我国北方农牧交错带的环境演变

中国北方农牧交错带在１０～８．５ｋａＢ．Ｐ．经历了三次阶段性增暖后进入全新世暖期。８．５～８．０ｋａＢ．Ｐ．和４～３．５ｋａＢ．Ｐ．暖期的开始与结束事件中降水变化落后于温度变化３００～５００ａ；暖期盛期时的年均温较现代高２～３℃，降水多１００ｍｍ左右；暖期中存在多次短期寒冷事件，年均温最冷时较现代低３℃以上。３．５ｋａＢ．Ｐ．以来冷干趋势之上叠加着大致由３００ａ稳定与５００ａ波动构成的约８００ａ的周期性变化。全新世暖期原始农业文化的阶段性发展与暖期内环境波动相对应；暖期结束时发生了由农业向牧业文化转换的事件；暖期以后的冷干期为农牧交错文化时期，农业经济随冷干程度的变化而兴衰

ENVIRONMENTAL CHANGES IN THE NORTH CHINA FARMING GRAZING TRANSITIONAL ZONE

The North China farming grazing transitional zone, driven by the rainfall fluctuation, is one of the ecotones sensitive to global changes. The Holocene environment change was in three stages: (1) The obviously warm trend with the abrupt temperature rise in three steps during 10～8.5kaB.P.; (2) The Holocene Megathermal Period. The abrupt changes of warm wet at 8.5～ 8.0kaB.P. and cold dry at 4.0～3.5kaB.P. marked the beginning and ending of this period. The changes of precipitation were 300～500 years lag behind the temperature changes, which is the distinctive feature of monsoon climatic system of China in responding to global change. The temperature was 2～3℃ higher in maximum, and the precipitation was about 100mm more than present during this period. Several cold events are identified out during this period, with the temperature dropped down 3℃ more at maximum than the present. (3) The cold dry trend after 3.5kaB.P.. The climate changed in the quasi period of 800 years with 300 years relative steady warm and 500 years strong oscillation. The pre historical cultures in the North China farming grazing transitional zone were strongly impacted by the environment change. The primitive farming culture were developed and flourished in the Holocene Megathermal Period. The farming culture changed to the pastoral culture at the termination of the Holocene Megathermal Period. The farming grazing culture formed during the last 3500 years.