干旱区典型盐生植物群落下土壤微生物群落特征

运用Biolog技术,对干旱区玛纳斯河流域扇缘带的6种典型盐生植物群落下土壤微生物群落特征差异性进行了研究,探讨不同植物群落对土壤微生物群落的影响。结果表明:不同盐生植物群落土壤平均颜色变化率(AWCD)随培养时间的延长而逐渐增加,大小顺序依次为:梭梭花花柴白刺绢蒿柽柳雾冰藜,且差异显著。不同植物群落土壤微生物对6类碳源利用差异显著(P0.05),其中梭梭群落利用率最高,雾冰藜群落利用率最低。碳水化合物类和氨基酸类是主要碳源,胺类的利用率最低。主成分分析(PCA)表明,在31种因子中提取的2个主成分因子,分别可以解释所有变量方差的41.51%和25.35%,对PC1和PC2起分异作用的主要碳源分别为碳水化合物类和氨基酸类。土壤微生物群落Shannon指数、Simpson指数上,除雾冰藜群落较低,其他群落之间均差异不显著(P0.05)。植物群落Margalef指数,Shannon指数和Simpson指数上,均为绢蒿,梭梭和柽柳群落较为优势。相关性分析表明,植物群落多样性指数与土壤微生物多样性指数呈显著正相关关系(P0.05),说明了植物多样性越丰富,土壤微生物越丰富。总体来说,干旱区不同盐生植物群落对土壤微生物群落多样性具有重要影响。其中,梭梭群落的土壤微生物群落具有较强的微生物总体活性和功能多样性。

Soil microbial properties under typical halophytic vegetation communities in arid regions

Soil microbes play a key role in material recycling and energy conversion in arid areas. Currently, research on soil microbial community diversity mainly focuses on environmental change and human disturbance, and not on natural ecosystems. In Xinjiang, a variety of halophytes develop in arid areas, and play an active role in the balance of desert oases ecosystems, but there are relatively few studies on soil microbial community diversity in different halophyte communities. The difference between soil microbial diversity and carbon source utilization under different halophyte communities needs to be elucidated. Therefore, a field experiment was conducted to quantify changes in the functional diversity of the soil microbial community under six halophyte communities (Nitraria tangutorum, Seriphidium kaschgaricum, Karelinia caspia, Bassia dasyphylla, Tamarix ramosissima, and Haloxylon ammodendron) using Biolog analysis in the alluvial fan area of the Manas River watershed. The objective of the present study was to determine 1) the effects of different halophyte communities on carbon source utilization, 2) which halophyte community has stronger activity and microbial functional diversity and 3) the relationship of the ground vegetation diversity and soil microbial community diversity. The results revealed that the average well color development (AWCD) increased with increasing incubation time, and there were significant differences among different vegetation communities, in order of H. ammodendron > K. caspia > N. tangutorum > S. kaschgaricum > T. ramosissima > B. dasyphylla (P < 0.05). There were significant differences among substrates used by soil microbial communities in different halophyte communities (P < 0.05). The substrate used in H. ammodendron was the highest, and that in B. dasyphylla was the lowest. The carbon sources most used by soil microbes were carbohydrates and amino acids, followed by phenolic acids, polymers and carboxylic acids, and the lowest was amines. Principal component analysis (PCA) identified two factors related to carbon sources explaining 4.51% and 25.35% of the variation. Carbohydrates and amino acids were the two main carbon sources separating the two principal component factors. The Shannon and Simpson indices of soil microbial communities in B. dasyphylla were significantly lower than in other communities (P < 0.05), the Pielou index of soil microbial community in N. tangutorum was significantly higher than in other communities (P < 0.05), and there were no significant differences between other communities (P > 0.05). The Margalef, Shannon, and Simpson indices of vegetation communities in S. kaschgaricum, H. ammodendron, and T. ramosissima were more dominant. There were significantly positive correlations between the indices of vegetation richness, diversity, dominance, and soil microbial diversity and dominance (P < 0.05), showing that richer vegetation diversity was related to richer soil microbial diversity. Overall, different halophytic communities have important effects on soil microbial communities in arid areas. The soil microbial community of H. ammodendron has the highest microbial activity and functional diversity.