Soil Microorganism And Activities Of Soil Enzyme In Larix Gmelinii Forest Of Daxingan Mountains

Soil microorganisms are main parts of the forestry ecosystem, and play vital roles in energy conversion, material cycling, development and maturation of soil. They are sensitive indicatives of any variation in environmental conditions. Both species constitution and quantity of soil microorganisms come to be the key parameters for evaluating the soil quality. So investigating ecological distribution of soil microorganisms and activities of enzyme about Larix gmelinii forest in the national forestry ecosystem station of Inner Mongolia Great Xingan Mountains, they are important theoretical and practical significance in resuming and controlling degraded ecosystem and improving the productivity of different vegetation.In this study, we use traditional isolation methods of microorganisms to research the species constitution and quantity of soil microorganisms in Larix gmelinii forest of the Great Xingan Mountains, and to examine their relationships with soil microbial quantity, soil properties and soil enzymes. Morphology and rDNA-ITS are used to identify soil dominant fungi. The key results from these studies are summarized as follows:1. Soil pH value are 4.59-5.94 and acid in the Larix gmelinii virgin and disturbed forest. Soil organic matter is relatively high in the surface of soil. In addition to total K, other nutrients of soil are gradual lower with the increasing in vertical depth, but total K is contrary.2. The quantity of soil microorganisms show significant changes in different seasons. They are different in different plots, as follows:â‘ The quantity of total microorganisms and bacteria: in all plots of virgin forest and LFB plot of distributed forest, they are July>May and September, but in CL and SL plots of disturbed forest, they are May>July and September.â‘¡The quantity of fungi: they are September>May>July in the LLV plots of virgin forest, and are July >May> September in the other plots.â‘¢The quantity of actinomycetes: they are May > September and July in LLV and BLV plots of virgin forest and CL plot of disturbed forest, and they are July>May and September in HLV plot of virgin forest and LFB plot of disturbed forest, but they are September>May and July in SL plot of disturbed forest. The quantity of soil microorganisms are gradual lower with the increasing in vertical depth, follow orders: 0-10cm layer>10-20cm layer>20-30cm layer.3. By using of traditional culture methods, bacteria isolated from Larix gmelinii forest belong to 21 genera, Ramibacterium, Bacillus, Corynebacterium and Brevibacterium are dominant genera; fungi are composed of 21 genera, Penicillium, Aspergillus,Mucor and Trichoderma are dominant genera; actinomycetes are classified into 9 genera,Streptomyces and Nocardia are main genera.4. Correlation analysis of soil properties and microbial quantity show that soil total microorganisms and bacteria have very significant positive correlation with available N (P<0.01), and have significant positive correlation with total N (P<0.05). Among soil microorganisms, bacteria have very significant positive correlation with total microorganisms and fungi (P<0.01), fungi have very significant positive correlation with total microorganisms (P<0.01).5. By using of molecular identification, 14 different strains of Penicillium belong to 10 different species; five different strains of Aspergillum belong to five different species; four strains of Trichoderma belong to four different species, and two species are its sexual stages; three different strains of Mucor belong to two different species.6. Seasonal variation of soil enzymes are July>May and September. The activities of soil enzymes are gradual lower with the increasing in vertical depth, follow orders: 0-10cm layer>10-20cm layer>20-30cm layer.7. Correlation analysis of soil enzymes and soil properties show that invertase has significant negative correlation with pH values (P<0.05), protease has significant positive correlation with total P and available N (P<0.05), and then has significant negative correlation with available K (P<0.05), acid phosphatase has very significant negative correlation with available K (P<0.01). Among the activities of soil enzymes, polyphenol oxidase has significant positive correlation with acid phosphatase (P<0.05), protease has significant positive correlation with acid phosphatase (P<0.05).8. Correlation analysis of soil enzymes and soil microorganisms show that the protease has very significant positive correlation with total microorganism and bacteria (P<0.01), acid phosphatase has significant positive correlation with total microorganism, bacteria and fungi (P<0.05), protease has significant positive correlation with fungi (P<0.05).