[Ecological distribution patterns of soil microbes under artificial Eucalyptus grandis stand]

In order to find out the ecological distribution patterns of soil microbes under artificial Eucalyptus grandis stand, the amount and distribution of soil bacteria, fungi and actinomycetes in Hongya County of Sichuan Province were investigated in 2004. The results showed that soil microbial population under Eucalyptus grandis stand varied with seasons, being the maximum in autumn, fewer in spring, and the minimum in summer. The numbers were decreased in order of bacteria > actinomycetes > fungi, which were mainly concentrated in 0-20 cm soil layer, and rapidly decreased with increasing soil depth. In 0-60 cm soil layer, the numbers of aerobic bacteria were 0. 31 x 10(6) - 14.39 x 10(6), actinomycetes were 0.06 x 10(6) - 0.79 x 10(6), fungi were 0.06 x 10(6) - 0.79 x 10(6), and anaerobes were 0.05 x 10(6) - 3.22 x 10(6) CFU x g(-1). Comparing with artificial C. glauca stand and farming land, Eucalyptus grandis stand had a larger number of soil microbes, suggesting that Eucalyptus grandis was benefit for soil microbial activity. The Simpson and Shannon-Wiener index of the physiological groups of bacteria was 0.773 and 1.896, respectively.