Ecoregions of Angola

July 5, 2012, 7:33 am
Content Cover Image

Huambo province, Angola. Photograph by Brian Huntley

There are thirteen ecoregions in Angola:

  1. Kaokoveld desert
  2. Namibian savanna woodlands
  3. Angolan Mopane woodlands
  4. Zambezian Baikiaea woodlands
  5. Western Zambezian grasslands
  6. Zambezian Cryptosepalum dry forests
  7. Angolan Miombo woodlands
  8. Angolan montane forest-grassland mosaic
  9. Angolan scarp savanna and woodlands
  10. Western Congolian forest-savanna mosaic
  11. Southern Congolian forest savanna mosaic
  12. Central Zambezian Miombo woodlands
  13. Central African mangroves

 

Kaokoveld desert

The Kaokoveld Desert stretches along the west coast of southern Africa between about 13 and 21S latitude. Encompassing the northern Namib Desert, the ecoregion extends from the Uniab River in Namibia northwards into the coastal zone of southern Angola, including the Mossamedes Desert. For most of its length, it is about 100 kilometers (km) wide and extends from the Atlantic Coastline to the foot of the great escarpment, which delimits the interior highlands of southern Africa.

The Kaokoveld Desert represents the northern area of the vast Namib Desert. It is a harsh, arid landscape of rugged mountains, gravel plains and shifting sand dunes. Surface water is scarce, with only one perennial river flowing through the region, the Kunene River. However, the dry riverbeds transecting the area are the lifelines of the desert. They are well vegetated and are home to large mammals such as elephants, black rhinos and giraffes. The rest of the landscape is poorly vegetated and extremely dry. Coastal fogs allow a range of interesting, desert-adapted animal species to survive in this low-rainfall environment. The relict gymnosperm Welwitschia mirabilis, which represents the sole surviving member of its family, is found throughout the ecoregion. The Kaokoveld Desert is well protected in the Skeleton Coast National Park, but outside this park the habitat is under threat. In Namibia, the area is threatened by poaching, and by unruly off-road enthusiasts. On the Angolan side, threats come from the collapse of infrastructure and of governance during a thirty year civil war which ended in 2002.

Namibian savanna woodlands

The Namibian Savanna Woodland ecoregion covers the Great Escarpment that delimits the interior of Southern Africa from the Kaokoveld and Namib Deserts. This broken and deeply dissected escarpment is an area of high endemism for plants, invertebrates, amphibians, reptiles, mammals and birds. The northern area of the escarpment, the Kaoko escarpment, is an endemism "hotspot" (an area of extremely high species richness and endemism). This northern area is poorly protected and is under threat from poaching, off-road driving, and to a lesser extent from farming, and resultant habitat fragmentation. The formal conservation status of the southern portion of the ecoregion is poor. Other forms of protection, such as conservancies, private nature reserves and game farms do, however, promote conservation of the area. If these areas can be effectively managed through collaboration with local communities, they may solve the conservation crisis in the area.

The Kunene River that runs along the Angola-Namibia border is the only perennial river within the ecoregion.

Angolan Mopane woodlands

The Angolan Mopane Woodlands are located in northern Namibia and  southern Angola, completely surrounding the Etosha Pan, of Namibia which is considered a separate ecoregion. Mopane trees (Colophospermum mopane) dominate the vegetation, and are an essential resource for both the people and wildlife of the region. Elephants (Loxodonta africana) utilize almost every part of the mopane tree, and the region supports other large herbivores, including the critically endangered black rhino (Diceros bicornis). Species richness in this ecoregion is high, especially in comparison with the arid deserts to the west. Conservation potential is high in Namibia, due to the well-established Etosha National Park, and increasing community involvement and ownership of natural resources. Conservation in Angola has been severely compromised by the lengthy civil war, and many large mammal populations are near local extinction.

The Kunene River is the only perennial river flowing through this ecoregion. Its catchment lies to the north of the ecoregion in the Angolan highlands. The Kunene flows south through the ecoregion, and then it heads southwest into the Namibian Savanna Woodland ecoregion where it forms the border between Angola and Namibia.

Two national parks occur on the Angolan side of the ecoregion. These are Bikuar National Park (7900 km2) and Mupa National Park (6600 km2). While these two parks cover a representative area of the Angolan Mopane Woodlands, they do not offer adequate protection, as a result of the 30-year civil war in the country which ended in 2002.

