摘要
DJ孔中含有丰富的花粉 .剖面中花粉沉积率最高可达 2 0 0 0 0粒· cm- 2 · a- 1以上 .最低仅为 80～ 90粒·cm- 2 · a- 1.从花粉组合中可以发现 ,乔木花粉含量相当丰富 ,尤其在 90 0 0～ 2 5 0 0 a BP更是如此 ,乔木花粉最高可达 80 %以上 ,一般都多于 5 0 %.乔木主要种类为松属 Pinus 、桦属 Betula 、云杉属 Picea 、冷杉属 Abies 、鹅耳枥属 Carpinus 、栎属 Quercus 、榆属 Ulmus 等十几种类型 .草本和灌木花粉以蒿属 Artemisia 最为丰富 ,最多可达 80 %以上 ,其次为麻黄属 Ephedra 、藜科 ,此外还包括菊科、禾本科、豆科、唇形科、白刺属 N itraria 、蓼科、毛莨属、唐松草属 Thalictrum 、伞形花科、石竹科、莎草科等共 2 7个科属的花粉 .同时发现蕨类孢子、水生植物花粉和藻类植物 .根据花粉在钻孔上的变化 ,结合花粉沉积率进行样品的有序聚类分析 ,自下而上将 DJ孔分为 5个花粉组合带 .约 630 0 a BP和 5 1 0 0a BP前后 ,出现两个花粉沉积率的高峰值 ,630 0 a BP反映相对温湿时段 .与此相反 ,5 1 0 0 a BP则反映一个相对温干的时段 .通过对 DJ孔化石花粉高分辨分析和现代表土花粉资料的研究表明 ,内蒙古中部气候和植被变化不仅存在千年、百年尺度的波动 ,同时存在更短时间尺度。
Pollen analysis resulted from 111 core samples from Diaojiao (DJ) Lake Inner Mongolia have shown the highest value of total pollen accumulation rate was more than 20000 grains·cm -2 ·a -1 and lowest was 80～90 grains·cm -2 ·a - 1 . In general, the arboreal pollen was more than 50%, up to 80%, including the following families and genera: Pinus, Betula, Picea, Carpinus, Quercus, Ulmus etc. The non arboreal pollen consist of 27 types, which mainly include Artemisia, Ephedra, Chenopodiaceae, Compositae,Gramineae, Leguminosae, Labiatae, Nitraria, Polygonaceae, Ranunculus, Thalictrum, Umbelliferae, Caryophyllaceae and Cyperaceae etc. Fern spores, aquatic pollen and algae were also observed off and on in the DJ core. A pollen diagram, of five pollen assemblage zones was established through stratigraphically constrained cluster analysis using the method of incremental sum of squares. It shows two peaks appearing at about 6.3 and 5.1 ka BP in the curve of total pollen accumulation rate. The first peak reflects a humid period and the second an arid period. The study indicated that Holocene climatic and vegetational changes in Inner Mongolia can be recongnized at different time scales(e.g. thousands, hundreds of years, or even much shorter time scale).In addition, the humidity in that area during those time was higher than today, with dominent climate humid cool or humid warm during most of the Holocene time on account of the lower vaporization and high altitude (1800 m a.s.l.).
基金
国家自然科学基金
关键词
古植物生态学
大青山
全新世
古植被
Daqingshan Mountain
Holocene
Paleovegetational changes
