Accepted Article
Received Date : 05-Dec-2014 Accepted Date : 08-Dec-2014 Article type
: Letters to Editor
Corresponding author email id : [email protected]
Letter to the Editor on “Pyrogenic organic matter production from wildfires: a missing sink in the global carbon cycle”
Sharon A. Billings1, William H. Schlesinger2
1
Department of Ecology and Evolutionary Biology and Kansas Biological Survey, University of Kansas,
Lawrence, KS, USA 2
Cary Institute of Ecosystem Studies, Millbrook, NY 12545
Santín et al. (2014) report the conversion of different boreal forest biomass pools to pyrogenic organic matter (PyOM) during a forest fire, and suggest that ~100 Tg C y-1 may be converted to PyOM in boreal forests globally. They further suggest that PyOM formation represents a missing C sink. The phrase ‘missing C sink’ derives from a lack of closure in the atmospheric C budget. Approximately ⅓ of the CO2 emitted to the atmosphere via burning of fossil fuels and land use change cannot be accounted for after oceanic uptake and atmospheric accumulations are tallied (Schlesinger and Bernhardt 2013). To resolve the C budget, we must identify processes that 1) draw a meaningful quantity of CO2 out of the atmosphere, and 2) have increased their rate of CO2 capture since CO2 emissions from fossil fuels and land use change became important features of Earth’s C
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/gcb.12836 This article is protected by copyright. All rights reserved.
Accepted Article
cycle. The second criterion, perhaps less intuitive than the first, is critical: because atmospheric [CO2] was relatively constant for over 10,000 years of the Holocene, identifying a modern C sink does nothing to resolve Earth’s C budget if we cannot also demonstrate that the sink did not exist, or functioned at a reduced rate, prior to the Industrial Revolution. The formation of PyOM does not meet either criterion.
First, the formation of PyOM, regardless of the rate, does not remove CO2 from the atmosphere. When fire generates PyOM, regardless of the persistence of the resulting material, the process represents a transformation of one type of fixed C (biomass) into another (PyOM). As such, there is no direct effect of PyOM generation on atmospheric CO2. Second, PyOM has been forming in boreal forest soils for 1000s of years during which atmospheric CO2 was stable. Though the area of boreal forest subjected to burning apparently has increased in recent decades (Kasischke et al. 2010), there is no evidence that the increased burned area translates to enhanced rates of CO2 capture from the atmosphere via forest productivity. Some studies suggest that PyOM may promote short-term decay of soil organic matter (SOM) (e.g. Cely et al. 2014; Maestrini et al. 2014), and enhanced concentrations of PyOM in soil also could influence a forest’s C budget by promoting the retention of SOM (e.g. Whitman et al. 2014). However, neither of these phenomena constitutes a C sink. Even if PyOM promotes SOM retention and thus mitigates soil CO2 emissions, it does not remove CO2 from the atmosphere. The formation of PyOM deserves concerted study because of its potential influence on SOM cycling. However, the formation of PyOM does not remove CO2 from the atmosphere, even if more of it has formed in recent decades, and PyOM is not a missing C sink for atmospheric CO2.
This article is protected by copyright. All rights reserved.
Accepted Article
References Cely P, Tarquis AM, Paz-Ferreiro J et al. (2014) Factors driving the carbon mineralization priming effect in a sandy loam soil amended with different types of biochar. Solid Earth, 5, 585-594. Kasischke EA, Verbyla DL, Rupp TS et al. (2010) Alaska’s changing fire regime – implications for the vulnerability of its boreal forests. Canadian Journal of Forest Research, 40, 1313-1324. Maestrini B, Hermann AM, Nannipieri P et al. (2014) Ryegrass-derived pyrogenic organic matter changes organic carbon and nitrogen mineralization in a temperate forest soil. Soil Biology and Biochemistry 69, 291-301. Santín C, Doerr SH, Preston CM, González-Rodríguez G (In press) Pyrogenic organic matter production from wildfires: a missing sink in the global carbon cycle. Global Change Biology. Schlesinger WH, Bernhardt ES (2013) Biogeochemistry: An analysis of global change. Academic Press, New York. Whitman T, Enders A, Lehmann J (2014) Pyrogenic carbon additions to soil counteract positive priming of soil carbon mineralization by plants. Soil Biology and Biochemistry 73, 33-41.
This article is protected by copyright. All rights reserved.
