Human Response to Climatic Events in the Dry Savanna, Africa

点击翻译按钮获取中文摘要

Field researches were conducted in Kenya, Niger and Benin to document the characteristics of human response to climatic change in dry savanna areas, Africa.Geography and history of tree utilization were investigated in Meru District extending on a northeastern foot slope of Mt.Kenya. In southern humid areas, Meru people used a number of tree species and they had more knowledge on traditional uses of trees. People newly settled in northern dry areas used less species and had slightly poor knowledge. Strategies for droughts, however, were included in the ways in which they use trees and shrubs in their shambas in dry areas.An ecological linkage between environmental changes and socio-cultural profile of cattle keepers were studied in Marsabit Distrct, northern Kenya. Samburu people had their own risk-avoiding systems, and survived the past severe droughts.Development of eroded landscapes during the last 40 years was reconstructed in tributary drainage basins of the Niger, southwestern Niger. Soil erosion had been accelerated for the past 20 yesrs owing to deforestation in the surrouding area. The land degradation caused lack of crop fields and damaged fishery alog the Niger River. They were bewildered by the emerged environmental problems and started talking measures to cope with the situation.To clarify the recent trend in climatic change and the interaction between atmosphere and land surface, collected meteorological data were analyzed and soil moisture were observed in Niger and Benin along a cross section from arid region (Sahel) to humid region (Guinean coast). Soil moisture incresed continuously during rainy seasons owing to reduced rainfall intervals. No significant difference in soil moisture was detected in dry seasons among three observation sites with different annual precipitation. The observed moisture ranged from 1 to 5 percent in the seasons.