The role of plant-soil interactions in peatland carbon cycling at a Scottish wind farm

GE Environmental Sciences;Q Science (General)

Richardson, Harriett Rose ; Natural Environment Research Council (NERC) ; Waldron, Susan

University:University of Glasgow

Department:School of Geographical and Earth Sciences

关键词: peatland, wind farm, carbon cycling, plant functional type, microclimate, greenhouse gas emissions;   

Others  :  http://theses.gla.ac.uk/5636/1/2014richardsonphd.pdf

来源: University of Glasgow

【 摘 要 】

Northern peatlands play an important role in the cycling of carbon (C) globally, and contain up to one third of the world’s soil C despite only covering a small percentage of its land surface (Gorham, 1991). Changes in climate and land use are increasing the vulnerability of these vast C stocks, by altering the conditions favourable for peat accumulation and therefore C sequestration. The establishment of wind farms on peatlands is increasing in the UK, as a result of the growing need for sustainable energy and the suitably high wind speeds that are typical to these upland ecosystems (Smith et al., 2014). There is limited understanding of the impacts of operational wind farms on their host ecosystems, but evidence to suggest that wind farms create microclimate conditions by altering ground-level temperature is increasing (Armstrong et al., 2014a; Baidya Roy and Traiteur, 2010; L. Zhou et al., 2012). The sensitivity of peatland C cycling processes to wind farm-induced microclimatic changes represents a considerable gap in knowledge. Further, the role that aboveground and belowground peatland communities have in mediating the effects of wind farm microclimates on C cycling processes remains unknown. By examining plant-soil interactions across a peatland at Black Law Wind Farm and under a range of microclimate conditions in the laboratory, this thesis aimed to investigate the influence of plant functional type (PFT) and microclimatic conditions on physical, chemical and biological peatland properties, greenhouse gas (GHG) emissions and litter decomposition. Results show that a PFT legacy in peat plays a mediatory role in the response of CO2 and CH4 emissions to microclimatic differences in temperature and water table. Mass loss of litter is primarily driven by PFT differences in litter quality, with interactions between litter types controlling decomposition of litter mixtures via non-additive effects, and interactions between litter types and PFT legacies in peat affecting the likelihood of home-field advantage and disadvantage (HFA and HFD) litter mass loss. This thesis demonstrates that the direct effects of microclimatic changes in temperature and water table are important drivers of peatland C cycling processes; however the indirect effects of microclimate change on plant community composition e.g. the relative proportion of PFTs could influence these processes to a greater extent. Examining the importance of PFTs in C cycling processes at wind farm peatlands is important in improving predictions of peatland C sequestration under future climate change scenarios, and in calculating the C savings achieved by land-based renewable technologies.