Mopane Woodland Research Articles

Experiences of ecosystem changes on food services of mopane woodland communities in Vhembe, South Africa

Mopane woodlands have been shifting. While it is important to understand the spatial patterns that characterise this phenomenon, it is even more important to understand the impacts of shifting Mopane woodlands on rural communities that rely on them. This study sought to establish the impacts of shifting mopane woodlands on the production of indigenous plant food in Ward 12 of Musina local municipality in the Vhembe District municipality in the Limpopo province of South Africa. To accomplish this, the study utilised a hybrid inductive approach involving thematic-based questionnaire interviews and an exploratory view to gain insight into the narratives of focus group participants. Results revealed that seven (7) out of eleven (11) indigenous plant foods are becoming extinct, thereby limiting food sources of indigenous and local people who used to rely on them. The spatial pattern of the plant foods that are still available has now changed as they no longer grow within the reach of local communities. The community members are struggling to adapt to these changes. From these observations, we recommend that local and regional levels’ policies related to natural resource management should consider the unique challenges faced by communities experiencing disruptive ecosystem changes and provide the necessary support for sustainable adaptation.

Emergent trees in Colophospermum mopane woodland: influence of elephant density on persistence versus attrition.

Colophospermum mopane (mopane) forms mono-dominant woodlands covering extensive areas of southern Africa. Mopane provides a staple foodstuff for elephants, who hedge woodland by reducing trees to small trees or shrubs, leaving emergent trees which are too large to be pollarded. Emergent trees are important for supporting faunal biodiversity, but they can be killed by ringbarking. This study first examined the influence of elephant density on woodland transformation and the height distribution of canopy volume, and, second, whether canopy volume is maintained, and tall emergent trees too large to be broken can persist, under chronic elephant utilisation. Three regimes of 0.23, 0.59 and 2.75 elephants km-2 differed in vegetation structure and the height structure of trees. Areas under the highest elephant density supported the lowest total canopy volume owing to less canopy for plants >3 m in height, shorter trees, loss of most trees 6-10 m in height, but trees >10 m in height (>45 cm stem diameter) persisted. Under eight years of chronic utilisation by elephants, transformed mopane woodland maintained its plant density and canopy volume. Plant density was greatest for the 0-1 m height class, whereas the 3.1-6 m height class provided the bulk of canopy volume, and the 1.1-3 m height layer contained the most canopy volume. Emergent trees (>10 m in height) suffered a loss of 1.4% per annum as a result of debarking. Canopy dieback of emergent trees increased conspicuously when more than 50% of a stem was debarked, and such trees could be toppled by windthrow before being ringbarked. Thus relict emergent trees will slowly be eliminated but will not be replaced whilst smaller trees are being maintained in a pollarded state. Woodland transformation has not markedly reduced canopy volume available to elephants, but the slow attrition of emergent trees may affect supported biota, especially cavity-dependent vertebrate species, making use of these trees.

Dynamics of land-cover change and characterization of charcoal production and trade in southwestern Angola

Miombo and mopane woodlands of southwestern Angola have been overexploited for decades, leading to deforestation and forest degradation driven by social dynamics during and after the civil war (1975–2002), with different patterns of use of natural resources. Our objective was to study the changes in land-cover in three municipalities of southwestern Angola, and to characterize the charcoal production and trade on miombo and mopane woodlands, where that production was identified as one of the main causes of degradation. Land-cover dynamics between 1990 and 2019 was evaluated based on four land-cover maps, and the processes involved in deforestation and forest degradation were identified and discussed. Roadside charcoal sale locations, markets, the most exploited species, and the type, size, and efficiency of the kilns were assessed through field surveys. Between 1990 and 2019, the woodland area decreased and was converted to savanna woodland and agriculture, while the urban area continuously increased. Both miombo and mopane woodlands went through higher annual deforestation rates than those reported by FAO at the national level. The dynamics of land use were different between the war and post-war periods, respectively with the abandonment of agricultural land and migration of rural populations to the cities, and their return to the countryside and use of land and forest resources as primary subsistence activities. Agriculture and charcoal production were identified as the main income-generating activities, and the occupation of unused land by outsiders may have also contributed to intensify deforestation and forest degradation. To slow down the ongoing area loss of miombo and mopane woodlands, it seems crucial to implement conservation and restoration strategies promoting the sustainable use of the resources while ensuring the provision of essential goods to local populations and contributing to reduce poverty.

