Dzombo Hill Forest (6400)
Kenya, Africa
Site overview
KBA status: confirmed
Year of last assessment: 2004
National site name: Dzombo Hill Forest
Central coordinates: Latitude: -4.4333, Longitude: 39.2000
System: terrestrial
Elevation (m): 100 to 470
Area of KBA (km2): 5.73176
Protected area coverage (%): 81.92
KBA classification: Global/Regional TBD
Legacy site: Yes
Site details
Site description: Dzombo hill, like Mrima (IBA KE018), is an igneous intrusion into the Triassic sandstone of the surrounding coastal plain. The hill rises abruptly to around 470 m, with a lower summit at 400 m to the west. The rainfall is 900–1,100 mm/year, with considerable additional mist and dew on the upper slopes. Dzombo is covered by undifferentiated coastal mixed forest, wettest on the south-eastern slopes. To the north and north-west, the forest grades into drier woodland and scrub. Large trees include Combretum schumannii, Lannea welwitschii, Cola clavata, Ricinodendron heudelotii, Scorodophloeus fischeri, Tamarindus indica, Newtonia paucijuga, Sorindeia madagascariensis, Diospyros mespiliformis and Manilkara discolor. Dzombo was designated as a Forest Reserve in 1941, and Kaya Dzombo as a National Monument, within the Forest Reserve, in 1992. The forest is considered sacred by the local community, with the grave of a Digo ruler, or Kubo, near the summit.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance because it meets one or more previously established criteria and thresholds for identifying sites of biodiversity importance (including Important Bird and Biodiversity Areas, Alliance for Zero Extinction sites, and Key Biodiversity Areas) KBA identified in the process of compiling the 2003 CEPF Ecosystem Profile of the Eastern Arc Mountains and Coastal Forests Hotspot (which was later [in 2005] split into two Hotspots, the East Afromontane and the Coastal Forests of Eastern Africa). Species taxonomy and threat category was based on IUCN Red List 2002.
Additional biodiversity: See Box and Table 2 for key species. The globally threatened and restricted-range Anthus sokokensis has recently been discovered, and is presumably resident. Dzombo has a rich avifauna, with 35 forest-dependent species recorded; more are likely to be listed with further surveys. Regionally threatened species include Stephanoaetus coronatus. Non-bird biodiversity: The threatened small mammal Rhynchocyon petersi (EN) occurs; it is restricted to a small number of East African coastal forests. Dzombo holds a number of rare plants, with 36 taxa listed as rare in Kenya, including the endemic Ziziphus robertsoniana and an undescribed species of Uvariodendron.
Habitats
Land use: agriculture | forestry | tourism/recreation | water management
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Shrubland | 50 | |
| Forest | 50 |
Threats
Summary of threats to biodiversity at KBA: Dzombo is designated as a National Monument and considered sacred by the local community. This affords it some protection. However, it is increasingly under threat from agricultural encroachment (which is already considerable), unsustainable timber and pole extraction, bark stripping of trees for binding materials, and firewood collection. At present, vehicle access into the forest is difficult and Forest Department control is minimal. The steep topography of this site probably discourages commercial loggers from exploiting it, although there has been heavy poaching of Combretum on the lower slopes for splitting into building poles. In the longer term, encroachment is likely to become the most serious threat as the demand for land increases. In the past, fire has been used to open up this site for easy clearing for agriculture; frequent fires on the south-western slopes have turned forest into grassland.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Natural system modifications | Fire & fire suppression | Trend Unknown/Unrecorded | Ongoing |
| Biological resource use | Gathering terrestrial plants | Unintentional effects (species being assessed is not the target) | Ongoing |
| Agriculture & aquaculture | Livestock farming & ranching | Small-holder grazing, ranching or farming | Ongoing |
| Invasive & other problematic species, genes & diseases | Invasive non-native/alien species/diseases | Named species | Ongoing |
| Human intrusions & disturbance | Recreational activities | Ongoing | |
| Human intrusions & disturbance | Work & other activities | Ongoing | |
| Climate change & severe weather | Droughts | Ongoing |
Additional information
References: Mlingwa et al. (2000), Mungai (1985), Robertson and Luke (1993), Waiyaki (1995), Waiyaki and Bennun (2000).