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

Abstract

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Response to: Comment on “Peatland carbon stocks and burn history: Blanket bog peat core evidence highlights charcoal impacts on peat physical properties and long‐term carbon storage” by Evans et al. (Geo: Geography and Environment 2019; e00075)

“…While we appreciate that the comments made by Evans et al (2019) are well intended, we remain confident in the robustness of our data and below we defend the methods and main results. Importantly, they found that prescribed burning only caused significant reductions in peat and C accumulation rates within the most intensive 10-year burning treatment; however, carbon and peat were still accumulating at a considerable rate (Marrs et al, 2019). Evans et al stated that our findings "could be net beneficial for C sequestration" and that this is "contrary to most current understanding."…”

“…We would also like to clarify that our previous and additional criticism of Garnett et al (2000) is exclusively based on the data presented. Thirdly, "current understanding" may be incorrect because, in addition to our study, several new studies (as identified by the authors) have weakened the unsubstantiated claim that prescribed burning greatly reduces carbon accumulation, particularly if considering management and monitoring timescales (e.g., Clay et al, 2010;Marrs et al, 2019). While we appreciate that the comments made by Evans et al (2019) are well intended, we remain confident in the robustness of our data and below we defend the methods and main results.…”

“…Indeed, as the only major study on prescribed burning impacts on soil carbon stocks at that time (as highlighted by Evans et al, 2014), we feel that Garnett et al (2000) should be subject to detailed scrutiny in order to determine gaps in our understanding and inform future research. Notably, a recent study by Marrs et al (2019) used the same plots as Garnett et al (2000) but employed more detailed lead isotope peat depth dating. For this, we provide further clarification and justification of our methods, together with providing some additional references and graphical information to support the interpretation of our findings and our overall conclusions.…”

Comment on: “Peatland carbon stocks and burn history: Blanket bog peat core evidence highlights charcoal impacts on peat physical properties and long‐term carbon storage,” by A. Heinemeyer, Q. Asena, W. L. Burn and A. L. Jones (Geo: Geography and Environment 2018; e00063)

“…This is because Garnett et al used the (more reliable) 1950s SCP take-off date to date their cores, and did not therefore analyse SCPs up to the surface of all cores, where peat is less decomposed and reliable SCP measurement difficult (Swindles, 2010). Given that Moor House was part of the Appleby Castle shooting estate prior to becoming a National Nature Reserve, the occurrence of such pre-experimental fires is to be expected; indeed recent work by Marrs et al (2018) suggests that a site-wide fire occurred in around 1923. Another core analysed by Garnett and Stevenson (2004) revealed the presence of a deeper pre-1954 charcoal layer (presumably the one used by Heinemeyer et al to argue that the Garnett et al reconstruction was incorrect), which was clearly attributable to a previous fire.…”

“…Recent papers suggesting that fire is an essential tool for peatland management (Davies et al, 2016), that the carbon implication of current practices of peat burning may be "not as bad as previously thought" (Marrs et al, 2018), or that they may even deliver carbon benefits (Heinemeyer et al, 2018) thus have the potential to significantly influence policy. Activities that provide climate change mitigation benefits may be favoured by future public subsidy schemes (https://www.gov.uk/government/speeches/michael-gove-speech-on-uk-climate-change-projections; Committee on Climate Change, 2018), while those that generate emissions may be penalised.…”