土壤增温对中亚热带杉木幼林土壤微生物群落结构和有效氮的影响

Effects of Soil Warming on Soil Microbial Community Structure and Soil Available Nitrogen in Subtropical Young Chinese fir Plantation

以中亚热带杉木(Cunninghamia lanceolata)幼苗为研究对象,设置埋设电缆以加热土壤增温(+5℃)的实验,研究了土壤理化性质、土壤有效氮和土壤微生物群落结构等对模拟全球变暖的短期响应。结果表明:1)增温1年后土壤硝态氮含量显著提高1.6倍;p H值、土壤有机碳、总氮和有效磷略有降低,但差异未达显著水平;土壤水分在增温之后明显减少。2)增温导致革兰氏阳性细菌(Gram-positive bacteria,G+)、革兰氏阴性细菌(Gram-positive bacteria,G-)、真菌(Fungi)、放线菌(ACT)和丛枝菌根真菌(AMF)的磷脂脂肪酸(PLFA)生物量均显著减少,G+∶G-在增温之后显著提高,而真菌与细菌比(F∶B)显著降低。3)冗余分析(RDA)显示,温度(T)、土壤含水量(SMC)和硝态氮是决定土壤微生物群落结构变化最重要的环境因子。研究表明,短期增温促进了土壤有机氮矿化,改变了微生物群落结构,细菌中G+相对于G-优势明显。中亚热带杉木人工林土壤有效氮和微生物群落对模拟全球变暖的反应敏感,但长期实验后二者如何变化仍未可知。因此,该区域在未来全球变暖背景下微生物群落和土壤有效养分的响应值得长期而深入的探讨。

Global warming have been causing a series of environmental problems, which attracts much attention of research workers, government agencies and the international society. With setting the un- derground cables to warming, we aim to study the responses of the soil microbial community structure and soil available nitrogen to the short-term simulated warming in young Chinese fir （Cunninghamia lanceolata） in Sanming, Fujian province in subtropical China. The results showed that： 1 ） the short- term warming didn＇t significantly change soil organic carbon, total nitrogen and available phosphorus. 2） PLFA biomass of G ＋, G - , Fungi, ACT, AMF, and G ＋ ： G - significantly decreased by soilwarming, while the ratio of F： B decreased significantly. 3 ） The results of Redundancy analysis （RDA） showed that T, SMC, and nitrate nitrogen were the most important environmental factors deter- mining the change of soil microbial community structure. The study indicated that the short-term war- ming promoted the mineralization of soil organic nitrogen, changed the microbial community structure, and G ＋ became the dominant community. Soil available nitrogen and microbial communities of Chi- nese Fir Plantation in subtropical China are sensitive to the response of global warming, but the change of that in the long term is not known. Therefore, the change of microbial communities and soil availa- ble nutrients under the background of global warming in the future is worth a long and deep study, in order to reveal the response and feedback mechanism of Chinese fir plantation to global climate change in subtropical China.