Opportunities and challenges for savanna burning emissions abatement in southern Africa

Russell‐Smith, Jeremy; Yates, Cameron; Vernooij, Roland; Eames, Tom; Werf, Guido R. van der; Ribeiro, Natasha; Edwards, Andrew C.; Beatty, Robin; Lekoko, Othusitse; Mafoko, Jomo; Monagle, Catherine; Johnston, Sam

doi:10.1016/j.jenvman.2021.112414

Cited by 41 publications

(64 citation statements)

References 97 publications

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“…We must note, however, that the date chosen for the EDS of Russell-Smith et al ( 2021) is more comparable with the MDS date used in our study -both dates represent the "middle" of the dry season. Indeed, as Russell-Smith et al (2021) note, trees in wooded savanna had already begun dropping leaves, and grasses were fully cured at the time of their "EDS" fires -characteristics we would not associate with early burning in West Africa. As such, we would argue that Russell-Smith et al (2021) provide good evidence that MDS (not EDS) fires produce lower methane emissions than LDS fires in Africa.…”

Section: Discussionmentioning

confidence: 96%

“…Indeed, one study in Africa found that the bulk of CH 4 emissions come from EDS fires (Hoffa et al, 1999) because the decrease in area burned is more than offset by the increase in the CH 4 EF. Elsewhere in southern Africa, Russell-Smith et al (2021) found that emission factors varied significantly by season for some vegetation types but not others, although notably the latter study involved only "cured" grasses. We would argue that "early" fires burn uncured fuels by definition.…”

Section: Introductionmentioning

confidence: 84%

“…Indeed, African savanna fires regularly burn such large areas that they are visible from space, so much so that NASA scientists refer to Africa as the "burn center of the planet" (National Aeronautics and Space Administration, 2005). Savanna fires are a major source of greenhouse gases (GHGs) including carbon dioxide, carbon monoxide, methane and nitrous oxide (Koppmann et al, 2005;Russell-Smith et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Critically, most studies of emissions are global scale and use average biome level EFs. EFs show large variability, however, between and within biomes due to differences in fuel type and composition, burning conditions, and tree density (Andreae and Merlet, 2001;Korontzi, 2005;van Leeuwen and van der Werf, 2011;Russell-Smith et al, 2021). There are few regionally specific emission estimates because accurate quantification of such emissions is difficult, being dependent upon reliable estimation of the various parameters, many of which require intense fieldwork (Russell-Smith et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Methane gas emissions from savanna fires: what analysis of local burning regimes in a working West African landscape tell us

et al. 2021

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Abstract. Savanna fires contribute significantly to greenhouse gas emissions. While it is recognized that these fires play a critical role in the global methane cycle, there are too few accurate estimates of emissions from West Africa, the continent's most active fire region. Most estimates of methane emissions contain high levels of uncertainty as they are based on generalizations of diverse landscapes that are burned by complex fire regimes. To improve estimates we used an approach grounded in the burning practices of people who set fires to working landscapes. We collected and analyzed smoke samples for 36 experimental fires using a canister method for the early dry season (EDS) and mid-dry season (MDS). We also collected data for savanna type, grass type, biomass composition and amount consumed, scorch height, speed of fire front, fire type, and ambient air conditions for two sites in Mali. We report values for fire intensity, combustion completeness, patchiness, modified combustion efficiency (MCE), emission factor (EF) and methane emission density. Our study found that mean methane EFs ranged from 3.83 g kg−1 in the EDS to 3.18 g kg−1 in the MDS, but the small sample did not provide enough power for this effect to be significant. We found head fires had nearly double the CH4 EF of backfires (5.12 g kg−1 to 2.74), a significant difference. Byram's fire intensity was a significant driver of CH4 EF but with weak effect. Methane emission density increased marginally from 0.839 g m−2 in the EDS to 0.875 g m−2 in the MDS, a difference that was not significant. Head fires, however, had much higher emission densities than backfires – 1.203 vs. 0.708 g m−2 – respectively, a significant difference. We suggest the reason for the higher methane emissions from head fires, which have higher intensity, is the longer flame lengths that burn green leaves on trees, releasing methane. We conclude that policies aimed at shifting the burning regime earlier to reduce methane emissions will not have the desired effects, especially if fire type is not considered. Future research should consider the state and amount of leafy biomass combusted in savanna fires.

