Experimental evidence for sustained carbon sequestration in fire-managed, peat moorlands

Peat moorlands are important habitats in the boreal region, where they store approximately 30% of the global soil carbon (C). Prescribed burning on peat is a very contentious management strategy, widely linked with loss of carbon. Here, we quantify the effects of prescribed burning for lightly managed boreal moorlands and show that the impacts on peat and C accumulation rates are not as bad as is widely thought. We used stratigraphical techniques within a unique replicated ecological experiment with known burn frequencies to quantify peat and C accumulation rates (0, 1, 3 and 6 managed burns since around 1923). Accumulation rates were typical of moorlands elsewhere, and were reduced significantly only in the 6-burn treatment. However, impacts intensified gradually with burn frequency; each additional burn reduced the accumulation rates by 4.9 g m−2 yr−1 (peat) and 1.9 g C cm−2 yr−1, but did not prevent accumulation. Species diversity and the abundance of peat-forming species also increased with burn frequency. Our data challenge widely held perceptions that a move to 0 burning is essential for peat growth, and show that appropriate prescribed burning can both mitigate wildfire risk in a warmer world and produce relatively fast peat growth and sustained C sequestration.