Zambezian Baikiaea woodlands

Deep Kalahari sands occur in a wide belt along the Angolan-Namibian border across to Zimbabwe, supporting dry deciduous forest dominated by Baikiaea plurijuga. The hot, semi-arid climate and nutrient-poor soils mean that this region is not suitable for farming, and thus it has retained some of its natural vegetation. Over 160 mammal species are found here, including ungulates and large predators. However, settlements occur along rivers, and the valuable Baikiaea plurijuga is sought after for the timber trade.

This ecoregion is a mosaic of dry deciduous Baikiaea plurijuga-dominated forest, thicket, and secondary grassland. The area falls within the Zambezian center of endemism and coincides largely with White’s Zambezian dry deciduous forest and scrub forest. This ecoregion forms a belt on deep Kalahari sands along the Angola-Namibia border, extending in a straight line to southwestern Zimbabwe. A portion of this ecoregion extends northwards, along the Zambia-Angola boundary. It is defined and shaped by a number of factors. The limits of the Kalahari sand delineate the east and west extent of this belt, while the southern boundary is limited by frost, and to the north, as rainfall increases the vegetation turns into evergreen Cryptosepalum forests and miombo woodland. Around the Barotse floodplain, seasonal waterlogging or flooding suppresses tree growth, and Baikiaea woodlands give way to grasslands. While the distribution of the forest, woodland, savanna, and grassland elements is partly determined by edaphic and climatic factors, disturbance factors such as fire, logging, and agriculture play an increasing role in the spread of secondary savanna and grassland.

On the whole, this ecoregion is fairly sparsely settled with fewer than 5 people per km2 in most areas. In the least populated areas, population densities are probably less than one person per km2. As a result of the scattered human population and the arid nature of the environment, much of the habitat has not been modified or fragmented. However, especially in Zambia, Angola, and Zimbabwe, timber logging together with frequent wildfires has significantly reduced the area of mature Baikiaea woodland and forest.

There are three protected areas in Angola, Bikuar and Mupa National Parks, and Luiana Partial Reserve.

Western Zambezian grasslands

This ecoregion is located in southwestern Zambia, in two main portions within White’s Zambesian Center of Endemism. It extends marginally into Angola, where the grasslands are soon replaced by the Angolan Miombo Woodland ecoregion. The northern and main portion of the ecoregion consists of edaphic grasslands surrounding the patchy Zambezian Cryptosepalum Dry Forest ecoregion.

Many ungulates are found here, including the largest herd of blue wildebeest (Connochaetes taurinus) in Zambia, which undertake a spectacular migration into Angola each year. The grasslands have been inhabited by people for centuries, but are adapted to some human disturbances such as fires, and have a long history of traditional sustainable management.

Zambezian Cryptosepalum dry forests

This small but distinctive ecoregion consists almost entirely of dense evergreen forest dominated by Cryptosepalum exfoliatum pseudotaxus, known locally as "mavunda." It falls into the Zambezian regional center of endemism and is mapped as ‘Zambezian dry evergreen forest.’ The two main blocks of Cryptosepalum forest are found to the north and south of the Kabompo River. Together they constitute the largest area of tropical evergreen forest in Africa outside the equatorial zone.

The ecoregion is found at 1,100 to 1,200 meters (m) elevation in the higher rainfall areas of the Kalahari sands of northern Barotseland in western Zambia, and marginally extends into Angola.

Angolan Miombo woodlands

Covering all of central Angola and extending into the Democratic Republic of Congo, the extensive Angolan miombo woodlands are part of an even larger miombo ecosystem that covers much of eastern and southern Africa. The miombo is characterized by several unique ecological factors, including its propensity to burn, the importance of termites, and the unusual browsing conditions found here. While only poor-quality browsing is available, this ecoregion hosts a rich assortment of large mammals, some bulk feeders like the African elephant (Loxodonta africana), some specialized feeders such as the sable antelope (Hippotragus niger), and some, such as the tsessebe (Damaliscus lunatus), that utilize the wetlands scattered throughout this ecoregion. However, large mammal populations and all conservation activities have been severely affected by the decades-long civil war in Angola since 1974.

