STUDIES ON THE ENVIRONMENTAL CHANGE AND HUMAN ACTIVITIES IN SEMI-ARID AREA OF AFRICA

该研究项目旨在确定纳米比亚半干旱地区自末次冰期以来的环境历史，以及最近的环境变化，包括气候、地形、植被、土壤、土地利用和农业的变化。(1)调查了库伊塞卜河流域环境变化与枯死树的关系。人们认为，洪水淤积的泥沙和环境的变化对枯死树木有影响。(2)从宏观和中尺度上阐明了纳米比亚热带稀树草原植被结构变化的控制因素。纳米比亚各种稀树草原类型的地理分布主要受两个独立于年降水量的因素控制：土壤的持水能力和莫潘的生态特征。(3)对纳米布沙漠古水文环境变化进行了研究。通过对库伊塞卜河中游河段河道地貌及各地貌面土壤剖面的考察，初步确定了库伊塞卜河中游河段的古环境条件。在纳米布沙漠调查了雾的来源。白天，海风使相对湿润的空气向内陆移动，夜间通过辐射冷却而凝固。水蒸气带着雾，被陆风吹向西。

This research project sought to determine the environmental history of the semi-arid area of Namibia from the Last Glacial stage, and recent environmental changes, including changes in climate, topography, vegetation, soil, land utilization, and agriculture.(1)The relationship between the environmental change and the dead tree was surveyed in the Kuiseb River basin. It was considered that sand deposited by flood and change of environments affected the dead trees.(2)Factors controlling the changes in vegetation structure of savanna vegetation in Namibia were clarified in macro-and meso-scale. The geographical distribution of the various savanna types in Namibia was principally controlled by two different factors that are independent of the amount of annual precipitation : the water-holding capacity of the soil and ecological characteristics of Mopane.(3)The paleohydorological environmental changes of the Kuiseb river basin was investigated in Namib Desert. The fluvial land forms and the soil profiles on each geomorphic surface were examined at middle course of the Kuiseb River in order to estimate the paleoenvironmental condition.(4)The origin of the fog was surveyed in Namib Desert. In the daytime, the air which is comparatively moist because of sea breeze moved to the inland, and it is solidified by radiative cooling in the night. The water vapor runs the fog and it is blown by the land wind to the westward.