Response Characteristics Of Litter Decomposition With Different Masses To Altitude Gradient

Litter decomposition is an important biogeochemical process in ecosystems.It is not only related to the material exchange,energy transfer and the evolution of state systems,but also to the global C cycle and balance.Therefore,it's crucial to study the effect of climate change on litter decomposition.To explore the response of different quality litter decomposition to climate change,we selected litter with different quality(significant C/N difference)as the research object.Three experimental plot with different altitude(1200,700 and 200 m)in Wuyi Mountain were used as research platform.All the litter were placed across the elevation gradient,to study the response characteristics and dominant factors of different quality litter decomposition to altitude gradient.The main results are as follows:With the increases of decomposition time,the dry weight residual rate of each litter showed a steady downward trend.The dry weight residual rate of different litter had different responses to altitude.The dry weight residual rate of Pinus taiwanensis and Schima superba were highest at 700 m at some decomposition time.The dry weight residual rate of Phoebe bourmei and Cunninghamia lanceolata litter was only different on the 360 th day of decomposition,and both at 200 m were significantly higher than that at 1200 m and 700 m(P < 0.05).The dry weight residual rate of Castanopsis carlessi leaves did not differ among altitudes during each period of decomposition.The C content of litter did not vary with increasing time.The contents of N and P increased with the decomposition time,indicating that the release rate of C was approximately equal to the rate of mass loss.The release rate of N and P were were faster than the rate of their mass loss.The residual amounts of C,N and P showed an overall downward trend with the increase of decomposition time.The difference of C content and C residual rate of each litter type in the decomposition process is relatively obvious,followed by N content and residual rate,while the P content and residual rate of each litter have no difference among elevation during each period of decomposition.This indicates that the release rate of different types of nutrients also has different responses toaltitude.The extractables,cellulose and lignin residues of each litter decreased significantly with the increase of decomposition time.The response of the residual amount of litter to the elevation gradient significantly related to the litter quality and decomposition time.On the whole,there was greater difference on The 180 th day of decomposition than the day of 360.Litter quality is an important factor affecting the rate of litter decomposition.In this study,the N,extractables,cellulose,lignin content of leaves and C/N,C/P,N/P,lignin/N,lignin/P has significant effects on the decomposition of litter at three altitudes,but the effect of these indicators on the decomposition of litter changes with the elevation.The effect of litter quality on litter decomposition is generally discussed.At high altitude(1200 m),the decomposition rate of litter is more affected by the quality.It also shows that the quality of litter and the environment have obvious interaction with the decomposition of litter.The decomposition rate of different quality leaf litter has different response to altitude.In this study,the Decomposition factor of Pinus taiwanensis and Schima superba litter decreased firstly and then increased with altitude.The decomposition factor of Cunninghamia lanceolata and Phoebe bourmei decreased with altitude;Castanopsis carlesii The decomposition factor of Castanopsis carlesii litter did not differ significantly with elevation.The decomposition coefficients of Phoebe bournei,Pinus taiwanensis,Cunninghamia lanceolata,Schima superba,and Castanopsis carlesii were 35.67%,21.03%,21.27%,11.50%,and 8.88% respectively,indicating that compared with high quality litter(Schima superba and Castanopsis carlesii),the decomposition of low-quality litter(Phoebe bourmei,Pinus taiwanensis and Cunninghamia lanceolata)is more sensitive to altitude response.The variation characteristics of microbes along the altitude,especially GP/GN was the main reasons for the low sensitivity of low-quality litter along altitude.