Spatio-temporal usage of water sources by Black-cheeked Lovebirds Agapornis nigrigenis: implications for conservation planning

Summary The Black-cheeked Lovebird Agapornis nigrigenis has a highly restricted range in dry south-western Zambia, where its distribution is clumped and localised in association with mopane Colophospermum mopane woodland and permanent water pools. Fieldwork and monitoring over 30 months between December 2018 and October 2021 established that the lovebirds’ usage of pools for drinking was higher towards the centre of the bird’s distribution and influenced by the pools’ proximity to mopane woodlands, surrounding tree cover, and level of human activity. Of the four pool types available for use by lovebirds (i.e. mopane, grassland, river, and artificial), mopane and grassland pools were disproportionally susceptible to drying out in the dry season, hence showed greater variation in numbers of visiting birds compared with the other two types. Lovebirds showed a preference for pools with a perimeter of <50 m and tended to avoid those with a perimeter >100 m, consistent with a positive association between pool size and human activity. Convergence between humans and lovebirds in dependence on water resources and mopane woodland points to the need to find ways to overcome potential conflicts. Such ways include creating small, shallow-sided, undisturbed pools in or near mopane woodland, extending water retention in existing mopane pools, and enhancing the capacity of artificial pools to meet the needs of the lovebirds.

Are Mopani Worms a Mechanism for Mopane Tree (Colophospermum mopane) Conservation? An Evaluation of the Villages Around Giyani, Limpopo Province, South Africa

Background and Background Aims Colophospermum mopane provides many benefits including mopani worms, firewood, timber for construction, and medicine. Despite C. mopane playing a significant role in the lives and livelihoods of communities within their range, they are destroyed because of unsustainable harvesting practices coupled with lack of management practices. Assessment of people’s attitudes has become significant in studies dealing with the conservation of biodiversity. This study aims to assess the attitudes of local communities in and surrounding Giyani in Limpopo Province in South Africa towards the mopane tree and to determine if their attitudes relate to obedience to traditional rules and regulations. Methods Interview-administered questionnaires were used to systematically select 161 households in Muyexe village and 82 households in Nsavulani village. The questionnaire evaluated the biographical data of respondents, knowledge of mopane woodlands, importance of mopane trees and mopani worms, and their attitudes towards mopane tree conservation. Results The overwhelming majority of respondents in both villages had positive attitudes towards mopane trees for ethical reasons. Respondents were also positive that mopane trees should be protected for future generations. The positive attitude of most respondents relates to obedience to rules and regulations that do not allow cutting of wet C. mopane. Respondents only cut dead or dry mopane woodlands for fuelwood. Cutting or harvesting was done on a subsistence and sustainable basis. Conclusion The communities have shown that they are guardians of C. mopane. The study concluded that mopani worms serve a mechanism for C. mopane conservation in Muyexe and Nsavulani villages in South Africa. Implications for conservation The positive attitudes of local communities, and obedience to the customary rules and regulations is a positive sign not only for ethical reasons, but also for long-term mopane woodlands conservation. This approach encourages the long sustainability of mopane woodlands in the study area.

Assessing the Impact of Charcoal Production on Southern Angolan Miombo and Mopane Woodlands

About 80% of Angola’s forest surface is covered by Miombo and Mopane woodlands, which are explored for diverse activities such as fuelwood and food. This study aimed to assess the recovery dynamics of Miombo and Mopane woodlands after the selective cutting of tree species for charcoal production. For that, the structure and composition of plant communities in 37 plots, located in southwestern Angola, were characterized in fallows of different ages. Results showed that the diameter at breast height, basal area, biomass, and biovolume of trees all rose as the age of the fallow increased, and there were no significant differences in richness, diversity, or dominance of trees between adult–young classes or recent–older fallows. In Mopane, fallows took longer to regenerate, were more affected by environmental and anthropogenic factors, and also presented a higher species adaptation to disturbance. There were more sprouter and seeder trees in Miombo, and new kilns were more distant from roads and villages. Moreover, the selective removal of species deeply altered the community structure and dynamics, despite not directly affecting tree diversity. Thus, new management strategies are needed to ensure the survival of these woodlands such as expanding protected areas and increasing systematic research.

