The Response Of Litter Of Spruce-fir-Korean Pine Forest In Xiaoxing'anling To Temperature Increase And Nitrogen Deposition

Changes in global climate and environmental change,such as increased nitrogen deposition and climate warming,will continue to change the structure and function of ecosystems,interfering with the material cycle and energy flow of terrestrial ecosystems,threatening human health and survival,Aroused widespread concern from governments and scientists around the world.Changes in the litter decomposition process triggered by global environmental changes will directly affect the ecosystem carbon cycle and global carbon balance,and become the focus of global change research.In this study,the spatial translocation method was used to move the coniferous and broad-leaved leaf litter from the exogenous nitrogen addition plot(nitrogen addition started in May 2009)in Xiaoxing'anling Fenglin Nature Reserve to simulate the future warming.Nitrogen addition control test plots in Changbai Mountain Nature Reserve,Jilin Province at 3.2 °C(nitrogen addition began in May 2010),nitrogen application in both places was nitrogen application(LN 2.5g N m-2 a-1)and Control(CK 0gN m-2a-1).There were 4 treatments in this experiment,namely nitrogen application(LN),warming(WT),nitrogen application(WLN)and control(CK).The response of litter of different leaf types to the temperature increase,nitrogen deposition and their interaction in the Pinus sylvestris var.mongolica forest in Xiaoxing'anling area was studied,which provided a reference for similar research.The main findings are as follows:1.Under natural conditions,the decomposition rate of litter of different leaf types is broadleaf > coniferous > mixed leaf.The combination of temperature rise and nitrogen deposition is consistent with the natural state decomposition.In the case of nitrogen application,it becomes mixed leaf > broad leaf > needle.After the temperature rises,the decomposition rate is broadleaf > mixed leaf > needle.Nitrogen application,warming and the combination of both inhibited the decomposition and nutrient release of coniferous litter,and the decomposition and nutrient release of the mixed leaf litterwere firstly inhibited and promoted.In the late stage of nitrogen application,the decomposition of broadleaf litter and nutrient release were promoted.The interaction of warming and increasing nitrogen application promoted the decomposition of broadleaf litter and nutrient release.