Variations Of Soil Characteristics And Community Structure Of The Burn Area In Different Restoration Periods Of Gen He

Larix gmelinii was an important forest resource in China,it played an important role in maintaining ecological balance in the Greater Hinggan Mountains.The Greater Khingan Mountains area was a high incidence of forest fires.Our research object was the Larix gmelinii forest of different restoration stages.We researched soil chemical characteristics,soil microbial biomass,soil enzyme activity,species diversity and biomass in the burn area of different restoration stages,influence factors of soil microbial biomass and influencing factors soil enzyme activity were analysed by Pearson correlation analysis,influencing factors of shrub and herb species were analysed by RDA,it provided a theoretical basis for the Larix gmelinii community reconstruction in the burn area of the Greater Hinggan Mountains.The results show that:(1)The soil nutrient content of burn areas was kept at a low level in a short period.In the chronosequence of shrub and herb,forest fire influenced significantly the depth of 0～5cm soil layer p H,available nitrogen,ROC,TN,DOP,microbial biomass and enzyme activity in a short period.From the chronosequence of Birch to the chronosequence of Larix gmelinii,tree species replacement influenced the depth of 0～5cm soil layer p H,SOC and available nitrogen.(2)The influencing factors of soil microbial biomass were different in different restoration stages.In the chronosequence of shrub and herb,correlation analysis showed that the enzyme activity was limited by soil nitrogen in different restoration stages,the microbial biomass in 0～5cm and 5～20cm soil layer was limited by soil carbon and nitrogen.In the chronosequence of Birch,the microbial biomass in 0～5cm and 5～20cm soil layer was limited by carbon and phosphorus nutrients.In the chronosequence of Larix gmelinii,the microbial biomass in 0～5cm and 5～20cm soil layer was limited by soil nitrogen nutrients.(3)The species diversity and biomass changed in different restoration stages.In the chronosequence of shrub and herb,Birch seedlings were dominant species.The species diversity index of shrub and herb decreased in a short period.Forest fire influenced significantly Birch seedlings and Larch seedlings.From the chronosequence of Birch to the chronosequence of Larch,Larch seedlings were dominant species,forest fire increased the biomass of shrub,but the species diversity and biomass of herb decreased.(4)The influencing factors of species diversity were different in different restoration stages.In the chronosequence of shrub and herb,influencing factors of shrub species diversity in 0～5cm and 5～20cm soil layer were soil carbon and nitrogen content.In the chronosequence of Birch,influencing factors of shrub species diversity in 0～5cm soil layer were TN and MBP.In the chronosequence of Larch,influencing factors of shrub species diversity in 0～5cm and 5～20cm soil layer were soil carbon content,phosphorus content and microbial biomass.In the chronosequence of Birch and Larch,influencing factors of herb species diversity in 0～5cm and 5～20cm soil layer were p H and LAP.(5)The influencing factors of shrub and herb species were the same in different restoration stages Influencing factors of shurb species in 0～5cm soil layer were p H.In 5～20cm soil layer,influencing factors of shurb species were available nitrogen,and influencing factors of herb species were soil nitrogen content.