Mopane (Colophospermum mopane): A potential winner under climate change in southern Africa

AbstractDistribution and abundance under climate change of particularly non‐timber forest product tree species is vital since they sustain many livelihoods, especially in rural sub‐Saharan Africa. The aim of the study was to determine the current and future natural range of mopane (Colophospermum mopane (J. Kirk ex Benth.) J. Léonard, Fabaceae), a dominant tree species in mopane woodlands of southern Africa. An ensemble model was built in ‘biomod2’ from eight algorithms and used to estimate the current and future distribution. Seven bioclimatic variables and 269 occurrence records were used to calibrate individual models that were later combined into an ensemble model. The ensemble model was projected to two time periods, 2041–2060 and 2081–2100, under two shared socio‐economic pathways (SSPs), SSP2‐4.5 and SSP5‐8.5, and three general circulation models (GCMs). The ensemble model showed high performance (KAPPA = 0.770, ROC = 0.961, TSS = 0.792, ACCURACY = 0.900). A map of the current distribution shows occurrence predominantly in low‐lying areas, including the Zambezi, Save and Limpopo valleys, Okavango and Cuvelai basins, and in southern and central Mozambique. Projection maps show expansion under all SSPs, GCMs and time periods. Averaged across GCMs in 2041–2060, the range expanded by 22.37% under SSP2‐4.5, and by 19.94% under SSP5‐8.5. In 2081–2100, the range expanded by 20.43% under SSP2‐4.5, and by 27.62% under SSP5‐8.5. Notably, the range expansion was highest under SSP5‐8.5, an SSP that envisages unmitigated greenhouse gas release and the largest mean global temperature increase. It is highly likely that mopane is not directly threatened by climate change. Indirect climate change threats, however, remain uncertain.

Integrating RADAR and optical imagery improve the modelling of carbon stocks in a mopane‐dominated African savannah dry forest

AbstractThis study examined the integration of two satellite data sets, that is Landsat 7 ETM+ and ALOS PALSAR (Advanced Land Observing Satellite Phased Array type L‐band Synthetic Aperture RADAR) in estimating carbon stocks in mopane woodlands of north‐western Zimbabwe. Mopane woodlands cover large spatial extents and provide ecosystem benefits to the rural economies and grazing resources for both livestock and wildlife. In this study, artificial neural networks (ANN) were used to estimate carbon stocks based on spectral metrics derived from Landsat 7 ETM+ and ALOS PALSAR. To determine the utility of the two satellite‐derived metrics, a two‐pronged modelling framework was adopted. Firstly, we used spectral bands and vegetation indices from the two satellite data sets independently, and subsequently, we integrated the metrics from the two satellite data sets into the final model. Results showed that the ALOS PALSAR (R2 = 0.75 and nRMSE = 0.16) and Landsat ETM+ (R2 = 0.78 and nRMSE = 0.14) derived spectral bands and vegetation indices comparatively yielded accurate estimations of carbon stocks. Integrating spectral bands and vegetation indices from both sensors significantly improved the estimation of carbon stocks (R2 = 0.84 and nRMSE = 0.12). These findings underscore the importance of integrating satellite data in vegetation biophysical assessment and monitoring in poorly documented ecosystems such as the mopane woodlands.

Implementing Local Climate Change Adaptation Actions: The Role of Various Policy Instruments in Mopane (Colophospermum mopane) Woodlands, Northern Namibia

The impacts of climate change are severe in rural communities because of their proximity to forest ecosystems. Colophospermum mopane woodlands are vital in supporting the livelihood of the rural communities in the mopane woodlands while contributing to biodiversity conservation. There is limited research regarding implementing policy instruments for climate change adaptation in rural areas of the mopane woodlands in northern Namibia. This study aims to investigate this subject from the mopane woodlands’ point of view to understand the implementation of policy instruments for climate change adaptation in the mopane woodlands. We conducted an online survey focusing on multiple stakeholders, experts in different sectors, and local communities. Major challenges such as a limited general understanding of climate change, its impacts, dry conditions of Namibia, and lack of funds for adaptation measures hamper the implementation of policy instruments for climate change adaptation in mopane woodlands. Policymakers and relevant stakeholders should emphasize altering rural communities’ reliance on forest resources for their livelihood by improving their awareness of the impacts of climate change. Future research should evaluate climate change policy instruments’ framework and strategies in the context of forest ecosystems at the rural area level of Namibia.

