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

该研究项目力求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）调查了库塞卜河流域环境变化与枯树的关系。认为洪水淤积和环境变化对枯树的影响。（2）从宏观和中观尺度上阐明了控制纳米比亚稀树草原植被结构变化的因素。纳米比亚各种稀树草原类型的地理分布主要受两个与年降水量无关的不同因素控制：土壤的持水能力和莫帕内的生态特征。（3）研究了纳米布沙漠库塞布河流域的古水文环境变迁。为了评价古环境条件，对库伊塞布河中游的河流地貌和各地貌面的土壤剖面进行了研究。（4）调查了纳米布沙漠雾的成因。白天，由于海风的影响，相对湿润的空气向内陆移动，到了晚上，由于辐射冷却，空气凝固。水汽使雾流动，雾被陆风吹向向西。

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.