Interactions between nitrogen deposition, biodiversity and and the biogeochemical cycling of nitrogen and carbon in European peatlands
From 05/2009 to 04/2012Principal Investigator
: Christian Blodau
: Yuanqiao Wu
, Kasia Zajac
Peatlands are found throughout Europe where a suitable cool, moist climate exists; they are particularly widespread in Russia, the Scandinavian countries, the British Isles, and north-eastern Europe. Partially decomposed organic material accumulates as peat due to an imbalance between the rates of primary production and decomposition, usually because of restrictions on soil oxygen availability, temperature and nutrients. Peatlands are the world’s largest soil carbon pool, support a unique biological community, and have a high capacity to filter pollutants. Maintaining these critical functions of peatlands depends upon protecting the biological and structural integrity of the whole ecosystem, both above- and below-ground. However, because they are more directly influenced by precipitation, temperature, and nutrient inputs than most terrestrial ecosystems, peatlands are highly vulnerable to changes in these drivers.
There is evidence that peatlands are impacted by N pollution, via Sphagnum loss, species composition shifts and elevated C and N cycling, at levels as low as 5 kg N ha-1y-1 , within the range received by most peatlands in Europe. There is also evidence that climate change will exacerbate that stress. The combination of continued N pollution, increasing temperature, and declining summer precipitation may shift vulnerable European peatlands toward local species extinction, biogeochemical cycle disruption, uncoupling between vegetation and microbial diversity and, in some cases, substantial carbon loss and ecosystem change.
The aims of PEATBOG are to (1) understand how the biodiversity and ecosystem functioning of peatlands across Europe are impacted by nitrogen pollution and climate change, and (2) develop meaningful indicators of risk to these impacts.
Witin PEATBOG, the sub project 3 aims at understanding the mechanisms of pollutant impacts on biogeochemistry and feedbacks to the C and N cycles. It focuses on detailed investigations of processes, in particular using isotopic tracers, and will also synthesise the results of the PEATBOG experiments into a biogeochemical model. Major processes include 15N translocation experiments in both laboratory mesocosms and field manipulation sites, and calculation of carbon accumulation rates in N deposition transects using 210Pb. Changes in C and N allocation patterns and N dynamics are analysed in relation to climate and nitrogen deposition, as well as feedbacks between these processes and biodiversity.
Co-operators: Nancy Dise and Simon Caporn, Manchester Metropolitan University; Bo Svensson and Per-Eric Lindgren, Linköping University; Jos Verhoeven, Utrecht University; Lucca Bragazza, University of Ferrara