The Influence Of Nitrogen Additions On Carbon Mineralization Under Different Temperature In Mid-subtropical Forests

Nitrogen deposition and global warming each have potential to alter soil carbon storage via changing decomposition,but combined effects of N addition and temperature on CO2 production in forest soils are less studied.Our objective was to investigate the influence of nitrogen additions on soil carbon mineralization under different temperature in Castanopsis kawakarnii and Cunninghamia lanceolata forests.Each kinds of soil set 3 temperature levels(10,20,30?)and 3 nitrogen addition levels(N1,N2,N3).We found that N addition and temperature had a negative and positive effect on CO2 production(P<0.001),respectively.Nitrogen addition and temperature change have a significant interaction in Castanopsis kawakarnii forest soil.Nitrogen addition had no significant effect on soil organic carbon mineralization under 10?,to produce inhibition under 20,30?.And the inhibition under 20? was best serious.And nitrogen addition have a nonsignificant interaction under different temperature in Cunninghamia lanceolata forest soil.Nitrogen addition had no significant effect on soil organic carbon mineralization under 10?,to produce inhibition under 20,30?.But there were not significant effect between the two temperatures.Temperature and nitrogen increased were significantly reduced soil total PLFA in Castanopsis kawakarnii and Cunninghamia lanceolata forests,aslo reduced gram-positive bacteria and gram-negative bacteria,fungi,bacteria content in Castanopsis kawakarnii.Temperature increased reduced the Cunninghamia lanceolata forests soil gram-positive bacteria and gram-negative bacteria,fungi,radiation bacteria content,but nitrogen addition had no significant effect on gram-positive bacteria.Temperature increased had positive of change gram-positive bacteria:gram-negative bacteria,reduced the fungi:bacteria.Nitrogen added only reduces fungi:bacteria in Castanopsis kawakarnii forest,and reduced gram-positive bacteria:gram-negative bacteria in Cunninghamia lanceolata forests.