For centuries peat bogs have been viewed as wastelands on the neglected margins of the landscape. Burnt for fuel, dug up for horticulture and drained for agriculture, they have been extensively damaged and destroyed by human activity. Now peat bogs are facing an even bigger threat through climate change.
Peat bogs occur widely in northern regions which have experienced greatest climate change over the last hundred years, and are likely to experience the greatest change this century. Whilst peat only covers 2-3% of the global land surface, climate change impacts on peat bogs are disproportionately important. Whilst a typical bog may have peat 2-5m deep, this peat is roughly 50% carbon, meaning that the total quantity of carbon stored is vast.
Since the last ice age peat bogs have been gradually trapping carbon dioxide from the atmosphere, accumulating peat, and thereby cooling climate. However there is considerable uncertainty about whether this climate cooling will continue in a future where bogs are increasingly affected by climate change.
Surprisingly we do not currently know whether bogs will store more or less carbon in the future. Some experimental studies have suggested rapid carbon loss, which will accelerate climate change. However some palaeoecological studies have suggested precisely the opposite. One of the reasons for this uncertainty, is the simplistic design of many climate change experiments. In particular, no field experiments realistically simulate the seasonal reduction in water table expected under future climates.
To understand the impact of climate change on bogs and address some of the limitations of previous experiments, in 2010 we established an experiment on a bog in Wales. Cors Fochno is a beautiful bog on the estuary of the River Dovey on the west coast of Wales. The site is a nature reserve managed by Natural Resources Wales who have been extremely supportive of our research.
Our experiment consists of treatments which both warm and dry experimental plots. Some of the plots are passively warmed using open top chambers which look like mini-greenhouses, warming the peat surface. Others are dried using a network of pumps and pipes to remove groundwater and simulate a summer drought. The final group receives a combination of both treatments.
Initially we saw little change in vegetation, but now White Beak Sedge is encroaching at the expense of Sphagnum. This may be important because Sphagnum mosses are much better than vascular plants at forming peat and locking away carbon. These slowly-developing impacts stress the importance of the long-term research supported by the Ecological Continuity Trust.
Sadly the future of the experiment is now threatened by the absence of long-term funding. While ECT grants have been extremely helpful to bridge the gaps between longer-term grants the continuing need to update and replace infrastructure means that more substantial funding will be required to continue the experiment in the long-term.
It is an unfortunate truth that many ecological experiments have to be terminated at the point where they are just becoming really interesting. We hope that this will not be the fate of the Cors Fochno Experiment.
Author: Dr Richard Payne, University of York