In order to understand the response of soil enzyme to nitrogen deposition,four treatments,namely bare soil (BS),Pinus massoniana litter (PL),Cunninghamia lanceolata litter (CL) and Schima superba litter (SL) were set in simulated natural nitrogen deposition (30 kg N·hm-2·a-1),respectively in this study.The dynamic changes of litter decomposition of different plant (P.massoniana,C.lanceolata and S.superba) and activities of asparaginase and cellulase were analyzed during early stage of leaf litter decomposition with the constant temperature and soil water content.The results showed that the decomposition rate of C.lanceolata leaf litter was the highest,with the S.superba leaf litter in the medium and the lowest for P.massoniana leaf litter at the end of experiment.With the exogenous nitrogen accumulation and the leaf litter decomposition,total nitrogen content of leaf litter increased while C ∶ N ratio of leaf litter decreased.The value of soil pH decreased significantly.And The nitrogen availability increased distinctly by adding ammonium nitrate.The activity of cellulase was promoted by exogenous nitrogen input,but soil asparaginase activity was inhibited,inversely.Cellulase activity in soil was inhibited by the leaf litter decomposition at the early stage,but promoted at the medium and last of litter decomposition process.However,the effect of leaf litter decomposition on asparaginase activity have no significant regularity.Therefore,nitrogen cycle will change the soil C ∶ N ratio in forest,thus affect material circulation and energy flow of the forest ecosystem.
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