8.0 ka B.P.以来三江平原北部沼泽发育和古环境演变研究

8.0 ka B.P.以来,三江平原北部气候变化序列划分为5个阶段,温暖湿润(8000~5590 a B.P.)→较温暖湿润(5590~1851 a B.P.)→温冷稍湿(1851~1110 a B.P.)→寒冷偏湿(1110~649 a B.P.)→冷凉略湿(649 a B.P.~至今)。气候的变化模式依次为:高温期→温暖适宜期→缓慢降温期→急剧降温期→低温渐暖期。在5590 a B.P.和1317 a B.P.,发生强烈降温事件。沼泽发育也依次划分为5个时期,沼泽化过程发展期→沼泽大发展期→沼泽发育缓慢期→沼泽发育波动期→沼泽发育萎缩期。植被演替相应为:温性阔叶林→针、阔叶混交林和草原→以落叶阔叶树稍多的针、阔叶混交林和草原→以桦为主的阔叶林→针阔混交林、以松占优势的针、阔叶混交林和草原。在1851~1317 a B.P.、649~309 a B.P.和309~0 a B.P.期间,受频繁的农业生产、砍伐森林、开垦沼泽为农田等人类活动的影响,沼泽发育呈现退化的趋势。

Study on Mire Development and Paleoenvironment Change since 8.0 ka B.P. in the Northern Part of the Sangjiang Plain

The paper makes relative high-resolution approach on the relationship among mire development, paleoenvironment change and human activity since 8.0 ka B.P. in the northern part of the Sanjiang plain. The model of the climate change can be reconstructed as high temperature period at 8000-5590 a B.P., warm period at 5590-1851 a B.P., slowly dropping period in temperature at 1851-1110 a B.P.,rapidly dropping period in temperature at 1110-649 a B.P., dropping in temperature and then warming period at 649-0 a B.P. The vegetation succession can be divided into five stages in proper corresponding period above-mentioned, i.e. temperate deciduous broad-leaved foreste, needle-broad-leaved mixed forest and grassland, needle-broad-leaved mixed forest dominated by deciduous broad-leaved trees and grassland, broad-leaved forest dominated by Betula , needle-broad-leaved mixed forest and needle-broad-leaved mixed forest dominated by Pinus and grassland. The close relationship was found between mire development and paleoenvironment change in the five periods in proper corresponding period above-mentioned in the given order, i.e .the breeding and germinating development of paludification process period, the vigorous development period, slow development and shriveling period, fluctuation period, shriveling period. On the whole, the mire has been in the stage of eutrophic mire stage. Although the environment changed frequently since 8.0 k a B.P., it was still favorable to the formation and development of eutrophic mire. The mire development and paleoenvironment change were mainly driven by nature environment factor, but the human activities gave a strong influence on them too. In 1851-1317a B.P., 649-309 a B.P. and 309 a B.P.-0, the mire was degraded by the human activities, i.e. agricultural production, deforestation and mire exploitation. The mire-profile of 30th team, Qindeli farm can be considered as the standard profile since 8.0 ka B.P. in this region.