URGENCY application to investigate the effects of severe summer fire on below-ground heathland processes

Climate change is predicted to result in warmer, drier summers in the UK as we move through the current century. The associated increase in both the frequency and severity of summer fires is likely to result in major changes in the structure and function of terrestrial ecosystems. Human activities are also responsible for disturbing the global nitrogen cycle; this has resulted in a diverse range of effects, from altered rates of nutrient cycling and carbon storage to changes in plant community composition. Fire and nitrogen deposition are major drivers of ecosystem change and may result in the loss of biodiversity and compromise the provision of essential ecosystem services. A recent, severe heathland fire at our long term nitrogen manipulation study site presents a unique opportunity to quantify interactions between these two important global change phenomena. Nitrogen additions over the past 7 years have resulted in changes in the activity and composition of the soil microbial community, and storage of additional nutrients both above- and below-ground. These pre-existing differences in microbiology and nutrient availability can be expected to influence the response of the microbial community to a major fire, with knock on effects on nutrient cycling and nutrient economy. Results will provide important insight into post-fire microbial community dynamics in soils of contrasting composition, and its link with soil nutrients. In addition, we will obtain extremely valuable information on the potential for periodic, high impact perturbations to mitigate observed changes in belowground diversity and ecosystem function associated with elevated nitrogen deposition.