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Methane gas emissions from savanna fires: what analysis of local burning regimes in a working West African landscape tell us

et al. 2021

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“…The neighbourhood of south-central Africa was chosen as the test site due to high incidence of fires in the region. Savannah fires in sub-Saharan Africa in the Southern Hemisphere contribute nearly a third (29 %) of global fire emissions (Russell-Smith et al, 2021). During the dry seasons, lasting roughly from spring to autumn, a big part of south-central Africa is filled with fires which are quite evenly distributed throughout the region of a size about one third of Europe.…”

Section: Test On Regularly Ignited Fires In African Savannahsmentioning

confidence: 99%

Forecasting the regional fire radiative power for regularly ignited vegetation fires

Partanen

Sofiev

2021

Preprint

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Abstract. This paper presents a phenomenological framework for forecasting the area-integrated fire radiative power from wildfires. In the method, a region of interest is covered with a regular grid, which cells are uniquely and independently parameterized with regard to the fire intensity according to (i) the fire incidence history, (ii) the retrospective meteorological information, and (iii) remotely-sensed high temporal resolution fire radiative power taken together with (iv) consistent cloud mask data. The parameterization is realized by fitting the predetermined functions for diurnal and annual profiles of fire radiative power to the remote-sensing observations. After the parametrization, the input for the fire radiative power forecast is the meteorological data alone, i.e., the weather forecast. The method is tested retrospectively for south-central African savannah areas with grid cell size of 1.5° × 1.5°. The input data included ECMWF ERA5 meteorological reanalysis and SEVIRI/MSG Fire Radiative Power and Cloud Mask. It has been found that in the areas with large numbers of wildfires regularly ignited on a daily basis during dry seasons from year to year, the temporal fire radiative power evolution is quite predictable, whereas the areas with irregular fire behaviour predictability was low. The predictive power of the method is demonstrated by comparing the predicted fire radiative power patterns and fire radiative energy values against the corresponding remote-sensing observations. The current method showed good skills for the considered African regions and was useful in understanding the challenges in predicting the wildfires in a more general case.

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Using a demographic model to project the long‐term effects of fire management on tree biomass in Australian savannas

Murphy

Whitehead

Evans

et al. 2023

Ecological Monographs

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Tropical savannas are characterized by high primary productivity and high fire frequency, such that much of the carbon captured by vegetation is rapidly returned to the atmosphere. Hence, there have been suggestions that management‐driven reductions in savanna fire frequency and/or severity could significantly reduce greenhouse gas emissions and sequester carbon in tree biomass. However, a key knowledge gap is the extent to which savanna tree biomass will respond to modest shifts in fire regimes due to plausible, large‐scale management interventions. Here, we: (1) characterize relationships between the frequency and severity of fires and key demographic rates of savanna trees, based on long‐term observations in vegetation monitoring plots across northern Australia; (2) use these relationships to develop a process‐explicit demographic model describing the effects of fire on savanna tree populations; and (3) use the demographic model to address the question: to what extent is it feasible, through the strategic application of prescribed burning, to increase tree biomass in Australian tropical savannas? Our long‐term tree monitoring dataset included observations of 12,344 tagged trees in 236 plots, monitored for between 3 and 24 years. Analysis of this dataset showed that frequent high‐severity fires significantly reduced savanna tree recruitment, survival, and growth. Our demographic model suggested that: (1) despite the negative effects of frequent high‐severity fires on demographic rates, savanna tree biomass appears to be suppressed by only a relatively small amount by contemporary fire regimes, characterized by a mix of low‐ to high‐severity fires; and (2) plausible, management‐driven reductions in the frequency of high‐severity fires are likely to lead to increases in tree biomass of about 11.0 t DM ha−1 (95% CI: −1.2–20.8) over a century. Accounting for this increase in carbon storage could generate significant carbon credits, worth, on average, three times those generated annually by current greenhouse gas (methane and nitrous oxide) abatement projects, and has the potential to significantly increase the economic viability of fire/carbon projects, thereby promoting ecologically sustainable management of tropical savannas in Australia and elsewhere. This growing industry has the potential to bring much‐needed economic activity to savanna landscapes, without compromising important natural and cultural values.

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Opportunities and challenges for savanna burning emissions abatement in southern Africa

Cited by 41 publications

References 97 publications

Methane gas emissions from savanna fires: what analysis of local burning regimes in a working West African landscape tell us

Methane gas emissions from savanna fires: what analysis of local burning regimes in a working West African landscape tell us

Forecasting the regional fire radiative power for regularly ignited vegetation fires

Using a demographic model to project the long‐term effects of fire management on tree biomass in Australian savannas

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