Global Pyrogenic Carbon Production During Recent Decades Has Created the Potential for a Large, Long‐Term Sink of Atmospheric CO₂

Abstract

Fires play an important role in the terrestrial biosphere carbon cycle, not only through direct carbon release but also contributing to a potential long-term storage as pyrogenic carbon (PyC). PyC is formed through fires, and, because it may resist further biological and chemical degradation, is more stable in soil and sediment than original biomass. At the global scale, contributions of fires to both atmospheric CO 2 emissions and PyC accumulation are potentially large but difficult to estimate. Our analysis was based on existing simulation results from two different modeling approaches (Global Fire Emissions Database version 4 [GFED4s] and Terrestrial Ecosystem Model version 6 [TEM6]) that used global area burned data to provide recent, retrospective estimates of CO 2 emissions from vegetation combustion, together with published, biome-and continental-scale conversion ratios that relate CO 2 emissions to PyC production (PyC/CO 2 ) during combustion. The estimates of global CO 2 emissions from fires differed substantially between the two models' results. GFED4s estimated 2,041 Tg C/year during the 2000-2016 time period, whereas the TEM6 estimate was considerably lower at 643 Tg C/year from 2000 to 2010. Global PyC production estimates from fires were 153.4 ± 18.7 and 49.5 ± 4.9 Tg C/year based on the emission estimates from GFED4s and TEM6, respectively. Our results suggest that African tropical savanna fires produced the largest amount of CO 2 emissions and PyC among global biomes, the most significant interannual variations in CO 2 emissions and PyC production were found in tropical forests, and the magnitude of PyC produced by fires each year represented a potentially significant long-term sink of atmospheric CO 2 .

Du Feu à l'Eau: Source and Flux of Dissolved Black Carbon From the Congo River

“…Although the conversion of non‐woody fuels to BC is less efficient, about 80% of BC produced within the margins of the Congo River Basin is derived from savannah, grassy‐type biomass, based upon current carbon emissions (Van Der Werf et al, 2017) and BC production estimates (Jones, Santín, et al, 2019) for the region. This agrees with earlier modeling efforts which show African savannah fires to be a significant source of fire‐derived carbon on a global scale (Wei et al, 2018). The Congo River exports an estimated 1.4 Tg‐C as DBC plus PBC each year (Table 1, Coppola et al, 2018), which suggests that the production of BC in the basin exceeds the amount of BC removed annually by the Congo River by an order of magnitude.…”

Pyrogenic Carbon Generation From Fire and Forest Restoration Treatments

“…Importantly, there is little consistency between individual studies and the method employed to estimate PyC content generated during fire events, therefore the PyC production rate across studies was highly variable which creates challenges, particularly when modeling at larger spatial scale (Wei et al, 2018). By compiling published data of soil PyC content in the whole soil profile to estimate global PyC stock across a variety of environmental constraints (e.g., climate, soil pH, site net primary production), Reisser et al (2016) found that soil properties, rather than fire characteristics best explained PyC content at global scales where high clay soils (clay content over 50%) and alkaline soils had more PyC content than low clay soils and acidic soils.…”

“…Recent studies have pointed to PyC generation as offsetting C emissions during wildfire (Wei et al, 2018;Jones et al, 2019) requiring us to further assess the influence of fire on the global C balance. Importantly, these studies demonstrate that PyC accumulation in ecosystems is most directly related to fire severity and frequency (Sawyer et al, 2018;Adkins et al, 2019).…”

Functional Ecology of Forest, Heath, and Shrub Savannah Alternate States in Eastern Canada

“…This is consistent with pyrogenic organic matter resulting from incomplete combustion of organic matter in heath and wood savanna leading to lower available N, which subsequently lowers the C:N ratio and immobilizes N [43]. Charcoal (pyrogenic carbon) from forest fires has been shown to change soil pH [44] and produce a significant long-term carbon sink [45,46]. Moreover, past research [47] has shown that the abundance of ericaceous plants, such as Kalmia, is negatively correlated with soil ammonium and phosphorus contents, leading to limitations in soil nutrient availability.…”