摘要：
十六国时期夏国都城——统万城位于陕西省靖边 县城北无定河北岸，今天的自然景观属 于沙漠，仅存稀疏的次生灌丛和草本群落。但是，在约1600年以前，当地为温带干草原， 在塬面或山丘上分布有侧柏林，沟谷、河岸边生长喜温湿的乔木，河流、湖泊、沼泽中水生 植物繁盛，在丘间低洼处或盐碱土上分布有灌木和草本植物。当时该地区的年平均温度为7 8℃～9.3℃,最热月平均温度23.0℃～24.9℃，最冷月平均温度-12℃～-5.6℃，年 较差285℃～38.2℃，年 降雨量403.4～550.0 mm，最大月降雨量83.8～123.9 mm，最小月降雨量为4.4～1 2.2 mm。 当时的年平均温度比现在高出0.2℃～0.7℃，年降雨量也高出60～100 mm。如此的历史景 观今天 已经向南迁移，侧柏林或森林草原退缩至延安以南。在此近 1600年的时间里，毛乌素沙漠 分布范围不断扩大，其南部边缘推进了约200 km，推测沙漠扩展的速率达到平均125 m/ a。
Abstract:
Tongwancheng,the capital of the Great Xia King dom during the period of Five Hu and Sixteen Kingdoms in the Chinese history，wa s situated on the north bank of Wudinghe River in the north of Jingbian County ，Sh aanxi ProvinceThe recent Tongwancheng area has a desert landscape,with only s parse secondary shrub and grass communit yHowever，about 1600 years ago the Tongwancheng area was once a beautiful plac e of dry steppes with the landscape of s parse forestThere was a temperate vegetation F orests of Platycladus orientalis were distributed on the hills and uplands Therm ophilous trees grew along river banks and in gulliesAbundant aquatic plants grew in rivers，lakes and swampsSaltloving shrubs and herbs covered the sali nized soilAt that time，the climate of the Tongwancheng area was as follows:t he annual mean temperature was 7.8℃～9.3℃，the hottest monthly mean tempe rat ure was 23.0℃～24.9℃ and the coldest monthly mean temperature was -12.0℃ ～-5.6 ℃，the annual mean temperature difference was 28.5℃～38.2℃，the annual prec ipi tation was 403.4～550.0 mm，the monthly maximum precipitation was 83.8～123.9 mm and the monthly minimum precipitation was 4.4～12.2 mmCompared with the pre sent c limate，the annual mean temperature and annual precipitation were respectively 0.2℃～0.7℃ and 60～100 mm higher It indicates that the clima te in the Tongwancheng area about 1600 years ago was slightly warmer and wetter th an the present timeThe similar vegetative landscape of dry steppes has moved southward The forests of Platycladus orientalis and forest steppe have moved to the southern part of Yan'an area It is estimated that the Mau Us Dese rt migrate d southward at a mean rate of 125 meters per year during the past 1600 yearsents in peat from Northeast China.Journal of Northeast Normal University,（4）：99～102
孙同兴 王宇飞 侯甬坚杜乃秋 李承森. 陕北统万城地区历史自然景观及毛乌素沙漠迁移速率[J]. 古地理学报, 2004, 6(3): 363-371.
Sun TongxingWang Yufei Hou YongjianDu Naiqi u Li Chengsen. Historical natural landscape of Tongwancheng area in northern Shaanxi Province and migration rate of Mau Us Desert[J]. JOURNAL OF PALAEOGEOGRAPHY, 2004, 6(3): 363-371.