Bridging the Gap: linking timber trade with infrastructural ...

Annex 3
Miombo woodlands of Tanzania
Miombo woodlands span ten countries from the Congo Basin and eastern African savannas west to
Angola, covering a total area of approximately 3.6 million km 2 (Figure 54). They can be defined by the
dominance or high frequency of trees belonging to the legume sub-family Caesalpinioideae, such as
Brachystegia, Julbernardia, Isoberlinia, Baikiaea, Cryptosepalum, Burkea and Colophospermum
(Kojwang, 2001). Mature, relatively undisturbed stands typically comprise a 10-20 m high, single
storey, partly closed canopy of mostly pinnate-leafed
trees; a discontinued under-storey of broad-leafed
shrubs; and an often sparse but continuous
herbaceous layer of forbs, small sedges and C4
grasses (Chidumayo, 1997; Kojwang, 2001). The
majority of miombo woodlands are briefly
deciduous, many of the dominant tree species only
losing their leaves for a short period of the late dry
season. In drier areas, miombo woodlands may be
completely deciduous while in moister areas they
may be virtually evergreen. There are six key
biophysical determinants that pattern miombo
woodlands: long-term geological stability; long dry
season climate lasting over five months; flat
topography and relatively poor drainage; old,
nutrient-poor soils; low levels of large mammal
herbivory with episodic high levels of insect and
small mammal herbivory; and frequent fires
(Kojwang, 2001).
Figure 54
Extent of miombo woodland in southern Africa
and Tanzania
Source: Kojwang, (2001).
In Tanzania, Brachystegia – Julbernardia savanna
woodland covers almost two-thirds of the forested
land (Mgoo et al., 2000). The flora in the miombo
woodlands of Tanzania is estimated at around 8500
species (Anon., 2000a; Anon., 1999i). Gardiner et
al. (1990) documented 106 tree and shrub miombo
species in Ihowanza, Iringa Region, while Malimbwi
et al. (1998) recorded 91 species in Morogoro
District. Wildlife protected areas constitute 47% (96
000 km 2 ) of this zone in Tanzania (Mgoo et al.,
2000). According to Kojwang (2001), four major
vegetation types occur within miombo in Tanzania,
namely dry miombo, wet miombo, Itigi thicket and
wetland/grassland (Figure 54).
Source: Kojwang (2001).
Dry miombo is the dominant woodland type in Tanzania found in most regions. It is floristically poorer
than wet miombo with Brachystegia speciformis, B. boehmii and Julbernardia globiflora dominating.
The canopy is generally less than 15 m in height and trees are deciduous for a month or more during the
dry season. Species of Acacia are found on clay soils in drainage lines. Annual rainfall is less than 1000
112