PEATBOG: Pollution, Precipitation and Temperature Impacts on Peatland Biodiversity and Biogeochemistry (Biodiversa Programme)

The aims of PEATBOG are, firstly, to understand how the biodiversity and ecosystem functions of peatlands across Europe are impacted by nitrogen pollution and climate change, and secondly, to develop meaningful indicators of risk to these impacts. The peatlands of northern Europe are major global sinks for carbon and support a unique biological community. Climate change and air pollution, however, threaten the structure and function of these ecosystems. Aerial deposition of reactive nitrogen and other pollutants has already caused a significant drop in diversity and functioning of peatlands in parts of Europe. There is also evidence that climate change will disturb peatland hydrology, through widespread summer drying, thus reducing net carbon sequestration. This project aims to understand how the combined stresses of nitrogen pollution and changing climate will affect biodiversity and ecosystem properties of peatlands. We hypothesize that above critical thresholds of nitrogen deposition, there will be reductions in the diversity of all species, with bryophytes being particularly sensitive. Accompanying a loss of sensitive types, there will be replacement by more nitrogen-loving species and both these changes will contribute to accelerated rates of nitrogen and carbon cycling. This will result in increased losses of nitrogen and carbon to the environment, seen principally as elevated levels of nitrogen in stream-water and rising concentrations of greenhouse gases (N2O, CO2, CH4) released to the atmosphere. We anticipate that these negative responses to nitrogen pollution will worsen under climate change due to increased microbial activity seen particularly in warm summer conditions as peatland water tables fall. To address these concerns, we will determine the relationship between peatland species richness and nitrogen deposition across northern Europe. Using field manipulations to alter water table and temperature, we will measure the nature of the interaction between nitrogen pollution and climate on peatland biodiversity and biogeochemistry. The importance of species diversity for ecosystem elemental cycles will be assessed within controlled experiments and across survey sites. We will also identify the associations between vegetation richness and soil microbial diversity, and how these are affected by nitrogen pollution and climate change. Increased understanding will help us develop bio-indicators of risk to peatland ecology and functional integrity caused by elevated nitrogen deposition and climate change. For example, we will be able to better account for climate change in the setting of nitrogen critical loads thresholds, and conversely, assess more accurately how nitrogen pollution affects the vulnerability of peatlands to specific degrees of warming and summer drought. This is the first study investigating the interactive effects of N deposition and climate on bog biodiversity, linking plant diversity with microbial diversity. Further novel aspects are the biogeochemical studies carried out at different scales in a well-coordinated combination of field surveys and associated nutrient assays, field manipulation studies and laboratory experiments involving stable isotope technology and molecular techniques. The study will adopt an innovative approach in using relational databases and GIS to strengthen data analysis and facilitate communication of the results with the stakeholder and end-user community.