Study About Soil Microbial Edge Effect In Larix Gmelini And Betula Platyphylla Plantation

The larch and birch forest soil of Harbin Experimental Forest Farm as the research objects in order to study the edge effect of soil microorganism.The determination of soil microbial quantity by pour plate method,the determination of soil microbial biomass carbon in the forest by Chloroform fumigation method,the determination of volume weight and porosity of soil by cutting ring method,the determination of total N by semi micro Kjeldahl method,the determination of total K by flame photometry method,the determination of total P by sodium hydroxide-molybdenum antimony colorimetric method,the determination of soil PH value by water leaching potential method,the conventional biochemical identification determination was employed to detect the species of three groups of soil microorganism in birch forest,analysed the vertical distribution of microbial quantity,biomass carbon,diversity index,and the vertical distribution relationship between soil microorganism quantity,biomass carbon,diversity index and physicochemical characteristics.Here are the results:? The quantity of total soil microorganism,fungi,bacteria,actinomycetes,biomass carbon in the Larch and birch forest was exponentially decreased with increasing soil depth.the diversity was decreased with soil depth increasing during the range of 0~50cm.,45 strains of bacteria,38 strains of Actinomycetes,27 strains of fungi were isolated from the birch plantation.With the soil depth increasing,the quantity of all kinds of microorganism had a declining trend.There is an obvious vertical distribution characteristic.? The quantity of soil microorganism in larch plantation forest was effected by total carbon,total Nitrogen,total kaliu,volume weight and porosity,and the same factors also effected soil microbial biomass carbon,diversity index was effected by total carbon,volume weight and porosity mainly in June and October.Soil microbial quantity and biomass carbon of birch forest was effected by total carbon,total kaliu,volume weight and porosity.Diversity index was effected by total carbon,volume weight and porosity in the birch forest.? There is a significant vertical distribution characteristic in soil microbial quantity,biomass carbon and diversity index with the soil depth changed.It's a declining trend with increasing soil depth,or named an obvious edge effect.The lower limit of the ecotone can be obtained by integration and it can be effected by soil physicochemical characteristic.But total carbon,volume weight and porosity are more important factors for the edge effect.Total carbon is the basic substance of microbial life.If total carbon is enough,volume weight and porosity will become the crucial substance when soil depth changed.According to the data of larch and birch plantation forest soil microorganism,we summarized the mechanism about the edge effect of soil microorganism,and provided reference data for forest protection and ecological restoration.