These montane grasslands lie on the Kinangop Plateau, a wide stretch of land bounded by the forests of the Aberdare mountains (IBA KE001) and Kikuyu Escarpment (KE004) to the east and south, and by a steep scarp dropping to the Rift Valley floor on the west. To the west and north, the IBA boundary follows the 2,400 m contour. Rainfall averages c.1,000 mm/year, but the southern part is wetter than the north, which lies in the rain shadow of the Aberdares. The landscape is generally flat, sloping gently upwards to the base of the Aberdare mountains, but dissected by valleys bearing streams that drain into the Malewa and Karati rivers (see Lake Naivasha, KE048). Originally, the entire plateau was covered with almost treeless, tussocky grassland, including many tussock bogs in the swampy valleys. Characteristic tussock grasses include Andropogon amethystinus, Cymbopogon nardus, Digitaria diagonalis, Eleusine jaegeri, Eragrostis botruodes, Hyparrhenia hirta, H. tamba and Pennisetum hohenackeri. Since the 1960s the area has been settled by the Kikuyu people, whose livelihood revolves around small-scale farming. Large areas of land have been ploughed for cultivation (mainly maize, wheat, cabbages and potatoes) or to remove the tussock grass species, which livestock find unpalatable. Woodlots of introduced trees, such as Eucalyptus globulus, Acacia mearnsii, Pinus radiata and Cupressus lusitanica, now dot the landscape. Many of the wetlands have been drained, directly or by planting water-thirsty exotic trees.
See Box and Table 2 for key species. This is probably the world stronghold of Macronyx sharpei, a threatened Kenya endemic. The species is confined to grassland, preferring short-grass fields with tussocks, and in good habitat occurs at densities of 0.8 individuals/ha. Cisticola aberdare is thought to occur in the higher parts of the plateau, close to the Aberdare mountains, but its status is uncertain. Circus macrourus occurs on passage. The grasslands support a distinctive avifauna that includes localized species such as Vanellus melanopterus, Cisticola ayresii, Euplectes jacksoni (a seasonal visitor, nesting in tussock grassland and at times in wheat fields) and E. progne (a regionally threatened species). Large numbers of Palearctic migrants use the area on passage, notably Falco subbuteo, Buteo buteo, Ciconia nigra, Apus apus, Merops apiaster, Motacilla flava and Oenanthe oenanthe.
Non-bird biodiversity: The fauna and flora of these grasslands have been little studied. Very few large wild mammals survive on the Kinangop, but many smaller species that are confined to highland grassland can be expected. The frogs Hyperolius montanus and Phrynobatrachus kinangopensis and the snake Bitis worthingtonii are recorded only in Kinangop and a few other sites in the Kenyan highlands. Hyperolius montanus was considered secure in 1980, but it is a montane grassland species and may now be under threat.
Pressure/threats to key biodiversity
Kenya’s unique highland grasslands are not included in any protected areas, and are rapidly vanishing. The remaining grassland on the Kinangop Plateau is now mainly modified grazing land, sometimes in rotation with arable cropping. The ecological character of the plateau is changing remarkably fast. Destruction of indigenous forest on the Aberdare slopes, drainage of wetlands and afforestation with exotic trees has resulted in a warmer, drier climate, with less frequent frosts and less regular mist and rain. Less frequent frosts (and an unreliable milk market) has increased the attraction of crop cultivation rather than livestock rearing. A growing human population has put more pressure on the land, leading to smaller average land holdings (which tend to include proportionately less grassland) and higher stocking rates. In 2000, it was estimated that grassland covered just 50% of the plateau. In turn, only around 50% of this was tussock grassland, more than half of which occurred in patches too small to support territories of Macronyx sharpei. If present trends continue, it is estimated that within 10 years tussock grasslands will cover only about one-sixth of Kinangop, and all farms big enough to act as potential longclaw reserves will have been subdivided to smaller sizes. Macronyx sharpei seems able to coexist with livestock, provided that adequate tussock cover remains, but cannot survive in farmed fields: it requires grass tussocks for feeding, roosting and nesting. It is also severely affected by habitat fragmentation. Conservation of this IBA represents a major challenge. Further ecological and economic studies are urgently required to assess what land-use regimes are compatible with Macronyx sharpei conservation, and what economic opportunity costs these entail. Land should be purchased for a model Macronyx sharpei reserve that can fulfil an educational and demonstration function. Working with farmers’ cooperatives to improve milk processing and marketing opportunities would help to increase the economic returns from dairy farming. Fortunately, environmental awareness is growing in the area. A local conservation action group, ‘Friends of Kinangop Plateau’, now has active branches in three parts of the plateau. Parts of this IBA have now been well surveyed, but additional survey work is needed in the northern sector. There are reports of Macronyx sharpei at around 2,300 m near Lake Ol’Bolossat (c.18 km north-north-west of Wanjohi, at the IBA’s northern limit). If confirmed, these would make it appropriate to extend the northern boundary of the IBA. The presence of Cisticola aberdare at the base of the Aberdare mountains also requires confirmation.