The influence of African elephants on litter and soil nitrogen attributes in mopane woodland in Hwange National Park, northwest Zimbabwe

Little is known about modification of nutrient fluxes through elephant-induced woodland change. We assessed litter quality, soil N attributes, and N transformations in five 20 × 20 m plots each established on sites of low, medium, and high elephant utilization categorized using dung-count surveys in three mopane woodland patches in Hwange National Park, Zimbabwe. Litter standing crop significantly declined but litter N, lignin, lignin:N, condensed tannins, and total phenols increased with increasing elephant utilization, peaking at intermediate levels of elephant utilization. Medium elephant utilization sites had more than twice the nitrate pools in low and high elephant utilization sites (p < 0.001). Ammonium concentration at low elephant utilization was lower by 65% and 92% than at high and medium elephant utilization, respectively. Soil moisture, infiltration rates, N mineralization, and nitrification decreased with increasing elephant utilization. Nitrogen mineralization and nitrification were up to four times greater in low than in medium and high elephant utilization sites. Ammonium, N mineralization, and nitrification were positively correlated to litter N but negatively correlated to condensed tannins. These results indicate that elephant-induced woodland change plays an important role in carbon and nutrient fluxes potentially increasing resources heterogeneity and reinforcing the patch dynamics of savanna.

Detection and genetic diversity of Mopeia virus in Mastomys natalensis from different habitats in the Limpopo National Park, Mozambique.

Mammarenaviruses have been a growing concern for public health in Africa since the 1970s when Lassa virus cases in humans were first described in west Africa. In southern Africa, a single outbreak of Lujo virus was reported to date in South Africa in 2008 with a case fatality rate of 80%. The natural reservoir of Lassa virus is Mastomys natalensis while for the Lujo virus the natural host has yet to be identified. Mopeia virus was described for the first time in M. natalensis in the central Mozambique in 1977 but few studies have been conducted in the region. In this study, rodents were trapped between March and November 2019in villages, croplands fields and mopane woodland forest. The aim was to assess the potential circulation and to evaluate the genetic diversity of mammarenaviruses in M. natalensis trapped in the Limpopo National Park and its buffer zone in Massingir district, Mozambique. A total of 534M. natalensis were screened by RT-PCR and the overall proportion of positive individuals was 16.9%. No significant differences were detected between the sampled habitats (χ2=0.018; DF=1; p=0.893). The Mopeia virus (bootstrap value 91%) was the Mammarenavirus circulating in the study area sites, forming a specific sub-clade with eight different sub-clusters. We concluded that Mopeia virus circulates in all habitats investigated and it forms a different sub-clade to the one reported in central Mozambique in 1977.

Marula (Sclerocarya birrea subsp. caffra, Anacardiaceae) thrives under climate change in sub‐Saharan Africa

AbstractClimate change threatens the persistence of some plant species, especially those highly adapted to their microclimates. The aim of the study was to determine the current suitable habitat of marula (Sclerocarya birrea subsp. caffra) and to forecast the habitat under different climate change scenarios. Predictions were made in Maxent using 490 occurrence records, four representative concentration pathways (RCPs) and three general circulation models (GCMs). Variables used were altitude, soil characteristics, monthly precipitation, monthly minimum and maximum temperatures and 19 bioclimatic variables. The current suitable habitat of marula largely occurs in mopane and dry miombo woodlands of southern Africa, including Madagascar. Permutation importance test showed that precipitation in November (30.1%), temperature seasonality (22.1%) and mean temperature of wettest quarter (14.3%) contributed significantly to the model of the current suitable habitat. When forecasted, the suitable habitat expanded under all GCMs and RCPs. On average in 2050, the range expanded by 26.0% (RCP2.6), 33.8% (RCP4.5), 24.8% (RCP6.0) and 42.3% (RCP8.5), while in 2070, it expanded by 30.0% (RCP2.6), 39.9% (RCP4.5), 33.3% (RCP6.0) and 45.1% (RCP8.5). The subspecies is not directly threatened by climate change, but indirect threats remain uncertain.

