Effects of vegetation zones and climatic changes on fire-induced atmospheric carbon emissions: a model based on paleodata

Abstract

Abstract. An original method is proposed for estimating past carbon emissions from fires in order to understand longterm changes in the biomass burning that, together with vegetation cover, act on the global carbon cycle and climate. The past carbon release resulting from paleo-fires during the Holocene is examined using a simple linear model between measured carbon emissions from modern fires and sedimentary charcoal records of biomass burning within boreal and cold temperate forests in eastern Canada (Quebec, Ontario). Direct carbon emissions are estimated for each ecozone for the present period and the fire anomaly per kilo annum (ka) v. present day (0 ka) deduced from charcoal series of 46 lakes and peats. Over the postglacial, the Taiga Shield ecozone does not match the pattern of fire history and carbon release of Boreal Shield, Atlantic Maritime, and Mixedwood Plains ecozones. This feature results from different air mass influences and the timing of vegetation dynamics. Our estimations show, first, that the contribution of the Mixedwood Plains and the Atlantic Maritime ecozones on the total carbon emissions by fires remains negligible compared with the Boreal Shield. Second, the Taiga Shield plays a key role by maintaining important carbon emissions, given it is today a lower contributor.

Charcoal dispersion and deposition in boreal lakes from 3 years of monitoring: Differences between local and regional fires

“…Sediment‐based fire history reconstructions can inform on long‐term fire‐climate‐vegetation interactions in diverse ecosystems [ Aleman et al ., ; Ali et al ., ; Mooney et al ., ]. This information is useful to guide future management decisions [ Bergeron et al ., ; Oris et al ., ] or to understand biogeochemical cycles [ Bremond et al ., ; van Bellen et al ., ]. An oft‐used method to reconstruct spatially explicit fire histories involves the numerical analysis of continuous macroscopic charcoal (>120–150 µm) accumulation records (CHAR) with the so‐called “decomposition approach” that aims at separating charcoal records into a “peak component” and a “background component” [ Clark and Royall , ; Long et al ., ].…”

Paleofire reconstruction based on an ensemble‐member strategy applied to sedimentary charcoal

“…Sedimentary charcoal records have proven useful for identifying long‐term trends in fire activity at local to global scales, studying interactions with vegetation [ Clark , ; Blarquez and Carcaillet , ] and the role of biomass burning in the carbon cycle [ Clark et al ., ; Bremond et al ., ], and understanding the linkages with climatic changes [ Whitlock et al ., ; Marlon et al ., ; Ali et al ., ; Nelson et al ., ]. Information contained in sedimentary charcoal records may reflect three different components: (i) amount of biomass burned (i.e., long‐term trends in Charcoal Accumulation Rate (CHAR) or “background” trends) [ Marlon et al ., ; Higuera et al ., ], (ii) fire frequency [ Gavin et al ., ], and (iii) noise [ Carcaillet et al ., ].…”

Wildfires in boreal ecosystems: past, present and some emerging trends

“…These forests therefore appear, at some level, to be resilient to changes in fire activity . Nonetheless, even though fire is a long-term intrinsic property of the boreal forest (Bremond et al 2010;Carcaillet et al 2010;Higuera et al 2010), its occurrence is increasingly linked with human activities (Marlon et al 2008;Bradshaw et al 2010;Niklasson et al 2010;Wang and Anderson 2010). This influence has up until now been direct, via ignition, but the indirect influence through human-induced climate change is becoming worrisome (Flannigan et al 2009;Bergeron et al 2010;Metsaranta 2010).…”

“…These advances include reconstructions from fire-scarred trees, stand establishment records, tree rings, charcoal particles preserved in lake sediments, peat-bog and soil deposits, and ammonium concentration [NH 4þ ] in ice cores (see Whitlock et al 2010b for an overview of paleofire research). The first four papers of this issue (Bradshaw et al 2010;Bremond et al 2010;Carcaillet et al 2010;Higuera et al 2010) report on analyses of sedimentary charcoals preserved in lake sediments, whereas the last paper on this topic (Niklasson et al 2010) is based on dendrochronological analysis.…”

“…The work by Higuera et al (2010) notably provides a historical and critical overview of the statistical techniques used for filtering out fire signals from the background noise in sedimentary charcoal records, and concludes with sound recommendations for follow-up studies. The study by Bremond et al (2010) addresses the question of carbon emissions from fires and proposes an original method for the estimation of such quantity based on sedimentary charcoal records, with an application to eastern boreal Canada. Biomass combustion is one of the most important elements in global carbon flux processes, and yet very few attempts have been made to estimate the past rate of carbon releases into the atmosphere through paleo-biomass burning (Carcaillet et al 2002).…”