增温和增氮对荒漠草原土壤可培养真菌群落结构和多样性的影响

为了探讨气候变化对荒漠草原土壤真菌群落结构和多样性的影响,进而更有效地管理草原,在内蒙古短花针茅(Stipa breviflora)荒漠草原进行远红外线辐射器模拟增温和人工施肥模拟增氮试验。经过6年的连续模拟试验后,采用稀释平板涂布法结合18SrRNA分子鉴定技术,对试验地土壤可培养真菌群落的组成和多样性进行分析。结果表明,1)从内蒙古短花针茅荒漠草原土壤中共分离获得17个属的可培养真菌;2)模拟增氮不增温、增温增氮处理均使可培养真菌的菌落数显著增加(P0.05),分别由不增氮不增温的菌落数6.70×105 CFU·g~(-1)升高到1.45×106和1.92×106 CFU·g~(-1),但二者间差异不显著(P0.05);3)增氮不增温、增温增氮处理的群落组成和优势属发生了改变,在增氮不增温处理中的优势菌属为镰刀菌属(Fusarium)、交链孢霉属(Alternaria)和假裸囊菌属(Pseudogymnoascus);增温增氮处理的优势菌属为青霉属(Penicillium)和曲霉属(Aspergillus)、镰刀菌属、交链孢霉属和Chromocleista;4)与其它两个处理相比,增氮不增温处理显著提高了荒漠草原可培养真菌的物种丰富度、均匀度和多样性。增温增氮对群落内物种丰富度、均匀度和多样性均没有显著影响。

Effect of warming and nitrogen addition on the community composition and diversity of cultivatable fungi from the desert steppe of Inner Mongolia

To understand how to effectively manage a desert steppe environment during a period of warming and nitrogen deposition, the effects of nitrogen (N) addition and warming on the community structure and diversity of cultivatable fungi were studied.The dilution plate method was used together with the molecular analysis of 18S rRNA after the application of infrared radiation to simulate global warming and fungi were artificially fertilised for 6 years in a desert steppe with the dominant species of Stipa breviflora in Inner Mongolia.The results indicated that 17 fungal genera were isolated from the desert soil.N addition alone or with simulated warming led to a significant (P<0.05) increase in the total number of cultivatable fungi from 6.70×105 colony-forming units·g-1 in the untreated control to 1.45×106 or 1.92×106 colony-forming units·g-1, respectively.Moreover, the community composition and dominant species changed with N addition.With N addition alone, the dominant fungal genera Aspergillus, Hypocrea, and Cladosporium were replaced by Fusarium, Alternaria, and Pseudogymnoascus, and the species richness, evenness, and diversity significantly increased.The effect of N addition with simulated warming increased the abundance of the dominant fungal genera Penicillium and Aspergillus, and another three dominant fungal genera were replaced by Fusarium, Alternaria, and Chromocleista.Combining N addition with simulated warming had no significant effects on the species richness, evenness, and diversity of cultivable fungi, compared with N addition alone.