Received Date : 05-Dec-2014 Accepted Date : 08-Dec-2014 Article type
: Letters to Editor
Corresponding author email id : [email protected]
Letter to the Editor on “Pyrogenic organic matter production from wildfires: a missing sink in the global carbon cycle”
Sharon A. Billings1, William H. Schlesinger2
1
Department of Ecology and Evolutionary Biology and Kansas Biological Survey, University of Kansas,
Lawrence, KS, USA 2
Cary Institute of Ecosystem Studies, Millbrook, NY 12545
Santín et al. (2014) report the conversion of different boreal forest biomass pools to pyrogenic organic matter (PyOM) during a forest fire, and suggest that ~100 Tg C y-1 may be converted to PyOM in boreal forests globally. They further suggest that PyOM formation represents a missing C sink. The phrase ‘missing C sink’ derives from a lack of closure in the atmospheric C budget. Approximately ⅓ of the CO2 emitted to the atmosphere via burning of fossil fuels and land use change cannot be accounted for after oceanic uptake and atmospheric accumulations are tallied (Schlesinger and Bernhardt 2013). To resolve the C budget, we must identify processes that 1) draw a meaningful quantity of CO2 out of the atmosphere, and 2) have increased their rate of CO2 capture since CO2 emissions from fossil fuels and land use change became important features of Earth’s C
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/gcb.12836 This article is protected by copyright. All rights reserved.
Accepted Article
cycle. The second criterion, perhaps less intuitive than the first, is critical: because atmospheric [CO2] was relatively constant for over 10,000 years of the Holocene, identifying a modern C sink does nothing to resolve Earth’s C budget if we cannot also demonstrate that the sink did not exist, or functioned at a reduced rate, prior to the Industrial Revolution. The formation of PyOM does not meet either criterion.
First, the formation of PyOM, regardless of the rate, does not remove CO2 from the atmosphere. When fire generates PyOM, regardless of the persistence of the resulting material, the process represents a transformation of one type of fixed C (biomass) into another (PyOM). As such, there is no direct effect of PyOM generation on atmospheric CO2. Second, PyOM has been forming in boreal forest soils for 1000s of years during which atmospheric CO2 was stable. Though the area of boreal forest subjected to burning apparently has increased in recent decades (Kasischke et al. 2010), there is no evidence that the increased burned area translates to enhanced rates of CO2 capture from the atmosphere via forest productivity. Some studies suggest that PyOM may promote short-term decay of soil organic matter (SOM) (e.g. Cely et al. 2014; Maestrini et al. 2014), and enhanced concentrations of PyOM in soil also could influence a forest’s C budget by promoting the retention of SOM (e.g. Whitman et al. 2014). However, neither of these phenomena constitutes a C sink. Even if PyOM promotes SOM retention and thus mitigates soil CO2 emissions, it does not remove CO2 from the atmosphere. The formation of PyOM deserves concerted study because of its potential influence on SOM cycling. However, the formation of PyOM does not remove CO2 from the atmosphere, even if more of it has formed in recent decades, and PyOM is not a missing C sink for atmospheric CO2.
This article is protected by copyright. All rights reserved.
Accepted Article
References Cely P, Tarquis AM, Paz-Ferreiro J et al. (2014) Factors driving the carbon mineralization priming effect in a sandy loam soil amended with different types of biochar. Solid Earth, 5, 585-594. Kasischke EA, Verbyla DL, Rupp TS et al. (2010) Alaska’s changing fire regime – implications for the vulnerability of its boreal forests. Canadian Journal of Forest Research, 40, 1313-1324. Maestrini B, Hermann AM, Nannipieri P et al. (2014) Ryegrass-derived pyrogenic organic matter changes organic carbon and nitrogen mineralization in a temperate forest soil. Soil Biology and Biochemistry 69, 291-301. Santín C, Doerr SH, Preston CM, González-Rodríguez G (In press) Pyrogenic organic matter production from wildfires: a missing sink in the global carbon cycle. Global Change Biology. Schlesinger WH, Bernhardt ES (2013) Biogeochemistry: An analysis of global change. Academic Press, New York. Whitman T, Enders A, Lehmann J (2014) Pyrogenic carbon additions to soil counteract positive priming of soil carbon mineralization by plants. Soil Biology and Biochemistry 73, 33-41.
This article is protected by copyright. All rights reserved.
