Distribution of soil microorganism in Larix gmelinii forests of the Great Xing’an Mountains，Inner Mongolia

The soil microbial distribution of bacteria，fungi，and actinomycetes in five different Larix gmelinii forests［（A） Ledum palustre-Larix gmelinii virgin forest，（B） herbage-Larix gmelinii virgin forest，（C） Betula fruticosa-Larix gmelinii virgin forest，（D） Larix gmelinii forest burned-over areas，and （E） clearcut Larix gmelinii forest］ in 0 － 10，10 － 20，20 － 30 cm soil layers was studied in the National Forestry Ecosystems Station of Inner Mongolias Great Xingan Mountains using the dilution-plate method. Results showed that in the different forest types，soil microbes varied in quantity，category，and vertical distribution（P＜0.05）. Also，bacteria were dominant accounting for 80.2% － 96.8% of the microorganisms. Numbers of all microorganisms in the Larix gmelinii forests were in the order：A＞B＞C＞D＞E；whereas bacteria were A＞B＞C＞D＞E，fungi were E＞C＞A＞B＞D，and actinomycetes were A＞B＞D＞E＞ C. In virgin forests actinomycetes in the 10 － 20 cm layer were greater than the 0 － 10 cm layer；but vertical distribution of bacteria and fungi decreased（P＜0.05） with the increasing vertical depth.［Ch，4 fig. 1 tab. 15 ref.］