SUN Hongzhe, MA Dalong, ZANG Shuying, WU Xiangwen
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.