Dependência, pressão e recuperação de recursos florestais no Parque Nacional do Limpopo (Moçambique)

The general perception is that forest resources exploitation can cause the degradation and loss of resources and biodiversity, promoted by landscape fragmentation and pressure over habitats. But such assumption might not be adjusted to situations where long term exploitation by traditional communities is based on management strategies adapted to recovery, adjusting pressure to kept resources available. In this work, we assess the recovery of the Mopane woodlands considering different land use practices and stand development stages on areas explored by local communities. In detail, we want to explore: i) changes on stem size across plant comunities dominated by Mopane (Kirk ex Benth ex J. Leonard); ii) relationships between the variation in stem size across communities and the associated land use practices and vegetation stand development stage. To answer those questions, an inventory was carried out to collect data from 50 temporary circular plots of different sizes spatially nested, covering four stand development stages. Each nested circular plot was composed of a large plot (0.02 ha), an intermediate plot (0.04 ha), and an inner plot (0.01 ha) for counting stems of different DBH. Data was analysed using Excel, Two-Way Indicator Species Analysis (TWINSPAN) and CANOCO, and several parametric and non-parametric tests. TWINSPAN analysis, using stem counts, grouped the 1746 stems from 29 species (with Mopane as one species) into 5 communities and 10 sub-communities, based on indicator species and eigenvalues (level of stability). This study was carried out in the Limpopo National Park (LNP), in Mozambique, a conservation area established in 2001 and part of the Great Limpopo Transfrontier Park (GLTP) since 2002. Acording to the results, population structure (size class distribution of trees) of Mopane communities showed variation related to stand development stage, as expected. The initial stages show good regeneration, indicating that recovery is not hampered by the exploitation regime in use, a critical aspect once ecosystem dynamics of Mopane woodland has a deep influence on the way that local communities manage harvesting of Mopane products for different uses, and traditional uses do also have influence on recovery dynamics. So, management of such resource is critical to ensure sustainable resource use and guarantee provision for future generations. For that, a zonation of Mopane woodlands within the Park, considering different land uses, might enhance a quick system recovery on specific areas and contribute to woodland productivity, good quality products and reduce used areas, promoting habitat conservation.

Landscape habitat occupancy and distribution of the Wild Ground Pangolin (Smutsia temminckii) in Zimbabwe’s Protected Areas (PAs)

The Smutsia temminckii is the only species of pangolin known to exist in Zimbabwe and is considered vulnerable under the IUCN Red List of threatened species. Distribution of wild S. temminckii in protected areas (PAs) and associated environmental variables are not well defined in Zimbabwe. The study sort to relate key environmental variables (Altitude, rainfall, temperature and vegetation type) to habitat occupancy and distribution of S. temminckii. Data was collected from forty-eight stations based on S.temminckii sightings historical records spanning ten years (2011-2021) done by field rangers, tourists and scientific services research personnel. A review of available literature was done from online sources and station records. A distribution map based on S. temminckii sightings across various PAs in Zimbabwe was developed for this study. Results of this study reveal that S. temminckii occupy PAs in South East low-veld areas, Northwestern Zimbabwe, Mid Zambezi Valley and Nyanga NP. No historical data on S. temminckii sighting in central PAs located in ecological regions IIa, IIb and III of Zimbabwe. Climatic conditions associated with S. temminckii distribution, except for Nyanga NP, are average temperatures above 220C and rainfall between 400mm to 900mm per annum. Landscapes ideal for S. temminckii habitat occupancy have an altitude between 262m-2000m above sea level. Associated vegetation types for habitat occupancy of S. temminckii are the Zambezian and mopane woodlands as well as montane forest grasslands mosaic of Nyanga NP. Future studies should focus on establishing distribution of S. temminckii outside PA, population status and density to inform conservation of this rare and unique species around Zimbabwe.