This ecoregion comprises moist, deciduous broadleaf savannas and woodlands interspersed with areas of edaphic and secondary grassland. It forms the westernmost part of the large miombo woodland belt that is the dominant type of savanna woodland in the Zambezian center of endemism. To the north and northeast lie the Southern and Western Congolian Forest-Savanna Mosaic vegetation, while the drier Zambezian Baikiaea Woodland is found on Kalahari sands to the south. The high peaks of the western highlands and the escarpment form the western boundary of the ecoregion where the miombo gives way to the Angolan Scarp Savanna and Woodlands and, at the highest elevations, to the Angolan Montane Forest-Grassland Mosaic. To the east lie the floristically distinct Central Zambezian Miombo Woodlands and the Zambezian Cryptosepalum Dry Forests and the Western Zambezian Grasslands.

Overall species richness of the ecoregion’s flora is high, though the diversity of canopy tree species is relatively low. Miombo is notable among dry tropical woodlands for the dominance of tree species with ectomycorrhizal rather than vesicular-arbuscular mycorrhizal associations. These may enable them to exploit porous, infertile soils more efficiently than groups lacking ectomycorrhizae. Many of the fungal species involved in these associations produce mushrooms, some of which are edible. This has resulted in a culture of mushroom-gathering among indigenous people that is widespread in miombo, but largely absent in other tropical African woodlands.

Faunal richness is moderate, with birds being better represented than other vertebrate taxa. The ecoregion is part of the large miombo woodland belt, the most extensive tropical seasonal woodland and dry forest formation in Africa, covering an estimated 2.7 million km2. Many of the plant and animal species found in the ecoregion are widespread throughout the savanna and woodland areas in southern Africa. While there are many species specialized and endemic to miombo vegetation, relatively few are confined to this ecoregion. Because little biological research has been carried out in Angola over the last 25 years due to the ongoing civil war, species richness estimates are likely to be an under-representation. Some of the species reported as endemic are poorly studied and collected, and their ranges may, in fact, be larger than is currently known.

Angolan montane forest-grassland mosaic

This ecoregion comprises a number of small montane forest patches surrounded by grasslands and Protea savanna in the west-central highlands of Angola. The forest patches are restricted to the deep ravines or remote valleys of the highest mountains in the Huambo and Cuanza Sul provinces and an area of Afromontane forest mosaic further south, on the Serra da Chela in Huíla province. The ecoregion represents a small fragment of the Afromontane archipelago-like center of endemism, which consists of widely scattered "islands" of forest on mountain systems in southern, eastern, and western Africa. The characteristic elements of the ecoregion’s fauna and flora are more closely related to other such [Afromontane areas than to the surrounding Angolan biomes.

The ecoregion lies on the Marginal Mountain Chain of Angola, which is restricted to a narrow band running along the inland margin of the escarpment from 11° to 16° S. Residual land surfaces that possibly date back to the Gondwanan age form the highest points here, reaching 2,620 meters (m) on Mt. Môco, 2,582 m on Mt. Mepo, and 2,554 m on Mt. Lubangue.

The forests of this ecoregion are highly fragmented as a result of fires, agriculture, and woodcutting. The remaining forest patches seldom exceed 20 ha in size, and their total area is probably less than 200 ha. The most extensive forest areas, at Mt. Namba, were exploited for timber during the colonial period and are devoid of pristine patches. Relatively undisturbed patches remain at Mt. Môco between 1,800 and 2,400 m elevation. However, due to the lack of data, it is not known how extensive the forest patches once were, and at what rate their extent and quality have changed since the 1970’s. No protected areas currently exist in this ecoregion. Unless drastic conservation efforts are implemented, it is possible that little or nothing will remain of the forest patches and their fauna.

Angolan scarp savanna and woodlands

This ecoregion comprises a long narrow strip of land running from about 6° to 14° S latitude between the Atlantic Ocean, the Southwest Arid biome of Angola and the top of the scarp face of the Central African Plateau. It is a complex area where several major African ecological zones meet, and where topographical features have resulted in a high diversity of vegetation types and significant levels of endemism. Biologically, the most important portion of the ecoregion is the west-facing scarp that supports rain forest at higher altitudes. This forest holds a significant number of endemic birds, and some other endemic animals and plants. The long period of civil instability in Angola means that these forests and other parts of the ecoregion have never been adequately surveyed biologically, and hence more endemics can be expected with further study.

Due to its low agricultural potential, the dry coastal belt and lower escarpment are relatively sparsely settled, and large areas remain unfragmented. For instance, large stretches of completely undisturbed habitat have been reported in Kisama National Park. Around the larger urban centers, particularly Luanda, human settlement and activities such as woodcutting and livestock grazing have had considerable, though mostly localized, impacts on the vegetation and soils.

