青海共和盆地表土花粉研究

发布时间：2018-03-18 08:13

本文选题：共和盆地　切入点：表土花粉　出处：《华中师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：青海共和盆地位于青藏高原东北部的祁连山与昆仑山之间,处于季风影响的边界区和气候的过度地带,对环境和气候的变化较为敏感。花粉是研究古环境和古气候的重要载体。表土花粉特征分析为沉积物孢粉组合恢复古植被、古环境提供重要参考依据和前提保证。本文通过对共和盆地46个表土样品的孢粉分析,主要探讨了青海共和盆地不同植被类型下表土花粉组合的特征,主要科属花粉分布特征与植被关系,花粉的A/C值分析及孢粉组合的PCA分析,初步得出以下结论：(1)表土样品花粉的组合特征基本能反映该区的植被情况,在各个植被群落中,都是以草本和灌丛花粉占据绝对优势,乔木树种花粉含量较少。台地干草原、荒漠与半荒漠、河漫滩和高山草甸群落中,草本和灌丛花粉以禾本科、莎草科、毛茛科、白刺属、蒿属和藜科为主,百分含量都在79.69%以上,而乔木树种花粉以松属、桦木属、云杉属为主,百分含量低于19.76%。其中在山前冲积扇中,乔木树种花粉百分含量有所增大,最高达到了37.35%,但仍以草本和灌丛花粉为主。(2)青海共和盆地不同群落类型的46个表土样品的花粉组合中都存在着一定数量的乔木树种花粉,主要为云杉、松属、桦木属和杨属。参考本文研究区域的植被资料显示,本地并无乔木森林的生长,因此本文认为该区表土花粉组合中的乔木树种花粉可能主要是从外围地区经过不同的路径传播而来,另外聚落点周围也有可能受到有人工种植的松树花粉的影响。(3)青海共和盆地主要科属花粉分布特征大体上与植被相对应,草本和灌丛花粉的百分含量和绝对浓度基本上能反映该区域内地表的植被组成与分布状况,但乔木树种花粉的百分含量和绝对浓度不能准确反映该研究区存在森林植被的生长。(4)青海共和盆地表土花粉的A/C值总体上可以反映该区的干湿程度,干旱的气候环境状况中藜科花粉在表土花粉组合中占据优势,而在半干旱的气候环境中蒿属花粉百分含量最高。但在台地干草原中蒿属花粉不占优势,A/C值呈现小于1,甚至比荒漠区还有低,这可能是受到人类活动、过度放牧等因素的影响,引起草场退化导致。(5)青海共和瓮地孢粉组合PCA分析表明,第一个因子对代表干旱的藜科和蒿属植被的生长有所抑制,主要反映了较湿润的生态环境；第二因子有利于抗干旱的乔木植被的生长,而不利于大多的中生草本植被；第三因子中耐旱的白刺属花粉特征值较高,而一些代表湿润的花粉特征值较低,表明了环境较为干旱；第四因子中蒿属植被生长占有优势,而藜科受到限制,反映了研究区内的环境湿度状况,说明湿度是影响该地孢粉组合特征的一个主要因素,可作为一种探讨影响气候的指标。共和盆地主要科属花粉的排序结果和样品的排序状况基本对应,利用PCA分析基本上可以将不同生态环境的样品区分开来。
[Abstract]:The Gonghe Basin in Qinghai lies between the Qilian Mountains and the Kunlun Mountains in the northeast of the Qinghai-Xizang Plateau. Pollen is an important carrier to study paleoclimate and paleoclimate. The paleoenvironment provides an important reference and premise guarantee. Based on the pollen analysis of 46 topsoil samples in Gonghe Basin, this paper mainly discusses the characteristics of pollen assemblage of topsoil under different vegetation types in Gonghe Basin, Qinghai Province. The relationship between pollen distribution and vegetation, the A- / C value of pollen and the PCA analysis of pollen assemblage were analyzed. It was concluded that the pollen combination characteristics of topsoil samples could basically reflect the vegetation in this area. They are dominated by herbaceous and shrubby pollen, and the pollen content of Arbor species is relatively small. In the steppe, desert and semi-desert, floodplain and alpine meadow communities, herbaceous and shrubby pollen are gramineous, Cyperidae, Ranunculaceae, Spurs. In Artemisia and Chenopodiaceae, the percentage of pollen is more than 79.69%, while the pollen content of Arbor species is mainly pine, birch and spruce, and the percentage of pollen is less than 19.76B. among them, the pollen content of Arbor species increases in front of mountain alluvial fan. The pollen combinations of 46 topsoil samples of different community types in the Gonghe Basin of Qinghai Province have a certain amount of pollen from Arbor species, mainly spruce, pine, etc. According to the vegetation data of this study area, there is no growth of Arbor forest. Therefore, this paper thinks that the pollen of Arbor species in the pollen assemblage of the topsoil in this area may be mainly transmitted from the peripheral areas through different paths. In addition, the pollen distribution characteristics of the main genera and families in the Gonghe Basin, Qinghai Province, may also be affected by the pollen of the pine trees planted artificially. The distribution characteristics of pollen in the main genera and families in the Gonghe Basin, Qinghai Province, are generally corresponding to the vegetation. The percentage content and absolute concentration of herbaceous and shrub pollen can basically reflect the vegetation composition and distribution in the surface of the region. However, the percentage content and absolute concentration of pollen of Arbor species can not accurately reflect the growth of forest vegetation in this study area.) the A / C value of pollen of surface soil in Gonghe Basin of Qinghai Province can reflect the degree of dryness and wetness in this area as a whole. Chenopodiaceae pollen is dominant in topsoil pollen combinations in arid climate and environment. In semi-arid climate environment, artemisia pollen content is the highest, but in the terrace steppe, the A / C value of Artemisia pollen is less than 1, even lower than that in desert area. This may be affected by human activities, overgrazing and other factors. The PCA analysis of sporopollen assemblage showed that the first factor inhibited the growth of Chenopodiaceae and Artemisia vegetation, which represented drought, and mainly reflected the wetter ecological environment. The second factor is favorable to the growth of drought-resistant Arbor vegetation, but not to most of the mesophytic herbaceous vegetation. The results indicated that the environment was relatively arid, the growth of Artemisia vegetation was dominant in factor 4th, but the Chenopodiaceae was restricted, which reflected the environmental humidity in the study area, indicating that humidity was a major factor affecting the sporopollen assemblage in this area. The results of pollen sequencing of the main families and genera in Gonghe Basin are basically corresponding to the order status of samples, and the samples from different ecological environments can be basically distinguished by PCA analysis.
【学位授予单位】：华中师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：Q914

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