Spatial and Temporal Trends of Burnt Area in Angola: Implications for Natural Vegetation and Protected Area Management

Abstract

Fire is a key driver of natural ecosystems in Africa. However, human activity and climate change have altered fire frequency and severity, with negative consequences for biodiversity conservation. Angola ranks among the countries with the highest fire activity in sub-Saharan Africa. In this study, we investigated the spatial and temporal trends of the annual burnt area in Angola, from 2001 to 2019, and their association with terrestrial ecoregions, land cover, and protected areas. Based on satellite imagery, we analyzed the presence of significant trends in burnt area, applying the contextual Mann–Kendall test and the Theil–Sen slope estimator. Data on burnt areas were obtained from the moderate-resolution imaging spectroradiometer (MODIS) burnt area product and the analyses were processed in TerrSet. Our results showed that ca. 30% of the country’s area burned every year. The highest percentage of annual burnt area was found in northeast and southeast Angola, which showed large clusters of decreasing trends of burnt area. The clusters of increasing trends were found mainly in central Angola, associated with savannas and grasslands of Angolan Miombo woodlands. The protected areas of Cameia, Luengue-Luiana, and Mavinga exhibited large areas of decreasing trends of burnt area. Conversely, 23% of the Bicuar National Park was included in clusters of increasing trends. Distinct patterns of land cover were found in areas of significant trends, where the clusters of increasing trends showed a higher fraction of forest cover (80%) than the clusters of decreasing trends (55%). The documentation of burnt area trends was very important in tropical regions, since it helped define conservation priorities and management strategies, allowing more effective management of forests and fires in countries with few human and financial resources.

Exploring physicochemical and cytogenomic diversity of African cowpea and common bean

“…The conservation status has been accessed over the last few years, but only 60.9% (39 of the 64 native species) were already evaluated according to the IUCN criteria 34 . Among them, six are classified in the threat categories (one critically endangered and five endangered) and one as near threatened, but this number is likely to increase in the near future, because the pressure on natural resources continues to increase in most African countries, driven by economic and population growth as well as climate change 41 , 42 . Currently, the specific threats to African native pulses species are not well known 14 , but some studies focusing on the conservation of native biodiversity of African legumes 41 – 43 identified deforestation, agriculture and urbanization, harvesting for medicinal uses, fires, and invasive species as the main threats.…”

Assessing the conservation of Miombo timber species through an integrated index of anthropogenic and climatic threats

“…The increasing trends of burned area are strongly related to changes in fire regimes. This factor is based on the mapping of the positive trend of the area burned annually in Angola, analyzed between 2001 and 2019 (for more details, see Catarino et al., 2020). On the reference map, the significant areas of increasing trends of burned area (at a 95% confidence level) and a 5‐km buffer were classified as 10.…”

“…Although wildfires are an important ecological factor in Miombo woodlands, substantial changes in natural fire regimes could be extremely destructive for native flora (Mendelsohn, 2019). Fire frequency has been increasing in recent years, and many anthropogenic fires have occurred in the late dry season, when the trees break dormancy and are more susceptible to damage (Catarino et al, 2020).…”

“…Although wildfires are an important ecological factor in Miombo woodlands, substantial changes in natural fire regimes could be extremely destructive for native flora (Mendelsohn, 2019). Fire frequency has been increasing in recent years, and many anthropogenic fires have occurred in the late dry season, when the trees break dormancy and are more susceptible to damage (Catarino et al., 2020). Fires are also used in agriculture, in the traditional slash‐and‐burn technique, which consists of cutting trees and woody plants from an area and then burning biomass to fertilize the soil with the ashes and clean the area for cultivation and grazing (Schneibel et al., 2016; USAID, 2008).…”

Biodiversity of Vegetation and Flora in Tropical Africa

“…Hammond and Pokorný [7] address the process of succession in a tropical moist semi-deciduous forest, analyzing the diversity of tree species in gap regeneration. The important issue of fire effect on natural vegetation and its implications is presented for Angola by Catarino et al [8], who analyzed the spatial and temporal trends of burnt areas and found increasing trends associated with savannas and grasslands in miombo woodlands' biome.…”