科尔沁沙地麦里地区晚全新世植被演化

根据一个泥炭剖面高分辨率花粉资料序列,初步重建了科尔沁沙地麦里地区晚全新世的植被演化过程。在3100 a BP以前,该地以固定沙丘上生长的蒙古栎(Quercus mongolica Fisch.)等阔叶疏林为主;以后随着半固定沙丘和流动沙丘增多,蒿属(Artemisia L.)和藜科等草本植物逐渐增加,而固定沙丘上的阔叶树则趋于减少。在1000～660 a BP期间,麦里地区几乎所有沙丘植物都经历了繁盛生长,蒙古栎种群的扩大尤其显著。3100 a BP以来植被和沙丘的演化可能同人类活动影响有直接关系,而1000～660 a BP期间的植物繁盛则由生长季雨量增加引起。花粉统计分析还表明,在森林草原等生态过渡带,花粉浓度和花粉沉积率比花粉百分比更好地指示了植被演化过程。

LATE HOLOCENE VEGETATION IN MAJLI REGION,NORTHEAST CHINA, AS INFERRED FROM AHIGH-RESOLUTION POLLEN RECORD

The change of vegetation in Maili region over the last 3 400 14C years has been reconstructed based on a high-resolution pollen record. It was thought that the contrast between arboreal and herb plants in different periods might well reflect the change in relative extent of the fixed sand dunes and active sand dunes, and the evolution history of the sand dunes could be thus investigated. Before 3 100 a BP, the sand dunes around Maili bog supported a denser vegetation, with Quer-cus mongolica Fisch., Tilia L., Uhnus L. as its dominating taxa. Declination of the open forest and increase of major herb taxa since 3 100 a BP suggest an increasing area of semi-fixed and partly active sand dunes mainly supporting Artemisia L. and Chenopodiaceae. Such a changing process has generally been continued through the last 3 000 years. However, the period from 1 000 a BP to 660 a BP was unique in that it witnessed a lush growth of nearly all of the taxa in the region, with the expanding of Quercus mongolica population being especially obvious. The desertification process starting at 3 100 a BP ceased during that time, and the different types of sand dunes were supporting a much denser vegetation covered in the period than any others.