Carbon storage in Pennine moorland and response to change

Abstract

The climate of the Earth is expected to warm due to increasing atmospheric concentrations of greenhouse gases, particularly carbon dioxide (CO 2). The impact of this change on terrestrial ecosystems is uncertain, yet these ecosystems contain three times more carbon (C) than the atmosphere and could considerably augment anthropogenic CO2 emissions. This thesis aimed to quantify the terrestrial C stored in an area of Pennine moorland and predict its response to changes in climate and management. The area of soil and vegetation types was determined using existing maps of the study site and a geographical information system. Vegetation C was assessed using results from published productivity studies, and soil C was evaluated from a programme of field sampling. Most C was contained in peat soils and comparison of the results with the UK's national C inventory identified inaccuracies in the national values. The impact of sheep grazing and moorland burning on C storage was investigated by utilising long-term experiments at the site. Areas where sheep had been excluded for forty years were compared to grazed areas and burning was investigated using a randomised block experiment. Grazing had little impact on terrestrial C storage, but regular burning significantly reduced C sequestration in peats. The response of the C store to climate change was investigated by i) determining the impact of past climate on C storage and ii) developing a predictive model by measuring the underlying processes of C input and output in the ecosystem. Both approaches illustrated the sensitivity of the ecosystems C balance to climate, suggesting that global warming will reduce C accumulation at the site and, therefore, augment atmospheric CO 2 concentrations. The novel use of near infrared reflectance spectroscopy to characterise peat samples was also demonstrated, indicating opportunities for application of this technique in palaeoecological studies of peats.