黄土高原古植被与再造山川秀美

Paleo-vegetation of the loess plateau and its reconstruction,northwestern China

要想恢复秀美的山川,主要在于恢复被人类严重破坏的原始植被。黄土高原的原始植被到底是什么样子,学者们说法不一。孢粉分析是最重要的方法。目前,研究结果已揭示出黄土高原古植被在第四纪以来显示着时间上、空间上的变化。古土壤代表间冰期夏季风盛行的湿热气候,植被比较繁盛;黄土代表冰期冬季风盛行的干冷气候,植被凋凌。全新世中期5000～6000年前,现代间冰期气候最佳时期,半坡人生存之时,森林茂密并有亚热带植物入侵,但兰州一带1万年来一直保持着荒漠草原的面貌。因此,黄土高原植被的恢复应参照各地的原始植被并考虑现代气候条件,因地制宜地实施。在东南部可以恢复森林,中西部可以恢复森林草原,西北部只能种草恢复草原。

The beautiful landscape of the loess plateau in northern China could be primarily reconstructed by means of restoration of its original vegetation that was currently lost due to mankind's destruction. The first task to do so involves clarifying the contentious type of the original vegetation through pollen spore analyses. Temporal and spatial changes of the paleo-vegetaion types in the loess plateau were figured out in terms of previous specific pollen spore-based studies. The paleo-soil was the product of the warm and humid climate predominated by the summer monsoon during the interglaciation, implicating a luxuriant period of vegetation, whereas the loess was related to the arid and cold climate predominated by the winter monsoon during the glaciation, indicating a withering period of vegetation. During the Banpo man time or in the Middle Holocene, 5 000～6 000 Bp, the climate within the modern glaciation best fitted vegetation and the intrusion of some sub-tropic trees was postulated to have taken place. Yet the Lanzhou area, Gansu Province, kept being desert or steppes for past (10 000) years. Consequently, the reconstruction of vegetation to its primary state should be principally implemented in consideration of its original distribution. Specifically, the southeast part of northwestern China should starts with forest and the middle part better with both forest and steppes while the west part can only be constructed as steppes.