that allow insight into the intrinsic processes and feedback mechanisms driving stability; and
3. Test model predictions and the efficacy of improved indicators of stability using experimental and field collected data from terrestrial, marine and freshwater ecosystems.

Planned Impact

The research proposed here is fundamental. It does however involve the analysis of large scale datasets linked to NERC/Defra research programmes on marine fisheries, CEH/UK Government data on freshwater and pan-european avian datasets overseen by the RSPB. Our work will establish a platform that informs on the common and distinct features of communities and drivers of environmental change that impact on the stability of ecological communities. Our set of tools and the cross-system analysis of stability will ultimately help scientists and natural resource managers understand if, how and when we can generalise about stability. In this context, we see three major groups of beneficiaries:

1. Policymakers and managers concerned with the conservation of biological diversity (marine, freshwater and terrestrial) in the face of environmental change. Our research will provide an understanding of the mechanisms that mediate response to environmental change, and how they facilitate stability at multiple scales.
2. The public, for whom food web networks provide an accessible route to understanding of complex ecological principles like stability and ecosystem function. Our focus on models and data that can be defined by networks lends itself to illustrating how well-known forms of environmental change can interact with biodiversity and ecosystem function and services. Our project provides an important opportunity for education and outreach, increasing public understanding of these key ecological principles.
3. 1st Year Minority/Women Students. In the past few years, there has been a decrease in the number of summer research bursaries available to young people interested in learning about science. Furthermore, the issues of supporting women and minorities in science (STEM) and computer programming has increased. Our research focused on STEM topics and computer modelling provides an ideal opportunity to experience a combination of ecology and conservation via computer based activities, to learn first -hand how research works and whether a career in research may be of interest.

Publications

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