辽西北地区全新世中期以来环境变迁

ENVIRONMENTAL CHANGE IN THE NORTHWEST AREA OF LIAONING PROVINCE DURING THE MIDDLE HOLOCENE

通过对辽西北牧场泥炭层孢粉含量分析 ,结合14 C及辽西北地区其他地质记录 ,初步重建了辽西北地区全新世中期以来 ,即 5 0 0 0aBP以来的环境演变序列 :5 0 0 0～ 4 4 0 0aBP为冷干 ,但气候仍较今日适宜 ,辽西地区这时为森林草原景观 ;4 4 0 0～ 2 75 0aBP以温暖湿润为主 ,后期气候稍冷 ;2 75 0～ 10 90aBP以冷干为主 ,后期稍温润 ;10 90～ 2 5 0aBP以干旱为主 ;2 5 0aBP至现在辽西地区环境进一步向干旱化方向发展。辽西北地区环境变化的不同阶段可与当地人类发展对应 ,温暖湿润的环境使农业得以发展 ;反之 ,寒冷干燥、环境恶化 ,以牧业为主 ,人民生活受到限制。

The northwestern area of Liaoning includes northwestern Liaoning Province and a part of the eastern Inner Mongolia. This area,which is located in the agriculture-pasture interlacing zone in North China and also in the transitional zone of ecological systems, is sensitive to global changes.After middle-late Holocene, the culture deteriorated consistently due to climate fluctuation and human activities.Based on pollen analysis of Muchang section which is of high resolution in the northwest area of Liaoning Province,together with other geological records,the authors reconstructed the history of paleoclimatic changes in this region from about 5 000 aBP. During the last 5 000 years, the area of northeast Liaoning experienced alternations of relative warm-wet and relative cold-dry periods. Three evident cold-dry and one warm-wet periods were identified. The authors divided the environmental change into four stages,namely,5 000～(4 000 aBP,) 4 400～2 750 aBP, 2 750～1 200 aBP,and 1 090 aBP-present. The climate of the first and third stages were temperate and wet, the second was relatively cold an dry,and the climate of (1 090 aBP-present) developed further towards aridity. The change of environment and human activity can be compared with each other. In the northwest area of Liaoning Province, the warm and moist environment contributes to agricultural development. On the contrary, the cold-dry climate causes the regional environment to be deteriorated.