Afromontane

The Afromontane regions are subregions of the Afrotropical realm, one of the Earth's eight biogeographic realms, covering the plant and animal species found in the mountains of Africa and the southern Arabian Peninsula. The Afromontane regions of Africa are discontinuous, separated from each other by lower-lying areas, and are sometimes referred to as the Afromontane archipelago, as their distribution is analogous to a series of sky islands.

Afromontane Zones. I. West African and Cameroon highlands, II. Ethiopian and Arabian highlands, III. Western (Albertine) Rift, IV. Eastern Rift. V. Southern Rift, VI. Eastern Highlands, VII. Drakensberg

Geography

Afromontane communities occur above 1,500–2,000 metres (4,900–6,600 ft) elevation near the equator, and as low as 300 metres (980 ft) elevation in the Knysna-Amatole montane forests of South Africa. Afromontane forests are generally cooler and more humid than the surrounding lowlands.

The Afromontane archipelago mostly follows the East African Rift from the Red Sea to Zimbabwe, with the largest areas in the Ethiopian Highlands, the Albertine Rift Mountains of Uganda, Rwanda, Burundi, Democratic Republic of the Congo, and Tanzania, and the Eastern Arc highlands of Kenya and Tanzania. Other Afromontane regions include the Drakensberg range of southern Africa, the Cameroon Highlands, and the Cameroon Line volcanoes, including Mount Cameroon, Bioko, and São Tomé.

Flora

Although some Afromontane enclaves are widely separated, they share a similar mix of plant species which are often distinct from the surrounding lowland regions.[1] Podocarps, of genera Podocarpus and Afrocarpus, are a characteristic tree, along with Prunus africana, Hagenia abyssinica, Juniperus procera, and Olea spp.. In the higher mountains, the Afromontane forest or woodland zone transitions to a higher Afroalpine zone of grasslands, shrublands, or moorlands.[2][3]

The plant families Curtisiaceae and Oliniaceae are Afromontane endemics and family Barbeyaceae is a near-endemic. The tree genera Afrocrania, Balthasaria, Curtisia, Ficalhoa, Hagenia, Kiggelaria, Kuloa, Leucosidea, Platypterocarpus, Trichocladus, Widdringtonia, and Xymalos are Afromontane endemics or near-endemics, as are the plant genera Ardisiandra, Cincinnobotrys, and Stapfiella.[1]

Plant communities

Afromontane areas have a wide range of plant communities, including intermediate types. These include:

Distribution
Eastern Afromontane biodiversity hotspot

In South Africa, Afromontane forests cover only 0.5% of the country's land area. The Afromontane forests occur along the mountainous arc of the Drakensberg Range, from Limpopo Province in the northeast to the Western Cape Province in the southwest. The Afromontane forests generally occur in well-watered areas, including ravines and south-facing slopes. The Afromontane forests are intolerant of fire, and the frequent fires of the surrounding fynbos, savanna, and grassland limit the expansion of the forests. Despite their small area, the Afromontane forests of South Africa produce valuable timber, particularly the real yellowwood (Podocarpus latifolius), Outeniqua yellowwood (Afrocarpus falcatus), and stinkwood (Ocotea bullata).

Afromontane ecoregions
Tropical and subtropical moist broadleaf forests
Montane grasslands, shrublands, and woodlands
Deserts and xeric shrublands
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References
  1. White, F.; Unesco; Association pour l'étude taxonomique de la flore d'Afrique tropicale; United Nations Sudano-Sahelian Office (1983). Vegetation of Africa : a descriptive memoir to accompany the Unesco/AETFAT/UNSO vegetation map of Africa. Paris: Unesco. ISBN 92-3-101955-4. OCLC 10387142.
  2. Brochmann, Christian; Gizaw, Abel; Chala, Desalegn; Kandziora, Martha; Eilu, Gerald; Popp, Magnus; Pirie, Michael D.; Gehrke, Berit (2021-07-19). "History and evolution of the afroalpine flora: in the footsteps of Olov Hedberg". Alpine Botany. Springer Science and Business Media LLC. 132 (1): 65–87. doi:10.1007/s00035-021-00256-9. ISSN 1664-2201. S2CID 237643374.
  3. Kandziora, Martha; Gehrke, Berit; Popp, Magnus; Gizaw, Abel; Brochmann, Christian; Pirie, Michael D. (2022-05-26). "The enigmatic tropical alpine flora on the African sky islands is young, disturbed, and unsaturated". Proceedings of the National Academy of Sciences. 119 (22): e2112737119. Bibcode:2022PNAS..11912737K. doi:10.1073/pnas.2112737119. ISSN 0027-8424. PMC 9295768. PMID 35617436.
  • Galley, C. & Linder, H. P. (2006) Geographical affinities of the Cape flora, South Africa. Journal of Biogeography 33 (2), 236–250.
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