Effect Of Simulated Nitrogen Deposition On Decomposition Of Moso Bamboo Stump

Stump is one of the most important coarse woody debris in Moso bamboo forest ecosystem.The decomposition of stump plays an important role in nutrient cycling of ecosystem and productivity improvement of bamboo stands.At present,our understanding of decomposition and elements release of bamboo stump is largely inadequate,especially in the background of N deposition.In this study,we investigated the effects of N additions(control:0 kg N·hm^-2·yr^-1,low N:30 kg N·hm^-2·yr^-1,medium N:60 kg N·hm^-2·yr^-1,high N:90 kg N·hm^-2·yr^-1)on respiration,decomposition and elements release of bamboo stump.The results were as follows:(1)The decomposition rates of fine root,coarse root and root stump were 0.128,0.083 and 0.090,respectively.The decomposition rate of fine root was significantly higher than that of coarse root and root stump.(2)Compared to the control,high N addition significantly increased the decomposition rates of fine root and coarse root,and low and medium N treatments significantly increased the decomposition rate of root stump.(3)Compared to the control,N addition significantly increased annual CO₂ emissions of stumps with three harvest years,and decreased the temperature sensitivity coefficient(Q₁₀).(4)The loss of C,N,P and K in coarse root and fine root of1-year-old stump under control treatment were significantly lower than that of 5-year-old and 3-year-old stumps.The remaining of C,N,P,K,cellulose and lignin in coarse root and fine root of 1-year-old stump under all treatments had no significant change.(5)N addition accelerated the loss of C and N in the coarse root and fine root of 5-year-old and 3-year-old stumps.Our results show that N addition can promote the respiration and decomposition of bamboo stump,and accelerate the release of various elements.The results are beneficial to the establishment of nutrient cycling model and sustainable development of Moso bamboo forests under increasing N deposition.