Miombo Ecoregion Vision Report - Biodiversity Foundation for Africa

3.1 Ecoregion Boundary
3. BIOLOGICAL FEATURES AND SPECIES
Miombo Ecoregion Report, page 18
The revised Miombo Ecoregion, also termed the Southern Caesalpinoid woodlands, is an
amalgamation of a number of the smaller ecoregions shown on the WWF-US Conservation
Science Programme map "Terrestrial Ecoregions of Africa" (WWF 1999). It is a broad,
heterogeneous region that covers a large part of south-central Africa, but with many internal
similarities and links. In many respects the revised Miombo Ecoregion can be considered a
"super ecoregion" or biome.
This super-ecoregion is a broader unit than true miombo woodland (defined as woodland
dominated by trees of the genera Brachystegia, Julbernardia and Isoberlinia with a welldeveloped
grass layer), and is defined by the dominance (or high frequency) of trees belonging to
the legume sub-family Caesalpinioideae, such as Brachystegia, Julbernardia, Isoberlinia,
Baikiaea, Cryptosepalum, Colophospermum and Burkea. Its distribution and subdivisions are
shown in Figure 4.
White's original vegetation map (White 1983) was used as a basis for the revision, modified
using a number of national and regional studies 1 . The final map closely follows the boundaries of
the White's Zambezian Regional Centre of Endemism, except for the transition to the Guinea-
Congolia and Zanzibar-Inhambane phytochoria. It also broadly corresponds to the broad-leaved
dystrophic savanna woodlands of southern Africa (Huntley 1982).
The revised Miombo Ecoregion extends from the upper edge of the Angolan escarpment in the
west to the beginnings of the coastal woodlands and forests of Mozambique and Tanzania in the
east (Southern Zanzibar–Inhambane coastal forest mosaic of Burgess et al. 2004), although it
does not include those types. To the west and southwest it is bounded by Kalahari Acacia
woodlands in Namibia and Botswana (Kalahari Acacia–Baikiaea Woodlands of WWF, in part),
and to the south by Highveld grassland and mixed Acacia woodland in South Africa (Highveld
Grasslands of WWF). To the north it grades into Guinea-Congolian moist evergreen forest of the
Congo Basin (Southern Congolian Forest–Savanna Mosaic of WWF), while in the north-east it is
bounded by dry Acacia-Commiphora bushland in Tanzania (Southern Acacia–Commiphora
Bushlands and Thickets of WWF). Nomenclature of the revised units is quite different from that
of the original WWF map, and in many cases the units are substantially different. A comparison
with the WWF-US Ecoregion map is given in Table 1. The total area of the Miombo ecoregion
(excluding water bodies and mountains) is 3,649,568 km 2 .
3.1.1 Inclusions and Exclusions
Although within the geographical extent of the southern Caesalpinoid woodlands, Afromontane
forests and grassland (units 76, 77, 78, 80 (part) of WWF) are excluded from the biological and
other descriptions of the ecoregion. Their ecology and species composition are very different.
Also excluded are large water bodies such as lakes Kariba, Malawi and Tanganyika have been
excluded.
1 National and regional studies used were: Acocks 1975, Barbosa 1970, Bekker & de Wit 1991, Giess 1971, C. Hines
(pers. comm. 2002), Low & Rebelo 1998, Mendelsohn & Roberts 1997, Mendelsohn et al. 2000, Pedro & Barbosa
1955, Timberlake et al. 1993, Timberlake et al. 1994, Wild & Barbosa 1967.