Decomposition of Leymus chinensis and Phragmites communis litter responses to simulated warming and nitrogen application in Songnen grassland

This thesis focused on Leymus chinensis and Phragmites communis litter in Songnen grassland.Infrared heater was used to increase the temperature.The simulation of nitrogen deposition was made by applying fertilizer.The responses of litter decomposition to warming and nitrogen application was examined.The result showed that warming and nitrogen application both significant increased litter decomposition rates in a certain extent.The order of decomposition residual rate of L.chinensis were warming+nitrogen application(69.30%),nitrogen application(75.75%),warming(81.20%),control(83.80%);The order of decomposition residual rate of P.communis were warming+nitrogen(78.85%),nitrogen application(83.25%),control(85.60%),warming(86.50%).Warming and nitrogen application treatments shortened the decomposition periods of L.chinensis and P.communis litter by Olson model.The linear regression showed that the regression coefficient of bacteria was the max among four treatments of two species;can explain that bacterial biomass was the most important factor during litter decomposition.In the course of litter decomposition,the relatedness of litter decomposition quality with organic C content was positively positive correlation.The content of total nitrogen and total phosphorus in litter have existed settling phenomena.