Science of The Total Environment

2022

DOI: 10.1016/j.scitotenv.2021.152315

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Angolan highlands peatlands: Extent, age and growth dynamics

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Jennifer M. Fitchett

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Stephan Woodborne

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Cited by 13 publications

(27 citation statements)

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“…The study site is in the southeast of Angola, predominantly within Moxico province, spanning a latitudinal range of 11°54′–13°54′S and longitudinal range of 18°05′–20°34′E, and covering approximately 61,590 km 2 . The LULC classification map produced by Lourenco et al, ( 2022a , b ) includes six land cover classes: peatland, miombo woodland, valley grassland, upland grassland, water, and cleared/ cultivated land (Fig. 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…The LULC of the study area (Fig. 1 ) was classified using 20 m resolution imagery from the Copernicus Sentinel-2 satellite and 30 m resolution imagery from the USGS Landsat 8 satellite (Lourenco et al, 2022a ). The map is based on imagery acquired from each satellite from March 2017 to February 2021 (Lourenco et al, 2022a ).…”

Section: Methodsmentioning

confidence: 99%

“…1 ) was classified using 20 m resolution imagery from the Copernicus Sentinel-2 satellite and 30 m resolution imagery from the USGS Landsat 8 satellite (Lourenco et al, 2022a ). The map is based on imagery acquired from each satellite from March 2017 to February 2021 (Lourenco et al, 2022a ). Ground-based data obtained by the National Geographic Okavango Wilderness Project (NGOWP) was used as training data for this classification over the same period (Lourenco et al, 2022a ), and later validation following a field campaign in June 2022.…”

Section: Methodsmentioning

confidence: 99%

“…The Angolan Highlands are hydrologically and ecologically important, supporting miombo woodlands (Mendelsohn, 2019 ), grasslands, subsistence agricultural land, and peatland deposits (Lourenco et al, 2022a ). Peatlands are terrestrial ecosystems that facilitate the growth of peat, an organic-rich soil that consists of partially decomposed organic matter derived from plant material (Dargie et al, 2017 ; IPS, 2021 ; Lourenco et al, 2022b ).…”

Section: Introductionmentioning

confidence: 99%

“…Due to the Angolan Civil war from 1975 to 2002 and widespread minefields, the eastern Angolan Highlands region remains under-studied (Conradie et al, 2016 ; Midgley & Engelbrecht, 2019 ). However, a recent land use/land cover (LULC) classification for the region estimates that the extent of peatlands is at least 1634 km 2 within an area spanning 61,590 km 2 (Lourenco et al, 2022a ).…”

Section: Introductionmentioning

confidence: 99%

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Fire regime of peatlands in the Angolan Highlands

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2022

Environ Monit Assess

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The Angolan Highlands region includes the Angolan miombo woodland ecoregion which supports miombo woodland, grasslands, subsistence agricultural land, and peatland deposits. Extensive fires, slash and burn agriculture, peat fuel extraction, and peatland drainage are among the anthropogenic practices that threaten these peatland deposits. Peat fires cause peatland degradation, release significant amounts of greenhouse gases, deteriorate air quality, and contribute towards climate change and biodiversity loss. This study presents an analysis of the fire regimes over the period 2001 to 2020 in an under-studied area of the Angolan Highlands. Moderate Resolution Imaging Spectroradiometer (MODIS) fire and vegetation data were used in combination with a land use/land cover (LULC) classification map to calculate fire frequency, burn area, and fire regimes. The fire patterns within the study site are comparable to those found in African woodland savannas. Across the study site, 6976 km 2 (11.31%) of the land surface area burned at least nine times from 2001 to 2020, occurring largely within in the river valley environment. Considering the different LULC classes, peatlands were calculated to (a) burn more frequently (average fire frequency from 2001 to 2020 = 9.12), (b) have the smallest proportion (4.11%) of area which remained unburnt over the fire archive, and (c) have the largest average proportion (45.65% or 746 km 2 ) of burnt area per year. Peatland burning occurred predominantly during drier months from May to September. The results of this study highlight the strong influence of LULC on the fire frequency and distribution in the study area, requiring unique fire management strategies. As has been documented for boreal and tropical peatlands across the globe, we stress the importance of peatland conservation and protection; continued unsustainable management practices may lead to the loss of these important peatland deposits. Supplementary Information The online version contains supplementary material available at 10.1007/s10661-022-10704-6.

“…The study site is in the southeast of Angola, predominantly within Moxico province, spanning a latitudinal range of 11°54′–13°54′S and longitudinal range of 18°05′–20°34′E, and covering approximately 61,590 km 2 . The LULC classification map produced by Lourenco et al, ( 2022a , b ) includes six land cover classes: peatland, miombo woodland, valley grassland, upland grassland, water, and cleared/ cultivated land (Fig. 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…The LULC of the study area (Fig. 1 ) was classified using 20 m resolution imagery from the Copernicus Sentinel-2 satellite and 30 m resolution imagery from the USGS Landsat 8 satellite (Lourenco et al, 2022a ). The map is based on imagery acquired from each satellite from March 2017 to February 2021 (Lourenco et al, 2022a ).…”

