高寒草甸土壤微生物功能多样性对积雪变化的响应

积雪是高寒地区不可忽视的生态因子，不仅直接影响土壤温度、水分，而且间接影响土壤微生物群落组成和多样性。为研究高寒草甸生态系统中土壤微生物对积雪变化的响应，于2013年11月至2014年7月在青藏高原东缘红原县高寒草甸，通过人工堆积的方法建立4个不同积雪梯度，以自然积雪量为对照（CK），2倍于自然积雪量（S1）、3倍于自然积雪量（S2）、4倍于自然积雪量（S3）。运用Biolog-Eco板法研究不同积雪梯度下土壤微生物功能多样性，并测定积雪变化对土壤温度和土壤养分的影响。结果表明：积雪期内，0~10 cm土层土壤温度随着积雪量的增加而降低，而10~20 cm土层随积雪量增加先降低后升高。增加积雪量处理后0~10 cm土层全磷（TP）、有机碳（SOC）显著增加（P<0.05）；而10~20 cm土层仅S3下全氮（TN）、TP、SOC增加。每孔平均变化率值（Average well color development，AWCD）在0~10 cm土层表现为CK > S2 > S1 > S3，而10~20 cm表现为S2 > S1 > CK > S3。在0~10 cm土层，S3处理显著降低了土壤微生物多样性McIntosh指数、Shannon-Wiener指数和Pielou指数（P<0.05）； 10~20 cm土层，S1和S2处理下多样性指数显著增加（P<0.05）。主成分分析显示：氨基酸类和酚酸类是微生物利用的主要碳源类型。相关性分析表明：多样性指数与TP、SOC、碳氮比（C/N）显著负相关（P<0.05），氨基酸类碳源与TP、C/N显著负相关（P<0.05）。因此，冬季积雪一定程度上影响着土壤温度和土壤养分，进而影响高寒草甸土壤微生物群落功能多样性。

Response of soil microbial function diversity to snow cover gradient in alpine meadow soil of Qinghai-Tibet Plateau

Snow is an important normal environment factor in the alpine meadow ecosystem, which not only directly affects the soil temperature and moisture, but also affects the soil microbial community composition and diversity. Therefore, it is necessary to determine how snow depth affects the soil microbial community in the alpine meadow ecosystem. We used four treatment of snow cover gradients (S1 2 times, S2 3 times, S3 4 times) and natural snow cover, which was the control (CK). Soil microbial function diversity was studied by Biolog-Eco microplate. Besides, soil temperature was measured under different snow cover gradients. The result showed that temperature decreased with depth within 0~10 cm depth range, whereas temperature firstly increased and then decreased with depth within 10~20 cm depth range. Total phosphorus (TP) and organic carbon (SOC) increased significantly in the 0~10 cm depth range for S1, S2 and S3, but only in S3 increased significantly in the 10~20 cm soil depth range. Average well color development (AWCD), Shannon-Wiener index, Pielou index and McIntosh index decreased in the 0~10 cm depth range as CK > S2 > S1 > S3, and in the 10~20 cm depth range as S2 > S1 > CK > S3. The principal component analysis (PCA) showed that amino acids and phenolic acids were mainly carbon sources for carbon source utilization of the soil microbial community. Correlations analysis showed that soil nutrients with functional diversity indexes and carbon sources, there was significant negative correlation between microbial functional diversity index and TP, SOC, C/N. But amino acids was significant negative correlation with TP and C/N. It is believe that the snow in winter impacts soil temperature and soil nutrient contents, and then changes soil microbial functional diversity in alpine meadow ecosystem.