Dr Isabelle Durance
My current research focuses on:
The role of biodiversity is sustaining key ecosystem services
The application of landscape ecology to biodiversity conservation
The detection and modelling of climate change impact on river ecosystems.
Investigating thresholds and resilience in the functioning of coupled ecological and social systems
Keywords: biodiversity, conservation, climate change, ecosystem function, ecosystem services, landscape ecology, pattern analysis, sustainability, freshwater ecosystems .
Landscape near Odessa (Ukraine)
Initially trained in Montpellier in agronomic engineering, I began my career investigating the dynamics and landscape ecology of agriculture in rural areas, in particular the processes affecting biodiversity. In addition to understanding how agriculture transformed landscape condition, I examined how agriculture affected the flux of matter and energy at the landscape scale, and assessed the consequences for priority habitats and organisms. Using systems-based approaches, I also investigated water and soil pollution, in particular with respect to agricultural runoff and catchment-scale influences on turbidity, nitrates and drinking-water quality. Ensuring sustainable resource-use is one of the main applications of landscape ecology, and these projects were among the initial applications of tools such as Geographical Information Systems (GIS) and remote sensing to understanding larger-scaled processes linking human resource use and biodiversity conservation.
My current research focuses on four key areas: the role of biodiversity in sustaining ecosystem services, applied landscape ecological perspectives to biodiversity conservation, assessment and modelling of the impact of climate change on upland and lowland stream ecosystems, and identifying thresholds and factors of resilience in coupled ecological and social systems. Much of my approach relies on the analysis of either large scale patterns or long term patterns in species distribution and environmental characteristics (including climate) to provide testable hypotheses on how ecosystems function. These are in turn tested in the field, most often using upland stream ecosystems as models.
1. The role of biodiversity in sustaining ecosystem services
Since June 2012, I have been leading DURESS – Diversity of Upland Rivers for Ecosystem Service Sustainability. The project is part of a major Research Council initiative called BESS - Biodiversity and Ecosystem Service Sustainability - to assess the role of biodiversity in delivering the key ecosystem services on which we rely. This £3 million project brings together a consortium of 28 researchers from a range of disciplines and institutions, and is actively supported by seven key stakeholders who represent the water industry, the leisure industry, policy makers, land owners and land managers.
DURESS will investigate how organisms and ecosystem functions maintain river ecosystem services. This is crucial knowledge because they are affected by pollution, catchment land use and climate change. The cost implications of these effects are large, for example for recreational fisheries, water treatment and high-value river biodiversity. By contrast, there is large potential to manage rivers and their catchments positively to increase the ecosystem service value of rivers by enhancing beneficial in-river organisms.
DURESS focuses on four river ecosystem services that are biodiversity-mediated: the regulation of water quality; the regulation of decomposition; fisheries and recreational fishing; and river birds as culturally valued biodiversity. Each is at risk from climate and land-use change, and potentially sensitive to disturbance at different thresholds and at different time-scales.
The four services chosen for investigation vary in attributable market values, and to understand them requires integration from the physical, biogeochemical, ecological and socio-economic sciences that the project partnership provides. Using river microbes, invertebrates, fish and river birds at levels of organisation from genes to food webs, DURESS will test the overarching hypothesis that: Biodiversity is central to the sustainable delivery of upland river ecosystem services under changing land-use and climate.
DURESS ranges from small experimental catchments to the whole uplands of Wales, and at time steps from weeks to decades. We chose upland Wales specifically as a well-defined geographical area of the UK that is particularly rich in the spatially extensive and long-term data required for the project, and where rivers are major landscape features.
2. Landscape processes and biodiversity conservation
Segmentina nitida Copyright @ Natural England
The spatial distribution and persistence of patches of different habitat quality can determine population viability and species composition within ecosystems. This perspective from landscape ecology is increasingly valued in the conservation or restoration of threatened organisms, particularly where the underlying ecological processes can be identified. Links between landscape pattern, process and biodiversity formed much of my work prior to joining Cardiff University (Poudevigne & Baudry, Eds. 2003), and this theme continues. Typical approaches combine ordination, linear models and variance analysis with geo-statistics, GIS and remotely sensed data, and these are active areas of both my research and teaching (Leuven, Poudevigne and Teuuw, Eds. 2002).
By comparison with terrestrial ecosystems, landscape ecological applications to freshwaters have been few. Previous collaborative work with the Universities of Nijmegen (NL) and Rouen (F) brought landscape and system perspectives to river restoration and ecological risk assessment in the Seine and Rhine (Poudevigne et al 2002; Leuven & Poudevigne 2002). Work with the CEMAGREF (France) on the upper Seine illustrated how reproductive success in northern pike Esox lucius is explained by the spatially explicit arrangement of habitat quantity, and accessibility to spawning patches during flooding. These principles have been extended in a general review of the importance of scale and spatial pattern in fisheries management (Durance et al. 2006).
