| The Daxia River,a tributary of the upper reaches of the Yellow River,originates from the northeastern margin of the Qinghai-Xizang Plateau and flows into the Linxia Basin into the Yellow River.It is located at the junction of the Qinghai-Xizang Plateau and the Loess Plateau.Its natural environment has a typical transitional characteristic and its ecological environment is fragile.Therefore,studying the change of the forest vegetation in Daxia River Basin has important social realistic significance.Because in the Qin and Han dynasties,this area has been gradually brought under the dominion of the Central Plains dynasty,and the development activities within the Drainage Basin have also deepened.With the population increasing and land reclamation,human beings’ intervention to the forest vegetation in the basin has been continuously strengthened.During the Ming and Qing Dynasties,manly development activities in this area were fierce,which is an important period for the change of the forest vegetation in this area.The changes of the forest vegetation in Daxia River Basin during the Ming and Qing Dynasties are mainly influenced by both natural and man-made factors.Naturally,the temperatures in Ming and Qing’s Small Ice Age decreased during the Ming and Qing Dynasties,and the climate change caused the forest vegetation changing.Artificially,the Ming Dynasty began to implement a large-scale policy of resettlement and immigration,and the Daxia River Basin forest vegetation suffered even more because of the serious damage to the ecological environment deteriorating.By the Qing dynasty,with the continuous expansion of population size,the demand for various kinds of trees increased,and the destruction of the forest vegetation was even more intense.The changes of the forest vegetation in Daxia River Basin during the Ming and Qing Dynasties are the result of the comprehensive influence of climate,environment,policy,war and many other aspects.Forest vegetation plays a fundamental role in the development of society and economy,the special geographical environment decides the variety element of economy in this area,especially forest vegetation plays an important role in agriculture,animal husbandry and business,for agriculture tool mainly made of wood,the same as in animal husbandry,as to business,many products are coming from forest,and the forest products are being the supplement of social life among the people in this area. |
