Changes in plant functional diversity matters for peatland carbon cycling

Summary The issue of carbon (C) cycling is high on the scientific and political agenda, largely because of concerns over the ability of ecosystems to store C in the face of global change. Much of the research in this area is focussed on moorlands, or peatlands, because they act as vast stores of terrestrial C, currently estimated to be one-third of the global C stock. The main worry here is that changes in climate and land use will destabilise these stores, releasing C back into the atmopshere as carbon dioxide, thereby boosting global warming. To date, most research in this area has looked at how changes in weather, such as climate warming and drought, might affect these important C stores in peat. Very little, however, is known about how land use, and changes in vegetation that result from management, influence these C stores. Land use, for the production of goods and services, is one of the most substantial human influences on Earth, affecting one third to one half of the land surface. While peatlands are thought to be of limited value for farming, they are subject to much land use activity from forestry, peat extraction for fuel and horticulture, rough grazing and game management. All these activities strongly affect the make-up of the vegetation, often increasing the growth of fast growing plants, such as grasses, at the expense of heather, the plant most commonly associated with moorland. In the long-term, this could influence ecosystem C storage by changing the balance between C input to soil, from plant litter and root material, and its loss by decomposition and respiration. In this proposal, we tackle this issue by testing how changes in vegetation resulting from long-term management, namely buring and grazing, influence the cycling of C in peatland ecosystems. To do this, we will use a long-term (50 year) field experiment at the Moor House National Nature Reserve, northern England, with various grazing and burning treatments. We will manipulate vegetation of different management systems to test how this affects C cycling in peatland. To do this, we will use novel pulse labelling approaches which allow us to trace the uptake of C by plants and its transfer to soil, and then back to the atmopshere.