The Soil Microbial Biomass To Simulated Warming And Nitrogen Deposition In Songnen Grassland: A Comparative Study

Elevated atmospheric CO2concentration, causes of global warming, industrial fuelemissions, extensively use of fertilizer increased the atmospheric nitrogen content, whichbrought a series of ecological and environmental problems. The Soil microbes have animportant role for the decomposition of organic matter and nutrient cycling, the warming andnitrogen deposition will inevitably have some impact on soil microbes. Therefore, to carry outcomparative studies of soil microbial response to warming and nitrogen deposition and itsrelease has important theoretical significance. For this reason, we simulated warming andnitrogen deposition controlled experiment in Songnen grassland field conditions and discussedthe response mechanisms and dynamics of soil microbial biomass, as well as the response ofthe soil microbial biomass and soil recovery after stopping the experiment.Under the condition of simulated warming and nitrogen deposition, in2008-2010, soilmicrobial biomass carbon(SMBC), soil microbial biomass nitrogen(SMBN) had no significantdifference in2008and2009;2010compared with2008declined significantly; no significantdifference between soil microbial biomass phosphorus(SMBP) inter-annual. But the changetrend of the soil microbial biomass C, N and P with the seasons was consistent and assumedunimodal trend, spring was lower, the highest in summer, the autumn began to decline.After warming and nitrogen addition treatments discontinued,2011-2012compared with2008-2010, SMBC and SMBN contents decreased significantly (P<0.05), SMBP contentsignificantly increased (P<0.05).2011-2012, SMBC and SMBN differences between thegroups were not significant, but under the influence of warming and nitrogen treatment a fewyears ago, compared with controls, warming, nitrogen addition and warming+nitrogenaddition still had a tendency to increase SMBC, SMBN, but the increasing trend was graduallyreduced. The annual changes of SMBP content was not significant in2011-2012.Correlation analysis showed that SMBC and soil total carbon, SMBN and soil totalnitrogen were significantly positive correlation, SMBP and SMBN showed significantlynegative correlation. Songnen grassland soil microbial biomass and soil nutrients had a goodcorrelation. Therefore, soil microbial biomass C, N, P could reflect the variation of soilnutrients.