黄土高原环境异质性与植被的恢复与重建

Environmental heterogeneity and revegetation on the Loess Plateau

黄土高原是一个独特的地理区域,由于对其原生植被的不同认识,自然区划历来富有争议。为因地制宜地进行植被建设,在辨析植被属性有关论点(黄土无林、草原次生等)的基础上,主要由现代植被证据进一步讨论黄土高原的自然地带。分析了生物气候条件在不同地域之间的分异性,阐述了植被地带特征。为充分说明植被地带性,还从历史的角度探讨了植被建设的效果。表明黄土高原环境的非均质性可表征为森林、草原等地带,不能认为黄土高原不具有森林发育的地带性环境。相对于森林地带北界森林线,森林草原地带北界应为树木线。植被建设不应局限于一种土地利用模式,不能无视疏林及稀疏灌丛在森林草原地带的客观存在。

The Loess Plateau is a distinct geographical region, where natural regionalization has always been of much controversy because of variation in understanding its primary vegetation. In order to construct vegetation in line with local conditions, based on the discrimination on the viewpoints （no forests in the loess Plateau, secondary grasslands, etc. ） relevant to the vegetation property of the Loess Plateau, the paper further dealt with the natural zonation of the Loess Plateau by adopting modern vegetation evidences. After analyzing the regional differentiation of bioclimatic conditions and the vegetation zonal characteristics in the region, the author investigated the actual effects of the vegetation construction in history so as to fully illustrate the vegetation zonality. It is shown that the Loess Plateau might be regionalized into several different vegetation zones of forest and steppe for no homogeneity of its environment. The opinion that the zonal environment for forest growth is not possessed in the Loess Plateau is accordingly inadequate. So far as the north demarcation line for the forest zone is called forest line, the north demarcation line for the forest-steppe zone should be called tree line. The vegetation construction shouldn＇t be confined to such a land use pattern as ＂the 28-word general plan＂ put forward by Zhu Xianmo. The objective reality of thin woods and sparse shrubberies in the forest-steppe zone should not be ignored. At last, some other issues deserving attention and research were also presented.