Section: Methodsmentioning

confidence: 99%

“…1 ) was classified using 20 m resolution imagery from the Copernicus Sentinel-2 satellite and 30 m resolution imagery from the USGS Landsat 8 satellite (Lourenco et al, 2022a ). The map is based on imagery acquired from each satellite from March 2017 to February 2021 (Lourenco et al, 2022a ). Ground-based data obtained by the National Geographic Okavango Wilderness Project (NGOWP) was used as training data for this classification over the same period (Lourenco et al, 2022a ), and later validation following a field campaign in June 2022.…”

Section: Methodsmentioning

confidence: 99%

“…The Angolan Highlands are hydrologically and ecologically important, supporting miombo woodlands (Mendelsohn, 2019 ), grasslands, subsistence agricultural land, and peatland deposits (Lourenco et al, 2022a ). Peatlands are terrestrial ecosystems that facilitate the growth of peat, an organic-rich soil that consists of partially decomposed organic matter derived from plant material (Dargie et al, 2017 ; IPS, 2021 ; Lourenco et al, 2022b ).…”

Section: Introductionmentioning

confidence: 99%

“…Due to the Angolan Civil war from 1975 to 2002 and widespread minefields, the eastern Angolan Highlands region remains under-studied (Conradie et al, 2016 ; Midgley & Engelbrecht, 2019 ). However, a recent land use/land cover (LULC) classification for the region estimates that the extent of peatlands is at least 1634 km 2 within an area spanning 61,590 km 2 (Lourenco et al, 2022a ).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fire regime of peatlands in the Angolan Highlands

¹

,

²

,

³

2022

Environ Monit Assess

Self Cite

View full text Add to dashboard Cite

The Angolan Highlands region includes the Angolan miombo woodland ecoregion which supports miombo woodland, grasslands, subsistence agricultural land, and peatland deposits. Extensive fires, slash and burn agriculture, peat fuel extraction, and peatland drainage are among the anthropogenic practices that threaten these peatland deposits. Peat fires cause peatland degradation, release significant amounts of greenhouse gases, deteriorate air quality, and contribute towards climate change and biodiversity loss. This study presents an analysis of the fire regimes over the period 2001 to 2020 in an under-studied area of the Angolan Highlands. Moderate Resolution Imaging Spectroradiometer (MODIS) fire and vegetation data were used in combination with a land use/land cover (LULC) classification map to calculate fire frequency, burn area, and fire regimes. The fire patterns within the study site are comparable to those found in African woodland savannas. Across the study site, 6976 km 2 (11.31%) of the land surface area burned at least nine times from 2001 to 2020, occurring largely within in the river valley environment. Considering the different LULC classes, peatlands were calculated to (a) burn more frequently (average fire frequency from 2001 to 2020 = 9.12), (b) have the smallest proportion (4.11%) of area which remained unburnt over the fire archive, and (c) have the largest average proportion (45.65% or 746 km 2 ) of burnt area per year. Peatland burning occurred predominantly during drier months from May to September. The results of this study highlight the strong influence of LULC on the fire frequency and distribution in the study area, requiring unique fire management strategies. As has been documented for boreal and tropical peatlands across the globe, we stress the importance of peatland conservation and protection; continued unsustainable management practices may lead to the loss of these important peatland deposits. Supplementary Information The online version contains supplementary material available at 10.1007/s10661-022-10704-6.

Drought history and vegetation response in the Angolan Highlands

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2022

Theor Appl Climatol

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Defining the Angolan Highlands Water Tower, a 40 plus-year precipitation budget of the headwater catchments of the Okavango Delta

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2023

Environ Monit Assess

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Angola is a source of many major rivers in southern Africa and is referred to as the “water tower” of the region. The lack of a defined area delineating the Angolan Highlands water tower (AHWT) limits the conservation of this important freshwater source. This study hydrologically defines the boundary of the AHWT as areas > 1274 m above mean sea level within the Central Bié Plateau of Angola. Using the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) data, this study provides a 41-year precipitation budget of the AHWT and surrounding basins. Between 1981 and 2021, the average annual precipitation over the AHWT was 1112 mm and the gross annual average precipitation volume was approximately 423 km3 over an area of 380,382 km2. The AHWT is the southern source of the Congo Basin, the western source of the Zambezi Basin, and the sole water source of the endorheic Okavango Basin and Okavango Delta, a UNESCO World Heritage Site. On average, approximately 133 km3 (92.36%) of the gross annual precipitation volume for the headwater Cuito and Cubango catchments of the Okavango River is lost before reaching the Okavango Delta. Estimates of the annual flooding of the Okavango Delta during a 35-year period (1985–2019) were correlated to precipitation in the headwater catchments. Correlation coefficients are stronger for the entire rainfall season (0.76) and early rainfall season (0.62) for the combined Cuito–Cubango catchment in comparison to late rainfall season (0.50), which suggests that the antecedent conditions (first and second flood pulse) during the early rainfall season allows for greater Okavango Delta flood inundation. The correlation coefficients between the Cubango (0.72) and Cuito (0.78) Rivers and annual flood inundation are not significantly different (P > 0.05); however, these rivers have fundamental hydrological differences that influence the functioning of the Okavango Delta. The Cubango River, described as a flushing system, has much steeper gradient, more compact and shallow soils and flows faster with significant rapids, whereas the peatland rich, absorbent, seepage-driven baseflow of the Cuito River sustains the Okavango Delta during the dry season. The dynamics of seasonal precipitation, hydrology and climate change in the AHWT have important repercussions on water budgets, food security and biodiversity throughout southern Africa, requiring continued collaboration between countries to ensure that future development is sustainable.

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