Eastern Arc Mountains, Kenya

Description

The Eastern Arc Mountains are part of the larger Eastern Afromontane Biodiversity Hotspot which is ranked ninth in the world. They are ancient crystalline mountains uplifted 30 mil-lion years ago stretching from the Taita Hills in Kenya to the Udzungwa Mountains in Tanzania.

About thirty million years ago, the area was covered by extensive rainforest. During a cooler and drier period some ten million years ago, the lowland forests were converted to savanna, leaving the mountain ranges as "islands" where the tropical forests continued to flourish. The isolation of each mountain range has led to a great deal of endemism, and a very diverse flora and fauna.

The Taita Hills are located in southeast Kenya, 38°08'E; 03°15'S and 38°45'E; 03°51'S, within Taita Taveta county. These ranges are divided into the Dabida, Sagala, and Kasigau massifs. Dabida is separated from Sagala and Kasigau by a semi-arid plain, 20 km and 50 km away respectively. Mbololo (220 ha) and Kasigau are the largest and most pristine of the Taita Hills forests.

Justification de la Valeur Universelle Exceptionnelle

The list of unique animals found in Taita includes two Critically Endangered birds - the Taita Apalis and Taita Thrush, Taita Hills Purple-glossed snake, Sagalla caecilian (Endangered), Taita Warty frog, Taita Blade-horned chameleon (Near Threatened) and three endemic butterflies. The hills are also home to the Taita falcon, Abbott’s starling, Taita White-eye, the Southern Banded Snake-eagle and the Taita Mountain Dwarf Galago.

Plants include the African violet, Ocotea kenyensis (Stinkwood), and Coffea fadenii (wild coffee). Other characteristic trees are Tabernaemontana stapfiana, Maesa lanceolata (growing especially where the forest has been heavily disturbed), Albizia gummifera, Chrysophyllum gorungosanum, Cola greenwayi, Macaranga conglomerata, Newtonia buchananii, Syzygium sclerophyllum, Xymalos monospora and the palm Phoenix reclinata. There are 17 plant species endemics to these hills including Ceropegia verticillata, mpatiens engleri subsp. pubescens, Impatiens teitensis, Zehneria tuberifera, Euphorbia classenii, and Streptocarpus teitensis.  It is further noted that the flora of Taita Hills includes 83 species that are globally threatened with extinction.

Taita hills forests are a designated Important Bird Area and also a Key Biodiversity Area. These distinctive characteristics make the forests a habitat for some of the highest levels of endemism of animal, bird and plant species in the world, justifying the need for its conservation. 
 
Mbololo
The Mbololo forest located at the northern end of the Dabida Massif, 03º19’S 38º27’E comprises c. 220 ha of moist forest, mainly towards its northern end, between c. 1400 m and the peak at 2,209 m. The vegetation comprises high canopy forest with Albizia, Macaranga, Strombosia and Newtonia trees. The lower canopy comprises Aristogeitonia, Agarista, Maesa, and various Psychotria species while tree-ferns abound along the sides of several streams. This forest is the sole location for the Taita violet (Streptocarpus teitensis) and the Taita Warty frog.  It is estimated to hold 78 % of the world population of Turdus helleri - a Taita forest endemic bird.

Mount Kasigau
Mount Kasigau is located in Taita Taveta county at 03º49’ S, 38º40’ E, 115 km2. Its vegetation includes montane forest in the upper reaches and Acacia-Commiphora bushland at the base. Nyangala, the summit at 1641 m, has exposed basement granitic gneiss which also forms vertical cliffs and ridges at different elevations. The mountain captures moisture from the north-east and the south-east monsoon winds blowing from the Indian Ocean, hence is a vital source of water for the adjacent communities.

Mount Kasigau in Kenya is potentially a vital region for biodiversity conservation as it supports many of the nearby Taita Hills endemic bird species. It is currently known to support a large population of the critically endangered species the Taita White-eye, Zosterops silvanus, and is believed to hold a small population of the globally critical species the Taita Thrush Turdus helleri.  Mt Kasigau was shown to be the species' main stronghold of the Taita White-eye, maintaining a very high density and holding 80% (5,600 individuals) of the entire population. The endemic plant, Euphorbia classenii occurs naturally only on mount Kasigau.

Criterion (vii): The ancient crystalline rocks that underlie the Taita Hills have over millennia of erosion resulting in a startlingly beautiful landscape with massive summits of Vuria, Yale and Wesu overlooking the forest fragments and countryside outside the selected forest blocks.  Mount Kasigau that stands 50 km south of the rest of the Taitas, rises majestically from 550 m to a densely forested/rocky summit at 1641m, while Mbololo ranges from 1400 – 1700m.  The summits of these forests offer unique opportunities for hiking, birding and other eco-tourism pursuits.

Criterion (x): The Eastern Ac mountains in Kenya are home of 27 endemic taxa of flora and fauna a large proportion of which are globally threatened with extinction. These include the Taita Apalis, Taita Thrush, Taita Hills Purple-glossed snake, Sagalla caecilian, Taita Warty frog, Taita Blade-horned chameleon and three endemic butterflies. The hills are inhabited by the Taita falcon, Abbott’s starling, Taita White-eye, the Southern Banded Snake-eagle and the Taita Mountain Dwarf Galago. There are 17 plant species endemics to these hills including Ceropegia verticillata, Impatiens engleri subsp. pubescens, Impatiens teitensis, Zehneria tuberifera, Euphorbia classenii, and Streptocarpus teitensis.  It is further noted that the flora of Taita Hills includes 83 species that are globally threatened with extinction.

Déclarations d’authenticité et/ou d’intégrité

The Taita Hills Eastern Arc Properties (Mbololo and Mt. Kasigau) are well-protected as forest reserves, indeed there are no human settlements or deleterious anthropogenic activities there-in. They are jointly managed by the Kenya Forest Service and the County Government of Taita Taveta.  In addition, Mbololo is one of few forest properties whose management is under official documented collaboration of County and National governments, though anthropogenic pressures persist.

Comparaison avec d’autres biens similaires

The Eastern Arc Mountains, Kenya is similar to Eastern Arc Mountains Forests of Tanzania, which are on the Tentative List for the united Republic of Tanzania. They have similar patterns of species endemism, species diversity and geomorphology. It is particularly remarkable that each Eastern Arc Mountain tends to have species endemic to them, thereby demonstrating the need to conserve each component for posterity.