Recent Environmental Change and Biodiversity
The aims of this theme are (i) to use long-term chemical and biological measurements and lake sediment records to reconstruct past freshwater environments and hence assess environmental change over decadal to centennial timescales and (ii) to assess threats to biodiversity in both terrestrial and aquatic systems and to understand the role of biodiversity in ecosystem functioning, its importance in providing resilience to external stressors, including species invasions, and its role in moderating biogeochemical cycles, especially carbon. The emphasis is on understanding the impact of human activity over the last two centuries (“the Anthropocene”). The central challenge is to develop methods of disentangling the respective influences of the different stressors that operate singly and together in driving environmental change and, increasingly, to identify the role of climate change in modifying ecosystem behaviour.
- Recovery of surface waters from acidification (Battarbee, Flower). This work has assessed the impact of reductions in acid deposition on the recovery of acidified lakes and streams in the UK uplands, based on a major Defra-funded monitoring network that began in 1988. The work has shown: (i) that there have been significant improvements in water chemistry over the last 20 years; (ii) that only limited biological recovery has so far taken place; (iii) that nitrate has replaced sulphate as the dominant acid anion in some upland waters, posing both an acidification and eutrophication threat to the continued recovery. This work has demonstrated the power of long-term observations in identifying ecological trends and the value of combining ecological and palaeoecological data in defining the status of freshwater ecosystems. Through chemical modelling of critical loads exceedance across the UK it has provided the evidence base for Defra's policies on long-range transported air pollutants under various EU and UNECE directives and protocols.
- Contamination of environments by toxic substances (Rose, Yang, Sayer) This work aims to enhance our understanding of the spatial and temporal distributions of toxic pollutants, including metals such as lead, cadmium and mercury and persistent organic pollutants (POPs) on a national and international scale, their impact on aquatic biota and human health. This work has: (i) provided the first historical sediment records for various metals (especially Hg) and POPs in mountain lakes of Tibet, East Africa, upland Europe and polar regions (ii) assessed the biological impact of organometallic pollutants in lowland lakes; (iii) determined the role of climate change on the remobilisation of trace metals deposited over the industrial period through soil erosion in the uplands; (iv) used detailed temporal and spatial distributions of industrially derived fly-ash to provide the first empirical assessment of black carbon deposition over the industrial period.
- Impact of climate change on freshwater ecosystems (Battarbee, Bennion, Rose, Yang) This work (primarily through the coordination of two large EU projects – Euro-limpacs and REFRESH) has investigated the impact of projected climate change on the ecology of lakes, streams and wetlands, and how future impacts of climate change on freshwater ecosystems might be mitigated. This research has also demonstrated the importance of understanding the indirect effects of climate change such as the impact on pollution behaviour and catchment biogeochemistry. More specifically, it has shown: (i) the importance of understanding natural variability in aquatic ecosystems; (ii) how climate change might confound the recovery of acidified upland waters in the UK and (iii) that for lowland lakes eutrophication continues to mask the influence of climate change on ecosystem status.
- Freshwater biodiversity (Sayer, Bennion, Flower, Mackay, Jones, Battarbee) This work demonstrates: (i) the power of macrofossils in shallow lake sediments to record regime shifts from clear to turbid water conditions; (ii) how differences in the biodiversity of lake districts can be related to the connectivity between habitats; (iii) how changes in diatom assemblages in the sediments of acidified lakes can be used to indicate the creation of novel ecosystems; (iv) how hydrology and hydro-period controls aquatic diversity in the Okavango Delta, Botswana, a major, tropical wetland (v) how human activity has degraded the biodiversity of North African wetlands.
- Changing Ecology of Tropical Forests (S. Lewis). This work tests the hypothesis that remote contemporary tropical forests are being altered by global environmental changes including (i) the first comprehensive investigation into changes in forest composition and function across the tropics, using long-term phytodemographic inventory plots, overturning the dynamic equilibrium hypothesis and providing key insights into recent, current, and likely future functional trajectory of the tropical forest biome; (ii) demonstrating that remaining tropical forests are increasing in mass and absorbing carbon dioxide from the atmosphere, substantially buffering the rate of increase in atmospheric carbon dioxide concentrations and (iii) that this increase is vulnerable to a changing environment, particularly if climatic trends towards more seasonal climates occur.
- Biodiversity conservation in relation to changing land-use pattern, climate change and invasive species (Axmacher) Current research on invertebrates in Northern China and the UK has revealed (i) biodiversity patterns in space and time as well as global change effects; (ii) the influence of management strategies for biodiversity conservation and (iii) the effects of invasive species on different communities.
The research of this cluster is largely undertaken by the Environmental Change Research Centre.
Click here for a list of some of our recent research grants.
- Prof Tim Atkinson
- Dr Jan Axmacher
- Dr Helen Bennion
- Dr Roger Flower
- Prof Jonathan Holmes
- Dr Viv Jones
- Dr Simon Lewis
- Dr Anson Mackay
- Prof Neil Rose
- Dr Carl Sayer