Augmenting previous work on angiosperms, insects, amphibians, fishes and birds in the Seine valley (Ernoult et al. 2003; Poudevigne & Baudry 2003, De Nooij et al. 2004), recent projects include EA/NERC sponsored research into the ecology of three Red-listed snails on English grazing marshes showing how connectivity between suitable ditches has a major influence on distribution (Durance et al. 2006; Niggebrugge et al. 2007). Further modelling analysis concluded that in general, conserving priority species could extend the array of distinct environments that are protected for their specialized biodiversity and environmental quality (Ormerod, Durance et al. 2010).
3. Climatic effects on river function
View of Llyn Brianne catchments
By directly affecting temperature and hydrology, climate affects a range of major processes in river systems. As a result, organisms here may be among the most sensitive of all to climate forcing. Long-term data from the Llyn Brianne experimental catchments (1981-2005) have revealed clear climatic effects on invertebrate assemblages in headstreams (Durance & Ormerod 2007). Funded by the Environment Agency, CCW and Natural England, we developed models to link invertebrate response to climatic drivers. Named CLIO (CLimate-Invertebrate Optima), these models have since been used in conjunction with Hadley Centre forecasts for Wales to project future climatic effects on composition and abundance. Results highlighted in the journal Nature suggested that in the most species-rich streams, the abundance of invertebrates in the spring-time could decline by one-fifth for every degree of temperature gain, with major consequences on energy flows.
Cooler-water species are most at risk. In the Llyn Brianne catchments, we found evidence for the role of climate in the local extinction of a cool-water triclad Crenobia alpina (Durance & Ormerod in press). Others species are also at risk. In the adjacent Wye, our research using Environment Agency data showed that populations of Atlantic salmon and brown trout fell respectively, by 50% and 67% between 1985 and 2004, a decrease correlated with mixed models representing a trend towards hotter, drier summers (Clews, Durance et al in press).
Upland stream in deciduous forest © I.Durance
Climate change will also interact with other large-scale processes in upland catchments such as recovery from acidification and catchment land use. Research to assess these interactions over long timescales is continuing on the Llyn Brianne experimental catchments. We have recently shown (Ormerod & Durance 2009) that climate affected the recovery pattern of streams affected by acid deposition. Our results reveal that wet winters increased acidity in moorland and forest streams sufficiently to offset 21-21% of the total 25 year decrease in H+ concentration in these streams. Following on these results, we are investigating the functional structure of upland stream invertebrates, and our data show that there was a long-term persistence in stream function in Llyn Brianne despite inter-annual variation in steam temperature (>3ºC) and pH (variations>1.5 units between years). In contrast, we found that varying riparian land use offers an option to promote resilience in functional guild composition.
In river ecosystems, climate change interacts with other large-scale processes such as recovery from pollution and catchment land use. Our work shows that adaptation management could minimize some climate change impacts on stream ecosystems. For example, application of the CLIO models on lowland rivers in southern England showed that recent winter-biased warming in the chalk-streams had been insufficient to affect invertebrates negatively over a period of improving water quality (Durance & Ormerod 2009). Concomitantly, we have recently shown (Ormerod & Durance 2009) that climate influenced the recovery pattern of upland streams affected by acid deposition. Our results reveal that wet winters increased acidity in moorland and forest streams sufficiently to offset 21-21% of the total 25 year decrease in H+ concentration in these streams.
4. Resilience in coupled ecological and social systems
Spatially explicit models relating ecosystem services, land use and climate are key tools to build adaptation strategies that promote sustainable provisioning of ecosystem services. Our specific research interests lie in building a model of the ecosystem service- land use -climate relationships, using Wales as a case study.
Kriging interpolation of chemical river quality using Environment Agency data for the NEA
Since January 2012, I lead the Resilience in natural-social systems theme of the Sustainable Places Research Institute, in collaboration with Prof Susan Baker, Prof Mike Bruford, and Prof Ian Hall. Place-based, this theme investigates the sustainable management of natural landscapes such that they may continue to deliver the services human wellbeing depends on, while also maintaining biodiverse and functional ecosystems.
Ensuring sustainable environments, in a world where the climate and other conditions are changing, requires a new understanding of how physical, ecological and social processes are inter-related.
Interactions between these processes across different scales both determine quality of life and how natural systems can function. Understanding their coupled relationship is vital for adaptive systems of management and governance that can ensure sustainability despite increased pressure stemming from climate change, food security, water scarcity…
By aiming to understand these interactions, the programme will to address the apparent ‘misfit’ between physical environments, eco-systems and social institutions. Working at the interface between ecology, earth sciences and social sciences, our team aims to develop new concepts and tools to answer such questions as:
- what combinations of ecosystems and social systems are sustainable? How can these relationships be strengthened to foster higher resilience?
- how can non-sustainable trajectories be recast?
- what scales are relevant to the sustainable management of natural resources and ecosystem functions, and how can findings be translated from one scale to another?
- what tools and measures best assess current interactions between societies and their natural environments, and can also be used for predictive purposes?