The Occurrence and Characteristics of Imbrasia belina (Westwood, 1849) in the Subtropical Region of KwaZulu-Natal Province, South Africa

Mopane worm is the edible larva of Imbrasia (Gonimbrasia) belina (Westwood, 1894), a species of emperor moth that is generally found in central and southern African tropical regions. Both over-harvesting of larvae and the destruction of the mopane woodlands are threatening its biodiversity. An insect with a description matching that of I. belina was observed in the northern coastal region of KwaZulu-Natal, a subtropical biota. The aim of this study was to gain insight into the potential of the northern coastal region of KwaZulu-Natal as a sanctuary for I. belina. The presence of I. belina in the subtropical biota of the coastal region of KwaZulu-Natal was confirmed through mitochondrion CO1 gene sequences, this being so far its southernmost occurrence. Field surveys revealed the occurrence of four morphologically distinct variants within the uMkhanyakude District, inclusive of the protected iSimangaliso Wetland Park and Hluhluwe Game Reserve from the beginning of September to early November as do most of the populations in the mopane woodlands but differs from them by having one outbreak per season instead of two. Imbrasia belina is polyphagous and feeds off hosts including marula (Sclerocarya birrea [(A. Rich.) Hochst.] [Anacardiaceae]) and seven other tree species. There is therefore scope to use the northern KwaZulu-Natal coastal region as a sanctuary for biodiversity conservation of I. belina. There are initiatives to cultivate marula for its fruit in the region, which further increases the potential of the area as a sanctuary for I. belina by farming marula for both its fruit and I. belina. The protected nature reserves present in the region will ensure areas of controlled use by humans.

Functional heterogeneity of habitats and dry season forage variability in an Okavango Delta landscape, northern Botswana

The late dry season is a period when forage resources become limited in some African savannas that can induce a strong demographic bottleneck in herbivore populations with limited access to resource heterogeneity. This study determined forage quality and quantity between wetlands and drylands habitats during the late dry season. We subjectively sampled forage characteristics in four habitat types around the distal reaches of the Tsum Tsum floodplains of the Okavango Delta during the late dry season of 2015. The habitat types were mopane and sandveld woodland far from floodplains (two major dryland habitat types), sandveld habitats that receive soil moisture inputs from adjacent floodplains (wet sandveld) and sedgeland habitat within the floodplain. Leaves collected from forage in each habitat type were oven dried, milled and analysed for total nitrogen. Data of greenness, height, biomass and protein were analysed using Kruskal-Wallis test. Forage in wet sandveld had by far the highest protein content (~16%) of all habitat types but forage height and biomass were very low, whereas sedgelands had the highest biomass of adequate-quality forage, while dryland communities had the lowest quantity and quality of forage. Thus, foraging between a higher-biomass, adequate-quality reserve resource (sedgeland) and a high-quality but low-quantity bridging resource (wet sandveld) can help to ensure a balanced protein and fibre intake during the late dry season. Our study demonstrated the importance of wetland habitats for providing green forage with sufficient biomass and protein to sustain herbivores over the late dry season.

The connection between forest degradation and urban energy demand in sub-Saharan Africa: a characterization based on high-resolution remote sensing data

Charcoal is a key energy source for urban households in sub-Saharan Africa and charcoal production is the main cause of forest degradation across the region. We used multitemporal high-resolution remote sensing optical imagery to quantify the extent and intensity of forest degradation associated with charcoal production and its impact on forest carbon stocks for the main supplying area of an African capital. This analysis documents the advance of forest degradation and quantifies its aboveground biomass removals over a seven-year period, registering that, between 2013 and 2016, the average annual area under charcoal production was 103 km2 and the annual aboveground biomass removals reached 1081 000 (SD = 2461) Mg. Kiln densities in the study area rose to 2 kilns-ha, with an average of 90.7 Mg ha−1 of extracted aboveground biomass. Charcoal production was responsible for the degradation of 55.5% of the mopane woodlands in the study area between 2013 and 2019. We estimated post-disturbance recovery times using an ecosystem model calibrated for the study area. The simulations showed that recovery times could require up to 150 years for current aboveground biomass extraction rates. The results of the remote sensing analysis and the simulations of the ecosystem model corroborate the unsustainability of the present patterns of charcoal production. The detailed characterization of the spatial and temporal patterns of charcoal production was combined with household survey information to quantify the impact of the urban energy demand of the Maputo urban area on forest carbon stocks. The analysis shows that Maputo charcoal demand was responsible for the annual degradation of up to 175.3 km2 and that the contribution of the study area to this demand fluctuated between 75% and 33% over the study period. The extent, advance pace and distance from urban centers documented in this study support the idea that forest degradation from charcoal production cannot merely be considered a peri-urban process. The intensity of the aboveground biomass (AGB) removals and its contribution to forest carbon stocks changes is significant at the national and regional levels.

