Miombo Ecoregion Vision Report - Biodiversity Foundation for Africa

Miombo Ecoregion Report, page 22
As dry miombo woodland is found on escarpments as well as on the plateau and coastal plain, the
geomorphology and soils are more varied than with wet miombo. There is also a significant
inclusion of mopane, Acacia and Combretum woodlands in places. There are no significant areas
of floodplain grassland or wetlands, but seasonally waterlogged drainage-line grasslands
(dambos) are common on the central plateau.
Burkea–Terminalia woodland: This rather impoverished woodland type is found at the southern
margins of the ecoregion. Although similar in structure and broad ecology to dry miombo
woodland, it does not contain any of its defining species. Instead there is a high frequency of
Burkea africana, Terminalia sericea, Combretum, Pterocarpus, Pseudolachnostylis
maprouneifolia and other broad-leaved trees typical of dystrophic woodland, along with species
of Acacia, Albizia and Peltophorum africanum. There are many rocky outcrops which support
mesic species.
It is principally found on the southern part of the central plateau at over 1000 m altitude. Annual
rainfall is around 600 mm, with high variability. The type has been much modified by human
activity.
Baikiaea woodland: Baikiaea woodland varies in structure from almost dry forest or thicket to a
moderately-dense woodland. It is characterised by a dominance of the deep-rooted tree Baikiaea
plurijuga, and is confined to deeper Kalahari sands. Canopy height varies from 8 to 20 m,
depending on rainfall. Other typical species include Burkea africana, Combretum collinum and
Guibourtia coleosperma. The type is deciduous, often for some months. Annual rainfall varies
from 500 to 800 mm, but the deep sands absorb and retain moisture well so deep-rooted trees
retain their leaves for an extended period.
Mopane woodland: Mopane woodland is characterised by the dominance of Colophospermum
mopane with a canopy from 6 to 18 m high, depending on rainfall and soil depth. Trees are
deciduous for some months of the year. The grass layer is generally poorly developed. These
woodlands are species-poor; associated species include Acacia and those from the Capparidaceae
family.
It is associated with nutrient-rich clay soils of the wide, flat valleys such as the Limpopo, Save,
Zambezi, Luangwa and Cunene. Altitude ranges from 300 to 900 m. Mopane woodland is a
eutrophic (nutrient-rich) type with a different ecology to true miombo. Annual rainfall is around
400 to 700 mm with high variability, but soil infiltration rates are low.
Acacia–Combretum woodland: This type comprises open woodland to wooded grassland
dominated by species of Acacia and Combretum, often with trees from the legume subfamily
Papilionoideae. There are two variants. One is found up on the central plateau of eastern Zambia
in dry miombo on areas of nutrient-rich soil, sometimes locally called "munga". It consists of
open woodland to wooded grassland with a well-developed grass layer, and is frequently burnt.
Along with Combretum and Terminalia, a number of mesic Acacia and Albizia species, and
species from the families Papilionoideae and Bignoniaceae occur. The other variant is found
where the central plateau falls away to the Mozambique coastal plain and Zambezi valley. The
climate is generally warmer, and fire is less frequent. Acacia nigrescens and Combretum species
are very common, and are associated with Lonchocarpus capassa, Xeroderris stuhlmannii,
Sterculia africana, Adansonia digitata and Cordyla africana. Mopane is often present, but is not
dominant or abundant. The grass layer is variously well or poorly-developed, depending on soil
depth and rainfall.