發(fā)布時間：2018-05-29 20:34

  本文選題：土壤微生物群落 + 草地�。� 參考：《清華大學》2016年博士論文

【摘要】：草原生態(tài)系統(tǒng)作為陸地生態(tài)系統(tǒng)的最重要類型之一,承擔著多種生態(tài)功能。土壤微生物作為分解者,在維持生態(tài)系統(tǒng)平衡上起著至關重要的作用。隨著全球氣候逐漸變暖,溫度變化對土壤微生物群落的影響無疑也會影響到微生物驅動的生物地球化學循環(huán)。然而由于土壤微生物的復雜性,以及研究方法的限制,目前我們對于土壤微生物如何響應氣候變暖的了解還非常有限。本研究以中國青藏高寒草原、中國內(nèi)蒙古半干旱草原及美國加州半干旱草原為研究對象,利用宏基因組學技術中的高通量測序技術和基因芯片(GeoChip)技術,從土壤微生物群落的物種組成和功能結構角度深入探究微生物對增溫的響應機制,本研究發(fā)現(xiàn):(1)對三個草原生態(tài)系統(tǒng)增溫試驗的土壤微生物群落結構分析表明功能基因對增溫響應比物種敏感。(2)土壤微生物群落物種組成在不同的增溫條件下對增溫有不同的響應策略。在內(nèi)蒙古半干旱草原中(1℃,6年),微生物物種組成沒有明顯的變化。而在美國加州半干旱草原中(1—1.5℃,14年),生長快的富營養(yǎng)菌,如擬桿菌(Bacteroides)物種豐度降低,生長慢的寡營養(yǎng)菌,如酸桿菌(Acidobacteria)物種豐度升高。(3)土壤微生物功能基因在不同的增溫條件下對增溫有不同響應策略。在高寒草原中,碳固定基因豐度,氨化和反硝化基因豐度都在增溫后降低,硝化基因豐度在增溫后升高。且N2O排放量與硝化基因amoA豐度顯著正相關,與反硝化基因nirS和norZ成負相關,該生態(tài)系統(tǒng)硝化作用是N2O排放的主導過程。在內(nèi)蒙古半干旱草原中,光能固碳途徑3HP和卡爾文循環(huán)基因豐度,氨化及反硝化基因豐度在白天增溫下升高,夜間增溫和全天增溫下功能基因豐度沒有顯著變化。而在美國加州半干旱草原中,厭氧碳固定途徑基因豐度在增溫下升高,碳降解中易降解碳基因豐度升高而難降解碳基因豐度降低。此外,反硝化基因豐度降低。(4)功能基因和物種對增溫響應不同原因是兩者受不同環(huán)境因子影響。微生物物種組成主要受植被等因子影響,而功能基因結構主要受土壤營養(yǎng)影響。本研究全面分析了草原生態(tài)系統(tǒng)土壤微生物物種組成和功能結構對增溫的響應,對于有效管理生態(tài)系統(tǒng),減少未來氣候變化所帶來的不利影響有重要意義。
[Abstract]:Grassland ecosystem, as one of the most important types of terrestrial ecosystem, bears a variety of ecological functions. Soil microorganisms, as decomposers, play a vital role in maintaining ecosystem balance. With the global climate warming, the effect of temperature on soil microbial community will undoubtedly affect the biogeochemical cycle driven by microbes. However, due to the complexity of soil microbes and the limitations of research methods, our understanding of how soil microbes respond to global warming is very limited. In this study, the semi-arid steppe of Qinghai-Tibet, Inner Mongolia and California were used as the research objects, and the high-throughput sequencing technique and the gene chip GeoChip technique were used in macrogenomics. From the point of view of species composition and functional structure of soil microbial community, the response mechanism of microorganism to temperature was studied. In this study, we found that the soil microbial community structure of three steppe ecosystem temperature-increasing experiments showed that the functional genes were more sensitive to the temperature response than the species. 2) the species composition of the soil microbial community was increased under different temperature conditions. Temperature has different response strategies. In Inner Mongolia semi-arid steppe, there was no obvious change in microbial species composition at 1 鈩，

本文編號：1952300