Monitoring intra and inter annual dynamics of forest degradation from charcoal production in Southern Africa with Sentinel – 2 imagery

The contribution of forest degradation to changes in forest carbon stocks remains poorly quantified and constitutes a main source of uncertainty in the forest carbon budget. Charcoal production is a major source of forest degradation in sub-Saharan Africa. We used multitemporal Sentinel-2 imagery to monitor and quantify forest degradation extent in the main supplying area of a major urban center of southern Africa over a 4-year period. We implemented an indirect approach combining Sentinel-2 imagery to map kiln and field measurements to estimate AGB removals and carbon losses from charcoal production. This work generated 10 m resolution maps of forest degradation extent from charcoal production in the study area at quarterly intervals from 2016–2019. These maps reveal an intense and rapid forest degradation process and expose the spatial and temporal patterns of forest degradation from charcoal production with high detail. The total area under charcoal production over the study period reached 26,647 ha (SD = 320.8) and the forest degradation front advanced 10.5 km in a 4-year period, with an average of 19.4 ha of woodlands degraded daily. By the end of 2019, charcoal production disturbed most mopane stands in the study area and woodland fragmentation increased in 70.4 % of the mopane woodlands. We estimated that charcoal production was responsible for 2,568,761 Mg (SD = 42,130) of aboveground biomass extracted from the forest and 1,284,381 Mg (SD = 21,075) of carbon loss. The magnitude of these figures underlines the relevance of charcoal production as a main cause of forest cover change and remarks the existing uncertainties in the quantification of forest degradation processes. These results illustrate the potential of multitemporal medium resolution imagery to quantify forest degradation in sub-Saharan Africa and improve REDD + Monitoring, Reporting, and Verification systems in compliance with international reporting commitments.

Monitoring forest degradation from charcoal production with historical Landsat imagery. A case study in southern Mozambique

We used historical Landsat imagery to monitor forest degradation from charcoal production in the main supplying region of the Mozambican capital, Maputo, during a ten-year period (2008–2018). We applied a change detection method that exploits temporal NDVI dynamics associated with charcoal production. This forest degradation temporal sequence exposes the magnitude and the spatial and temporal dynamics of charcoal production, which is the main forest degradation driver in sub-Saharan Africa. The annual area under charcoal production has been steadily increasing since 2008 and reached 11 673 ha in 2018. The total forest degraded extent in the study area during the 10-year study period covered 79 630 ha, which represents 68% of the available mopane woodlands in 2008. Only 5% of the available mopane woodlands area remain undisturbed in the study area. Total gross carbon emissions associated charcoal production during this 10-year period were estimated in 1.13 Mt. These results mark forest degradation from charcoal production as the main driver of forest cover change in southern Mozambique. They also denote that, while charcoal production may be relatively localized in space, its implications for forest cover change and carbon emissions in a sub-Saharan African context are relevant at larger geographical scales. This study represents a proof of concept of the feasibility of medium resolution Earth observation data to monitor forest degradation from charcoal production in the context of the growing urban energy demand. It also highlights the potential opportunities to improve REDD+ monitoring, reporting and verification efforts in sub-Saharan Africa as a first step toward designing effective management and policy interventions.

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

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 SOC and TN and other soil properties vary across woodland types and how charcoal production, the main source of woodland disturbance in the study area, changes these factors 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 as well as both distant from and proximate to sites of active charcoal production, we estimate that these 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 woodlands in the region such as Miombo. Our analysis shows that the woodland types do not differ in terms of the amount of SOC and TN stored in soil, and that soil in the 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 soils. 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.