ケニア共和国グレートリフトバレー周辺に残存する 熱帯乾燥林・熱帯山地林の森林構造について

抄録

Various approaches are applied in forest surveys depending on their objectives, including inventory surveys and surveys based on measuring every tree. Phytosociological field surveys entail qualitative analyses of species and their dominance in each stratum, whereas cross-sectional schematics and physiognomic charts are often drawn to structurally and visually characterize forests. In this study, a phytosociological field survey was conducted and cross-sectional schematics were developed to analyse the height of each stratum, plant coverage, presence of an emergent layer, and number of species per survey section for various forests along the Great Rift Valley that cuts from the north to the south across the Republic of Kenya. Structural characteristics of forests in each areas were organised, including the Tinderet area where forest vegetation height is significantly tall; the Nairobi area, where the forest features low average tree height; Loita forest, where the tree layer has a high plant coverage with a large number of species per survey section; and the Marsabit and Mt. Kulal area, where the forest structure is characterised by five strata, including an emergent layer, but the number of species per survey section is significantly small. In Kenya, where the natural forest area is comparatively small relative to the area of the country, qualitative and structural recording of the few remaining areas of predominantly natural forests is of pressing concern with respect to the responses to various issues concerning forests, as well as to conservation and regeneration activities in the locally unique forests.