Effects Of Warming And Nitrogen Deposition On Leymus Chinensis And Phragmites Communis Litter Decomposition

This thesis focuses on Leymus chinensis and Phragmites communis litter in Songnen Plain. Treatments were designed as warming and nitrogen deposition, with six replicates in each treatment. The research on the decomposition rate, organic C content, nitrogen content, phosphorus content and biomass of microorganism in L.chinensis and P. communis litter was completed during the period from May to November 2007.The decomposition rate of L. and P. communis litter hump happened in July were 0.019 g·g^-1·d^-1和0.015 g·g^-1·d^-1. Nitrogen deposition made decomposition rate of L. chinensis and P. communis litter increasing(P<0.01).Warming + nitrogen deposition had obvious effect on litter decomposition rate (P<0.05). The effect of warming was unmarked (P>0.05).Warming and nitrogen deposition had interaction on the decomposition rate of Leymus chinensis and Phragmites communis litter. The effect of three treatment on the decomposition rate of L. chinensis and P. communis litter were similar : Nitrogen deposition>Warming + nitrogen deposition>warming.Nitrogen deposition on nitrogen content of L. chinensis and P. communis litter were higher. Analysis of variance(ANOVA)indicated was significantly (P<0.01). The effect of warming on nitrogen content was unmarked (P>0.05). The effect of three treatment on carbon content was significant. Effect of warming + nitrogen deposition on L. chinensis litter organic C content lost mostly, was 509.2g·kg^-1 . The effect of three treatment on L. chinensis litter organic C content lost were more than P.communis litter. Warming and nitrogen deposition had significantly effect on phosphorus content of litter. Warming and nitrogen deposition had significantly interaction on organic C content, nitrogen content and phosphorus content.The decomposition rate of L. chinensis and P. communis litter were negatively related to P content . The effect of three treatment on C/P and N/P both increased at beginning, then dropped down. The decomposition rate of litter showed the similar rule,but C/N did not have this rule. The decomposition rate of L.chinensis litter was positive relation with C/P and N/P(P<0.05). The decomposition rate of P. communis litter was positive relation with C/P and N/P obviously(P<0.01).The effect of three treatment on the biomass of microorganism was obvious. The maximum hanppened in September and October . Warming and nitrogen deposition had interaction on the biomass of microorganism except the biomass of actinomyces in L. chinensis litte.