Effects Of Snow Depth And Soil Substrate On Soil Microbial Biomass Content And Their Stoichiometry

Soil microbe is the most important decomposer in forest ecosystems and sensitive indicator to enviromental changes.It plays a crucial role inforest carbon(Cmic)?nitrogen(Nmic)and phosphorus(Pmic)cycles.We use a chloroform fumigation extration method to measure and compare the dynamics of Cmic?Nmic and Pmic under different depth of snow cover and soil substrates.The results were listed as following:(1)The Cmic and Nmic of SP3 treatment were higher than that of SP1 treatment and SP2 treatment in the early snow cover period(December)of 0-5 cm and 5-10 cm soil layers.The Cmic and Nmic of SP1 treatment and SP2 treatment were significantly higher than that of SP3 treatment in the late snow cover period(March)(P<0.05),and the Cmic and Nmic of SP1 treatment and SP2 treatment were significantly higher than that of 0-5 cm soil layers in SP3 treatment.Other stages had no responding changes.(2)The Cmic and Nmic dropped first and rised in different treatments of 0-5 cm soil layer from december to august next year(V shape);The range of SP1?SP2 ? SP3 changes(Cmic)was 43.34-171.99 mmol kg-1?51.98-166.81 mmol kg-1,the range of SP1?SP2 ? SP3 changes(Nmic)was 12.00-33.97 mmol kg-1?12.31-33.77 mmol kg-1?11.34-34.11 mmol kg-1.The Cmic and Nmic dropped after rising first and then continue rise and declined in SP1 treatment and SP2 treatment of 5-10 cm soil layer from december to august next year(M shape).The Cmic and Nmic had the trend of decline in SP3 treatment;The range of SP1?SP2 ? SP3 changes(Cmic)was 39.93-79.59 mmol kg-1?41.00-87.44 mmol kg-1?45.65-83.85 mmol kg-1,the range of SP1?SP2 ? SP3 changes(Nmic)was 6.40-17.16 mmol kg-1?6.41-15.05 mmol kg-1?8.77-14.23 mmol kg-1.(3)The Cmic:Nmic had no significant difference among three treatments of 0-5 cm and 5-10 cm soil layers(P>0.05).The C:Nmic of three treatments had same annual dynamics in 0-5 cm soil layer.Relative to 0-5 cm soil layer,The Cmic:Nmic of 5-10 cm soil layer changed stability.(4)Before the successsion:the Cmic Nmic and Pmic of A treatment were significantly higher than that of B or C treatment(P<0.05).The Cmic:Nmic of A treatment was lower than that of B or C treatment,but the Cmic:Pmie and N:Pmic of A treatment were higher than those of B or C treatment.The Cmic/soil carbon(Csoii),Nmic/soil nitrogen(Nsoil),and Pmic/phosphorus(Psoil)of A treatment were significantly higher than those of B or C treatment(P<0.05,except for the Nmic/Nsoil,of C treatment).(5)After the succession:the Cmic,Nmic,and Pmic of A treatment were significantly higher than that of B or C treatment(P<0.05).The Cmic:Nmic of A or B treatment was lower than that of C treatment,but the Cmic:Pmic and Nmic:Pmic of A treatment were higher than those of B or C treatment.The Cmic/Csoii,Nmic/Nsoii,and Pmic/Psoii of A treatment were higher than those of B or C treatment.(6)Through 10-year succession,the Cmic,Nmic,and Pmic of the three treatments increased(C treatment had the largest increase including 145.35%,243.29%and 58.39%).The Cmic:Nmic of the three treatments declined,but the Cmic:Pmic and Nmic:Pmic increased.Among the-three treatments,the Cmic:Nmic of B and C treatments decreased significantly(P<0.05),while the N:Pmic of A and C treatments increased significantly(P<0.05).The Cmic/Csoil,Nmic/Nsoil,and Pmic/Psoii of three treatments increased with the succession.