The range of low hills running south-west from Dar es Salaam to the border of the Selous Game Reserve attracts higher rainfall than the coastal plain and this has resulted in the development of evergreen forest with a poor ground flora on the mainly dry sandy soils. Three Forest Reserves comprise this site: Pugu Hills Forest Reserve (2,180 ha), of which less than 400 ha remains in reasonable condition; Kazimzumbwi Forest Reserve (4,887 ha), of which perhaps only 900 ha can be considered forest; and Ruvu South Forest Reserve (35,000 ha), of which only 10,000 ha can be considered forest. The north-eastern corner of Ruvu South comes within 1 km of the north-western end of Pugu and is only 2 km from the western edge of Kazimzumbwi. Forest composition varies considerably between the three reserves, largely due to the past removal of valued timber, but also reflecting differing soil and groundwater conditions. The only tall (35 m) emergents in Pugu are a few Antiaris toxicaria and Dialium holtzii in the Msimbazi valley. There are even fewer tall emergents in Kazimzumbwi, and Ruvu South is characterized by extensive Zanzibar–Inhambane scrub-forest that may be natural climax vegetation. There are also large stands of riparian forest in Ruvu South, as well as at least two swamps and areas of grass-covered flood-plain. The site has two major railway systems passing through it; the need to protect embankments and cuttings should help ensure some forest remains on the steeper slopes.Vikindu Forest Reserve (1,599 ha, much of which is plantation), to the south of Dar es Salaam, was known to hold Anthus sokokensis, but is so badly degraded that attempts to protect it were abandoned and it has not been included in this site.
See Box and Tables 2 and 3 for key species. Circaetus fasciolatus is a low-density resident. Anthus sokokensis is known from Ruvu South, but can only be a rare, low-density species. Zoothera guttata is a regular passage migrant, particularly in May when birds are moving north from their southern breeding grounds. Sheppardia gunningi is a locally common resident at all three forests and Ruvu South may hold Tanzania’s largest population of this species. The forest birds of Pugu and Kazimzumbwi are well known. Those of the forest of Ruvu South have received far less attention, but the avifauna of the woodlands is better known and includes such localized species as Glaucidium capense, Neafrapus boehmi, Pachycoccyx audeberti, Campethera bennettii and Pyrenestes minor, as well as uncommon migrants such as Coturnix chinensis. Pogonocichla stellata is a regular migrant from montane habitats. Other visitors from higher altitudes have included Sarothrura elegans, Columba larvata, Coracina caesia, Zoothera gurneyi and Andropadus milanjensis. Regular Afrotropical migrants include large numbers of Cossypha natalensis (which is also a low-density resident) and small numbers of Pitta angolensis. Trichastoma rufipennis puguensis is locally endemic.
Non-bird biodiversity: A population of Loxodonta africana (EN) is associated with Ruvu South and may well move between this site and the northern approaches of the Selous Game Reserve.
Pressure/threats to key biodiversity
The close proximity to Dar es Salaam has always placed high pressure on these Forest Reserves. In addition, the Pugu Hills hold one of the world’s largest and most easily accessible deposits of kaolin. Maintaining forest on the hills is important for water-catchment management. Repeated illegal invasions of Kazimzumbwi Forest Reserve have been well publicized. The Wildlife Conservation Society of Tanzania, in conjunction with the Forest Department, CARE and WWF, are running a long-term conservation programme in the area. The extensive plantations of exotic Cassia and Eucalyptus within Pugu should be removed and replaced with indigenous trees. There are kaolin deposits under the Pugu Hills, the exploition of which would necessarily result in destruction of habitat.