Abstract
The aims of PEATBOG are to understand how the biodiversity and ecosystem functions of peatlands across Europe are impacted by nitrogen pollution and climate change, and 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 the impact of these stresses, and whether they will act independently or synergistically. We hypothesize that above critical thresholds of nitrogen deposition there will be reductions in the diversity of all species, with bryophytes being particularly sensitive. Sensitive vegetation will be replaced by more nitrophilic species, and these changes, together with enhanced microbial decomposition, 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 soil solution and rising concentrations of greenhouse gases (N2O, CO2, CH4) released to the atmosphere. We anticipate that these responses to nitrogen pollution will become exacerbated under climate change, and under extreme conditions may lead to a breakdown in the ecosystem and mass carbon and nitrogen loss. To address these concerns, we will determine the relationships between peatland above- and below-ground species richness and nitrogen deposition across northern Europe. Using field manipulations to alter water table and temperature, we will measure the nature of the interactions 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 to develop bio-indicators of risk to peatland ecology and functional integrity caused by elevated nitrogen deposition and climate change. On a national and European scale, this will allow us to identify the most vulnerable peatlands and to evaluate current policy such as critical loads thresholds. This is the first study investigating the interactive effects of N deposition and climate on both vegetation and microbial biodiversity in peatlands. 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.
Sweden