关键词: 自然地带, 综合自然区划, 干草原, 黄褐土, 陕西, 干燥度, 带层, 山地垂直自然带, 风沙化, 焦土

Abstract: The division of natural zones is decided by the features of all round natural conditions.Since the formation of natural zones is mainly controlled by zonal factors, taking climatic conditions into consideration, heat, water, soil, vegetation and the characteristics in agricultural production should be regarded as criteria in the division of natural zones.Because these phenomena are mirrored in the soil, vegetation and agricultural dif-ferentiation, Shaanxi province can be divided into following eight natural zones:(1) Sub zone of semidesert steppe-brown desert steppe soil;(2) Zone of dry steppe covered by wind-blown sands-light chestnut soil;(3) Zone of dry steppe-light-textured heilu soil;(4) Zone of forest steppe-gray forest soil and argillaceous heilu soil;(5) Zone of semi-arid deciduous broad-leaf forest and forest steppe-drab soil;(6) Zone of mixed forest of coniferous and broad-leaf trees-burozem and drab soil;(7) Zone of deciduous broad-leaf forest and evergreen broad-leaf forest-Cinnamon Yellow soil and Brown Yellow soil;(8) Sub Zone of evergreen broad-leaf forest-Yellow earth. Of course clear boundary lines do not always exist, since one natural zone may shade into another.