中国北方农牧交错带人类生存环境的过去、现在和未来

THE PAST,PRESENT AND FUTURE OF HUMANLIVING ENVIRONMENT IN THE ALTERNATEZONE OF FARMING AND ANIMALHUSBENDRY of NORTHERN CHINA

中国北方农牧业交错带是我国生产最不稳定的地带，风、旱、冻、雪等灾害频繁出现，具有敏感而脆弱的人地关系。文章在研究了该地带人类生存环境的演化及其规律的基础上，对未来百年人类的生存环境作了预测。

The alternate zone of farming and animal husbandry of the Northern China is the best unstable zone of production in our country.It is the zone which windstrom,drought,flood disaster, freeze injury and snow disaster are frequent occurrence.It has a changeable and unstable natural condition. It also has the sensitive and fragile relationship between the human and the land.Study the evolution of the human living environment and find out the past regular and future evolution trend have an lmgortant theory and practice significance.1.PAST EVOLUTION OF THE HUMAN LIVING ENVIRONMENT SINCE THEHOLOCENE 1)The regional palaeosoil and peat layers are the sign of relative warm and humid stage.From the western Ordos Plateau to the eastern Kerlqin Desert inthe area developed 3-5 palaeosoil layers. The Daihai and Huangqi lake basin in the middle part of the area deposited 3-5 peat layers. Their developing periods were 11000-10000,8500-8000,6500-6000,4500-4000,2500-2300 and after 2000 aB.P..2)The melt-frozen folded layers are the sign of the dry and cold climate.The typical example is the Daihai area,where five melt-frozen folded layers have been found. The periods of them were 12000-11000, 9500-9000, 5500-5000, 2300-2000 and 1500-500aB.P..3) Palaeovegetation and ostracoda assemblage shows the environment evolution.The early Holocene climate was cool and dry. It's low temperate stage was 2°-3°C lower than present.The middle Holocene climate was relative warm and humid, It's high temperate stage was 3°C higher than present annual average temperature.The late Holocene was temperate and semi-arid climate and similar to the present.4)The change of hydrology of lake and environment evolution in the high lake level stage was similar with optimum period(8000-5000 aB.P.).It's about five times lake transgression and regression were synchronism with the climate chang of cold and warm.5) The evolution process of human material culture was closely related with the environment evolution.There are the Yangshao Culture and Longshan Culture in the western and middle part of the area, while the Xinglongwua Culture, Hongshan Culture and Bronze Culture in the eastern part, and the Ironware Culture was found in the most plsces. The development process of these human material civilazation was closely related with the environmental evolution process.2.GENERAL SITUATION OF THE HUMAN LIVING ENVIRONMENT IN PRESENT SINCE 50-90 AGES The principal climate is the semi-humid to semi-arid climate of the middle temperate zone in the alternate zone of farming and animal husbandry in the northern China.The distribution of annual average temperature was increased from northeast to southwest.The annual average temgerature is-4℃ in the north of Da-Xing-An Mountain, 6℃ in the south of Chifeng City,and 8℃ in the west of Alashan. According to statistics,there was a marked drop in temperature before 1960's and reached to the minimal point in 1970's,then sppears a rising tendency from 1980's to now. The change tendency is similar to the long-term tendency of temperature change in the northern Hemisphere. But contrary to the temperature's change, the annual precipitation declines from southeast to northwest.The 250mm line of Precipitation runs across the whole region. The Precipitation was greatly declined in 1960's than the before, and despite of a increasing in 1970's,a great decline appeared again in 1980's. So an abviously tendency of drought was appeared in the past few years,which caused the catastrophic effectfulness,such as the dilating of drift sand,the degenerating of meadow and soil,the lessening of productivity and the increasing of the disaster of drought and waterlogging.3.PREDICTION OF THE HUMAN LIVING ENVIRONMENT IN THE TEN ANDNEXT HUNDRED YEARS The development tendency of the next hundred years in the Ordos region will be the relative dry period around 2000's and 2040's, and the relative humid period will be the end of this century, around 2020's and 2080's. The precipitation of the relative humid period will be 12% higher than P