Study area

Arabuko Sokoke Forest is the largest surviving single block of previously extensive indigenous dry coastal tropical forest in Eastern Africa. It is situated in Coastal Kenya at, 3° 20’ S and 39° 50’ E, 7 km inland from Watamu between Kilifi and Malindi and 110 Km North of Mombasa (Figure 1).

Figure 1: Map of the study area and location of sampling points along transects. Location of Arabuko Sokoke Forest between Kilifi and Malindi. Label 1 shows two adjoining transects and points located in Cynometra thicket and relatively open Brachystegia woodland, 2 shows a transect and sampling points in Mixed Forest and label 3 shows point counts along transects in planation forest and farmland. Farmland is characterized by low vegetation cover and a road and footpath network.

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Arabuko Sokoke Forest was proclaimed a Crown Forest in 1932 and gazetted as a forest reserve in 1943 during the colonial period. It was gazetted as a strict nature reserve in the 1960s (Fishpool & Evans 2001), under the colonial government. Within the forest area about 4,300 ha was designated as a strict Nature Reserve in 1977. The total area of the forest is approximately 41,600 ha and the protected area was extended in 1979 by 1,635 ha (Kenya Wildlife Service 2013). Arabuko Sokoke Forest is surrounded on all sides by village communities. There is a total population of about 104,000 people around the forest, with 54 villages actually bordering on the forest (Kenya Wildlife Service 2013). Levels of unsustainable forest use have intensified, with increasing human populations resulting in higher levels of resource degradation; since traditional subsistence use of Arabuko Sokoke Forest predates its gazettement as a reserve. Human impact on the forest can be dated to 1900 when the Mijikenda people settled around the forest (Robinson & Bennett 2000; Githitho 2004). Deforestation of East African coastal forests was estimated at 139.17 Km2 over a 7 year period between 2000 and 2007 (Birdlife International 2013). It estimated that 66% of the coastal forest in East Africa, including Tanzania was lost between 1990 and 2011

(Birdlife International 2013). There were no corresponding data for most of the other Kenyan coastal forests. However, indications are that large tracts of coastal forests continued to be lost through charcoal extraction and conversion to agriculture e.g. pineapple farming in Dakatcha Woodlands (Birdlife International 2013).

At present, most subsistence use is illegal, although in practice it cannot be controlled by regulation alone. Local households depend on the forest for domestic use through direct harvesting for fuel-wood, building poles, mushrooms and bush-meat; and commercial use

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through products such as carving wood, poles, butterflies and honey. Arabuko Sokoke Forest is rapidly gaining a reputation in ecotourism for tourists who have interest in birds. It has attracted tourists since the early 1970s, and currently specialist birdwatching tourists regularly visit the forest, and the number of such visits is increasing (Kenya Wildlife Service 2013).

More than 260 bird species have been recorded within the protected area (Jackson 2008), although this includes waterbirds which were effectively excluded from this study. The avifauna includes six globally threatened species: Clarke’s Weaver (Ploceus golandi), Sokoke Scops Owl (Otus ireneae), Amani Sunbird (Anthreptes pallidigaster), East Coast Akalat (Sheppardia gunningi), Spotted Ground Thrush (Zoothera guttata) and Sokoke Pipit (Anthus sokokensis). While the forest is a protected area, the surrounding region has been subjected to intense land use change including plantations and subsistence agriculture. Arabuko Sokoke Forest is under the management of Kenya Forest Service and Kenya Wildlife Service. It consists of three distinct vegetation types; Mixed Forest, Brachystegia woodland and Cynometra.

Mixed Forest is relatively dense, tall and undifferentiated, with a high diversity of tree species (Plates 1 and 2). It has a diverse tree flora including Afzelia quanzensis, Hymenaea verrucosa, Combretum schumannii and Manilkara sansibarensis and the cycad Encephalartos hildebrandtii. It extends on the wetter coastal sands in the east of Arabuko- Sokoke to about 7,000 ha, forming 16.8% of the total forest cover. Brachystegia woodland runs in a strip through the approximate center of the forest, it is relatively open with

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relatively large trees and dominated by Brachystegia spiciformis (Plates 3 and 4). It covers about 7,700 ha on drier and infertile white sands through the centre of the forest and contributes 18.5% of the total forest cover. Cynometra thicket is dense, and almost impenetrable on red Magarini sand (Plate 5). It extends on the North-West side of the forest, covering about 23,500 ha. It forms a proportion of 56.5% of the whole forest cover. It is dominated by trees of Cynometra webberi and Manilkara sulcata, and the euphorbia species Euphorbia candelabrum. Brachylaena huillensis also used to be abundant in this zone, but its numbers have been severely reduced by extraction (Kenya Wildlife Service 2013; Arabuko Sokoke Forest Management Team 2002).

The plantation forest is under the management of Kenya Forest Service. Major portions of plantation forest consisted of trees for commercial timber including Eucalyptus sp. and Casuarina sp. (Plates 6 and 7). Wide gaps and open areas due to logging and clearing characterize the plantation forest. A small portion of the plantation area was still under indigenous tree cover. Farmlands are characterized by subsistence agriculture; bush clearing, burning, logging of trees, annual crops and few tree stands (Plate 8).

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Plate 1: Mixed Forest vegetation on sand & clay

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Plate 3: Open Brachystegia woodland on poor sandy soil

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Plate 5: Impenetrable Cynometra thicket on red sand

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Plate 7: Eucalyptus plantation adjacent to the primary forest

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