山地自然条件远比平原区复杂,这是大家所公认的。作者自六十年代初以来,在北京山区较系统地开展了山区土地类型调查、制图等研究工作,对山区土地分异因素、土地分级和分类等问题,进行了初步探索。

Aspect is a significant feature in mountain geography. It is one of the factors that ause the differentiation of mountain landscape and diversity of land use in mountain region. In ancient Chinese literature it is known as the "yinipo" (shady slope) and ""yangpo" (sunny slope). The equivance of these terms have also beging found in the geographical literature of many countries.The basic element that leads to the differentiation of the landscape is climate, e.g. -solar radiation, temperature, humidity are different on different aspects. Under the in-fluence of climate, other physical attributes such as vegetation, soil, hydrology and land-torm are manifested. The differentiation of landscape is the result of the interaction of these physical features.The difference of physical characteristics of the aspect is also significant in econo-mic activities, e.g. agriculture, forestry, husbandry and engineering. In classification of land types aspect shoud also be. considered.