Two areas in the ecoregion are protected, with three more areas proposed for protection but not yet established. The large Kisama National Park is bordered by the Atlantic Coast and the banks of the Cuanza and Longa Rivers and is listed by many to be among critical sites for biodiversity conservation. Marine, estuarine, floodplain, grassland and thicket habitats are represented here. Ilheu dos Passaros Integral Nature Reserve is a small offshore island with mangrove communities and mud flats which are of great botanical interest and provide key breeding habitats for water birds.

The proposed Gabela and Chingoroi Strict Nature Reserves, both representing patches of escarpment forest, are needed to protect the area’s rare endemic bird species, because their small forest habitats are declining due to agricultural activities. Without these two protected areas, the escarpment forest vegetation and its fauna are unprotected despite their vulnerability and great biological interest. The Pungo Andongo Natural Monument comprises a series of large rocky outcrops between Gabela and the coast, which should be protected for their biological and aesthetic value.

Western Congolian forest-savanna mosaic

This ecoregion consists of 159,700 square miles of tropical and subtropical grasslands, savannas, and shrublands covering much of the southern part of the the Republic of Congo and the western part of the Democratic Republic of the Congo, extending north into Gabon and south into Angola.

Southern Congolian forest savanna mosaic

Covering a broad area of southern Democratic Republic of Congo, the Southern Congolian Forest-Savanna Mosaic is a blend of forest, woodland, shrubland and grassland habitats. While the forests here boast only a few endemic species, they have a rich fauna, including a number of different antelope species and high numbers of African elephants. This rich blend of habitats provides key insights into the biogeography of Central Africa, which has experienced large climatic fluctuations over the last 10 million years. While there is only one protected area in this ecoregion, the human population is low. However, the civil war in the Democratic Republic of Congo has had unknown effects on this ecoregion and, until stability returns, no significant conservation work is likely to be accomplished.

Central Zambezian Miombo woodlands

The Central Zambezian Miombo Woodland is one of the largest ecoregions in Africa, ranging from Angola up to the shores of Lake Victoria in Tanzania. All the typical miombo flora are represented here, but this region has a higher degree of floral richness, with far more evergreen trees than elsewhere in the miombo biome. The harsh dry season, long droughts, and poor soils are ameliorated by the numerous wetlands spread throughout the ecoregion, covering up to 30 percent of the region’s total area. As a result, a diverse mix of animals is found here, from sitatunga (swamp-dwelling antelopes), to chimpanzees, in the world-famous Gombe Stream Reserve. The bird life is also exceptionally rich, as is the fauna of some amphibian groups. The ecoregion contains areas of near-wilderness with exceptionally low human populations and extensive protected areas. Other parts of the ecoregion, typically close to lakes and mountains, have higher population densities and the miombo is much more degraded. Bushmeat hunting, dryland agriculture, deforestation especially for charcoal production near larger towns, and mining are increasing threat in this ecoregion.

Central African mangroves

The Central African mangrove ecoregion is located in western Africa, and encompasses mangrove areas along the coastlines of Ghana, Nigeria, Cameroon, Equatorial Guinea, Gabon, Democratic Republic of Congo (DRC), and Angola (to 19°18' S). The structure of the mangrove areas varies considerably, from the lagoon systems found in the western part of this ecoregion to systems modified by complex patterns of sediment deposition at river mouths in the central and southern portions.

These mangroves flank the coastline of western and central Africa, in suitable low energy marine environments. The largest mangrove stand is found in the Niger Delta, which supports the most extensive area of mangrove in Africa. In Angola, large mangrove communities occur at the mouths of the Cuvo, Longa, Cuanza, Dande, and M'Bridge Rivers, though they are not as extensive as the vast mangrove swamps at the mouth of the Zaire River. The dominant trees are Rhizophora racemosa, R. mangle, R. harrisonii and, Avicennia africana, the former two species reaching heights of approximately 30 meters (m).

Context

Ecoregions are areas that:

[1] share a large majority of their species and ecological dynamics;
[2] share similar environmental conditions; and,
[3] interact ecologically in ways that are critical for their long-term persistence.

Scientists at the World Wildlife Fund (WWF), have established a classification system that divides the world in 867 terrestrial ecoregions, 426 freshwater ecoregions and 229 marine ecoregions that reflect the distribution of a broad range of fauna and flora across the entire planet.

Glossary

Citation

Fund, W. (2012). Ecoregions of Angola. Retrieved from http://www.eoearth.org/view/article/177200