Miombo Ecoregion Vision Report - Biodiversity Foundation for Africa

Miombo Ecoregion Report, page 6
processes, and (e) conservation of species of special concern. It differs from other approaches in
that it demands a visionary and strategic view in planning to conservation, it operates over large
temporal and bio-geographical scales, and it requires an understanding of social and biological
processes and dynamics operating at these scales. It is usually viewed in the long-term context of
50 years. The broad spatial and temporal scale adopted requires an integrated and multidisciplinary
approach where biological units are the basis for planning and activities. As an
ecoregion unit may cross political boundaries, thinking must extend beyond national boundaries
or programmes, even though requisite conservation actions happen nationally. The challenge is
therefore to operate over these large spatial scales through coordinated and concerted actions
across political boundaries. Although with many attendant difficulties, the often cross-boundary
nature of the approach is vital to achieving long-term ecosystem conservation goals.
1.2 The Miombo Ecoregion
The Miombo Ecoregion, covering over 3.6 million square kilometres across 11 countries of
southern Africa (Figure 1), comprises dry and moist woodlands that support some of the most
important thriving large mammal populations left in Africa. Black rhinoceros, African elephant,
African hunting dog, Cheetah and the Slender-nosed crocodile are some of the threatened
species, along with many less-known species of plant, birds, reptiles, fish and insects. More than
half of the estimated 8,500 plant species in this ecoregion are found nowhere else on Earth. There
is also a distinctive bird, reptile and amphibian fauna.
One of the region's main characteristics is the presence of large expanses of rolling savanna
woodland on a gently undulating plain, interspersed with grassy drainage lines (dambos) in a
regular catenary sequence. The pattern is distinct and repetitive. It is the juxtaposition of different
vegetation types – nutrient poor and nutrient-rich woodland, areas of short nutritive grasses
interspersed with taller rank grass, wetlands in an otherwise dry environment – that allows many
of the large herbivores to survive. The herbivores move through the landscape seasonally,
making the best use of forage resources in what is generally a nutrient-deficient and low
carrying-capacity environment. In many respects, conservation of these woodlands needs to
focus on broad landscape-level processes and hydrology rather than on specific habitats or
species.
The ecoregion is typified by a dominance of deciduous woodland composed of broad-leaved
trees of the legume subfamily Caesalpinioideae. Owing to the deciduous nature of the woodland
there is a well-developed grass layer which, in turn, gives rise to frequent and wide-spreading
fires. Caesalpinoid woodlands are confined to the gently undulating, unrejuvenated Central
African plateau at an altitude of 800–1200 m, although they come down to the coastal plain in
Mozambique and Tanzania. The ecoregion is incised by the large river valleys of the Zambezi,
Luangwa and Limpopo, and by the Rift Valley lakes of Tanganyika and Malawi. A number of
major drainage basins such as the Zambezi, Limpopo, Save, Cuando, Kavango, Rufiji, Rovuma
and Luapula (part of the Upper Congo) are incorporated.
Although the ecoregion is commonly termed the Miombo Ecoregion, this is confusing as the
Caesalpinoid woodlands which it comprises extend significantly beyond true miombo woodland.
A unimodal rainfall pattern with distinct and prolonged dry seasons, coupled with the generally
leached and impoverished soils, are major features. It is the combination of environmental
factors– rainfall, length of dry period, soil nutrient status and fire – which is the probable main
determinant of woodland limits and separates this from adjacent ecoregions.