大兴安岭多年冻土区不同林型土壤微生物群落特征

高纬度多年冻土区是全球变化的敏感区域，揭示不同林型土壤微生物群落的演变规律，对于理解气候变化对寒区生态系统的影响机制具有重要意义。以大兴安岭多年冻土区3种典型林型（落叶松林、樟子松林和白桦林）为研究对象，运用磷脂脂肪酸法（PLFA）系统研究土壤微生物群落结构间差异及与土壤因子的关系。结果表明：不同林型土壤中共检测到38种PLFA生物标记，含量较高的PLFA为16∶0、18∶0、19∶0和18∶2ω6c；各类群微生物中，细菌PLFA含量最高，占总磷脂脂肪酸的83.78%~90.55%，其次为真菌，放线菌最低；白桦林土壤总磷脂脂肪酸、革兰氏阴性菌、革兰氏阳性菌、真菌和放线菌的含量最高分别为22.03、5.13、4.90、1.88和0.77 nmol·g^-1，而樟子松林最低分别为14.25、2.75、2.75、1.34和0.51 nmol·g^-1。Shannon-Wiener多样性指数主要表现为白桦林 > 落叶松林 > 樟子松林。冗余分析结果为：土壤含水量、全氮、总有机碳与总磷脂脂肪酸、细菌、革兰氏阳性菌和革兰氏阴性菌呈显著正相关（P<0.05）；铵态氮、硝态氮、全磷与真菌和放线菌呈显著正相关（P<0.05）。大兴安岭多年冻土区不同林型间土壤微生物群落特征存在显著差异，土壤含水量、全氮和总有机碳是影响多年冻土微生物群落结构的主要因素。

Characteristics of soil microbial community structure under different forest types of permafrost regions in the Greater Khingan Mountains

High-latitude permafrost regions are sensitive to global change. To reveal the evolution law of soil microbial community of different forest types has great significance for understanding the mechanisms of climatic change impacting the ecosystem in cold regions. Taking the three typical forest types (Larix gmelinii, Pinus sylvestris var. mongolica and Betula platyphlla) in permafrost regions of the Greater Khingan Mountains as object, phospholipid fatty acid (PLFA) analysis was applied to examine the difference among soil microbial community structures and the relationship with soil factors. The results showed that there are 38 PLFAs significant in soil of different forest types, of which the highest PLFAs are 16:0, 18:0, 19:0 and 18:2ω6c; among all kinds of microorganism the bacteria PLFA contents are the maximum, accounting for 83.78%-90.55% of total PLFA, followed by fungus, and the actinomycete PLFA contents are the minimum; the maximum contents of total PLFAs, gram-negative bacteria, gram-positive bacteria, fungus and actinomycetes in the Betula platyphllal are 22.03, 5.13, 4.90, 1.88 and 0.77 nmol·g^-1, and the minimum contents of those in Pinus sylvestris var. mongolica are 14.25, 2.75, 2.75, 1.34 and 0.51 nmol·g^-1. The Shannon-Wiener diversity index ranks as Betula platyphlla > Larix gmelinii > Pinus sylvestris var. mongolica. The redundancy analysis shows that the soil water content, total nitrogen, total organic carbon have significantly positive correlation with total PLFAs, bacteria, gram-positive bacteria and gram-negative bacteria in the soil (P<0.05); and ammoniacal nitrogen, nitrate nitrogen, total phosphorus have significantly positive correlation with actinomycetes and fungus (P<0.05). It is revealed that there are significant differences in the characteristics of soil microbial community in the permafrost regions of the Greater Khingan Mountains, and soil water content, total nitrogen, total organic compounds are the basic factors influencing the community structures of microorganism in permafrost soil.