發(fā)布時(shí)間：2018-03-18 08:13

  本文選題：共和盆地　切入點(diǎn)：表土花粉　出處：《華中師范大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：青海共和盆地位于青藏高原東北部的祁連山與昆侖山之間,處于季風(fēng)影響的邊界區(qū)和氣候的過(guò)度地帶,對(duì)環(huán)境和氣候的變化較為敏感。花粉是研究古環(huán)境和古氣候的重要載體。表土花粉特征分析為沉積物孢粉組合恢復(fù)古植被、古環(huán)境提供重要參考依據(jù)和前提保證。本文通過(guò)對(duì)共和盆地46個(gè)表土樣品的孢粉分析,主要探討了青海共和盆地不同植被類型下表土花粉組合的特征,主要科屬花粉分布特征與植被關(guān)系,花粉的A/C值分析及孢粉組合的PCA分析,初步得出以下結(jié)論：(1)表土樣品花粉的組合特征基本能反映該區(qū)的植被情況,在各個(gè)植被群落中,都是以草本和灌叢花粉占據(jù)絕對(duì)優(yōu)勢(shì),喬木樹(shù)種花粉含量較少。臺(tái)地干草原、荒漠與半荒漠、河漫灘和高山草甸群落中,草本和灌叢花粉以禾本科、莎草科、毛茛科、白刺屬、蒿屬和藜科為主,百分含量都在79.69%以上,而喬木樹(shù)種花粉以松屬、樺木屬、云杉屬為主,百分含量低于19.76%。其中在山前沖積扇中,喬木樹(shù)種花粉百分含量有所增大,最高達(dá)到了37.35%,但仍以草本和灌叢花粉為主。(2)青海共和盆地不同群落類型的46個(gè)表土樣品的花粉組合中都存在著一定數(shù)量的喬木樹(shù)種花粉,主要為云杉、松屬、樺木屬和楊屬。參考本文研究區(qū)域的植被資料顯示,本地并無(wú)喬木森林的生長(zhǎng),因此本文認(rèn)為該區(qū)表土花粉組合中的喬木樹(shù)種花粉可能主要是從外圍地區(qū)經(jīng)過(guò)不同的路徑傳播而來(lái),另外聚落點(diǎn)周圍也有可能受到有人工種植的松樹(shù)花粉的影響。(3)青海共和盆地主要科屬花粉分布特征大體上與植被相對(duì)應(yīng),草本和灌叢花粉的百分含量和絕對(duì)濃度基本上能反映該區(qū)域內(nèi)地表的植被組成與分布狀況,但喬木樹(shù)種花粉的百分含量和絕對(duì)濃度不能準(zhǔn)確反映該研究區(qū)存在森林植被的生長(zhǎng)。(4)青海共和盆地表土花粉的A/C值總體上可以反映該區(qū)的干濕程度,干旱的氣候環(huán)境狀況中藜科花粉在表土花粉組合中占據(jù)優(yōu)勢(shì),而在半干旱的氣候環(huán)境中蒿屬花粉百分含量最高。但在臺(tái)地干草原中蒿屬花粉不占優(yōu)勢(shì),A/C值呈現(xiàn)小于1,甚至比荒漠區(qū)還有低,這可能是受到人類活動(dòng)、過(guò)度放牧等因素的影響,引起草場(chǎng)退化導(dǎo)致。(5)青海共和甕地孢粉組合PCA分析表明,第一個(gè)因子對(duì)代表干旱的藜科和蒿屬植被的生長(zhǎng)有所抑制,主要反映了較濕潤(rùn)的生態(tài)環(huán)境；第二因子有利于抗干旱的喬木植被的生長(zhǎng),而不利于大多的中生草本植被；第三因子中耐旱的白刺屬花粉特征值較高,而一些代表濕潤(rùn)的花粉特征值較低,表明了環(huán)境較為干旱；第四因子中蒿屬植被生長(zhǎng)占有優(yōu)勢(shì),而藜科受到限制,反映了研究區(qū)內(nèi)的環(huán)境濕度狀況,說(shuō)明濕度是影響該地孢粉組合特征的一個(gè)主要因素,可作為一種探討影響氣候的指標(biāo)。共和盆地主要科屬花粉的排序結(jié)果和樣品的排序狀況基本對(duì)應(yīng),利用PCA分析基本上可以將不同生態(tài)環(huán)境的樣品區(qū)分開(kāi)來(lái)。
[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.
【學(xué)位授予單位】：華中師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：Q914

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