The Effects Of Forest Fire On The Soil Characteristics And Charcoal Ecological Role In Burned Forests Of Larix Gmelinii (Rupr.)Kuzen

To investigate the effects of fire intensity on the soil microbial community of larch forests,we selected three kinds of sites including high intensity burned site,light intensity burned site and unburned site in the current year burning in the Great Xingan Mountain.Soils were sampled from 0-5cm and 5-10 cm separately in each site and were analyzed soil microbial characteristics by phospholipid fatty acid(PLFAs).The results showed that pH,total potassium,available phosphorus and clay and sand content were significantly compared with burned and unburned sites.The total soil microbial biomass,bacteria biomass,fungus biomass and frankia biomass were influenced by fire,but did not showed significantly different in three sites.However,the structure of soil microbial community indictors,such as G+/G-and F/B were significantly different compared high intensity burned site and other two sites.RDA analysis showed that G+/G-was influenced by soil water content and F/B was influenced by soil pH.These results indicated that at the current year of burning,soil water content and pH were critical factors that affected the structure of soil microbial community.To understand the effects of charcoal after forest fire on the germination of Larix gmelinii at Great Xingan Moutains,we investigated the charcoal distribution and collected different types of charcoal produced by trees(L.gmelinii and Betula platyphylla Suk.),shrub and grass,respectively.Moreover,we collected charcoals which were produced by different years(1,2,4 and 5 year)from the burned forest sites.The charcoals then were soaked into water at 12,24 48 or 96 hours to obtain different charcoal solution.Our results showed there were significant effects of different charcoal or different produced years on the germination of L.gmelinii?s seeds.However,the strength and directions of effects were randomly.These results indicated that the effects of charcoal were very complexity.In summary,soil characteristics and soil microbial community were influenced by fire intensity,especially by the high intensity fire.In the high intensity burned site,soil microbial community structure were significantly affected by soil water content and pH.Charcoal,however,were produced by different materials and different time,which significantly influenced the germination of L.gmelinii?s seeds.Thus,the variations of soil water,pH,soil microbial community should be focused on in the future study.The ecological role of charcoal in the forest rehabilitation still uncertain and be discussed in the future.