Studies on the conservation status of some exploited endangered species in Rogati forest mount Kenya

Abstract

Ragati forest is situated in the south-western section of mount Kenya forest. Mount Kenya is recognized as a centre of plant diversity. It harbours rare endemic tree species and lianas. Man's extractive activities have led to a serious degradation of Ragati forest. This study analyzed the impact of use of two trees namely Ixora scheffleri ssp. keniensis a locally endemic tree which is globally rare and is recorded to occur in Ragati forest only and near-endemic tree vepris glandulosa recorded in Muguga forests and Ragati only. Liana species studied include Rourea thomsonii, Hippocratea sp.cf. Africana and Dalbergia lactea. These lianas are widely distributed in African but are over exploited in Ragati. Use of the selected plants in areas adjacent to Ragati Forest has been documented but the levels to which these plants are harvested, their population, environmental conditions under which they grow and the effect of distance from forest edge on their on their utilization has not been documented. The distribution, population structure and the impact of human use of these plants were recorded in an area of approximately 50km2. A total of 189 plots of 400msqu. Each were sampled using systematic sampling design. In Ragati the usefulness of the forest plants increased in the plant size. Much as the harvestable size of lianas is 3 to 4 cm, basket makers still preferred lians in the large size classes. The study plants suffered more human damage as compared to damage byanimals. Data gathered point out that rarity of forest plants is a direct result of over-exploitation in the past. Rouraa, Dalbergia and Ixoxa had high numbers of seedlings and saplings compared to the mature individuals. However in Ixora, seedlings and saplings were prevalent in the forest while in the shambas only mature individuals were encountered. Hippocratea had more mature individuals in the small size classes. Both Vepris and Hippocratea had few individuals in the middle size classes indicating that in future there may be no mother plants to perpetuate their population. Soil nutrients levels had an effect on occurrence of the study plants. A significant positive relationship was found between the presence of lianas and potassium levels. Vepris and Roures were significantly more common on soils with high magnesium levels and were also correlated with manganese levels. Local people in Ragati preferred baskets made from lianas as compared to the alternatives available. This necessitated the basket makers to move farther a field in search of lianas and the price for baskets also went up. Destruction of the habitat through creation of farms was found to have negative effects on occurrence of the study plants and has contributed to rarity of the Ixoxa. Studies on length increment of Rourea revealed that it takes about 22 years to reach maturity. Therefore local people should be encouraged to develop alternative materials such as Napier grass, bamboo sterms and synthetic materials for use in basketry as opposed to lianas. Recommendations for sustainable use of forest resources are given.