Effect of charcoal production and woodland type on soil organic carbon and total nitrogen in drylands of southern Mozambique

Abstract

African woodland ecosystems function as important reservoirs for soil organic carbon (SOC) and total nitrogen (TN). However, these ecosystem functions are particularly sensitive to social-ecological factors, the impacts of which remain understudied. Here, we examine how vegetation type and charcoal production affect SOC and TN in dry woodlands of southern Africa, focusing on three woodland ecosystems that represent the main types in southern Mozambique: Androstachys forest, Combretum woodland and Mopane woodlands. Drawing on data from soil surveys at 0-5 cm and 0-30 cm depth in different vegetation types and both distant from and proximate to sites of active charcoal production, we estimate that woodlands in Mabalane District store on average 19 ± 10 (± SE) Mg ha-1 of SOC, and 2.2 ± 0.9 Mg ha-1 of TN at 0-30 cm, significantly lower than values reported for other Miombo woodlands in the region. Our analysis shows that woodland type does not directly influence the amount of SOC and TN stored in soil, and that soil proximate to charcoal kilns had twice the amount of SOC (30.0 ± 1.8 Mg ha-1) and TN (4.5 ± 0.5 Mg ha-1) compared with non-charcoal plots. This study adds to our understanding of the impact of charcoal production on soil SOC and TN in dry woodlands of southern Africa, and demonstrates some localised impacts of charcoal production. We discuss the implications of our findings in the light of emerging carbon-based payments for ecosystem services programmes in the region.

The effect of charcoal production on carbon cycling in African biomes

“…Finally, for savannas, we find a similar pattern as for historical charcoal regimes, and we interpret these results with the ability of savanna biomes to be more resilient to disturbances (Osborne et al, 2018; Pelletier et al, 2018; Tredennick & Hanan, 2015). For all biomes, we find little change in soil carbon, with a small increase in soil carbon stocks right after charcoal production, and this agrees with results from field studies in the savanna of Mozambique (Lisboa et al, 2020). The small increase in soil carbon is due to biomass residues during charcoal production, which later enter soil carbon stocks due to increased decomposition (Miao et al, 2019).…”

Allometric equations and height-diameter models for estimating above-and below-ground biomass of Colophospermum mopane J.Léonard. in Mozambique

“…The climate in this area is classified as semi-arid, with an average annual rainfall of 505 mm/year and an average annual temperature of 24 °C. The region experiences distinct dry and wet seasons, with most precipitation between October and April 32 . The vegetation in the Mabalane District primarily consists of Mopane woodlands (Colophospermum mopane (Benth.)…”

“…Gilg & Gilg-Ben. 32 . The second study site is in Tambara District, situated in the central region of Mozambique in Manica province (Figure 1).…”

Biochar’s effect on the ecosystem services provided by sandy-textured and contaminated sandy soils: a systematic review protocol

“…However, black carbon and charcoal can differ from biochar in production and application purposes. For instance, black carbon can be made by burning fossil fuels as well as biomass [55], while charcoal is produced mainly to provide affordable energy to rural areas and is not used solely as a soil amendment [56]. However, we do include the terms "black carbon" and "charcoal" in the intervention search terms (Table 2).…”