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本文依据北京坟庄晚更新世、早全新世孢粉图式,提出北京地区距今30000年时,曾经在丘陵和平原地区繁盛过以云杉、冷杉为优势的针叶林,在22000年左右,进入以蒿、藜和禾本科为代表的草原阶段。在距今13000—12000年,以云杉、冷杉、落叶松为代表的亚高山针叶林又一次扩展到北京丘陵和平原地区。当时湖沼发育,气候冷湿,泥炭累积。由于在12000年时暖温带落叶阔叶林分布区扩展,标志着当时气候回升,故提出更新世和全新世的界限应为12000年左右为宜。
Based on the late Pleistocene and Early Holocene sporo-pollen patterns in Fenzhuang, Beijing, this paper presents the coniferous forests of spruce and fir that had flourished in the hills and plains in the past 30000 years in Beijing. In the period of about 22000 , Into the steppe stage represented by Artemisia, quinoa and grass. From 13000 to 12000 years ago, the sub-alpine coniferous forest, represented by spruce, fir and larch, once again extends to the hilly and plains areas of Beijing. At that time lake development, cold and humid climate, peat accumulation. Due to the expansion of the warm temperate deciduous broad-leaved forest at 12000 years, which marked the climax of the climate at that time, the limit of Pleistocene and Holocene should be about 12000 years.