Nitrogen(N)deposition has a profound influence on forest soil carbon(C)and N pools,but there was no consensus on the responses of different C and N components in different forest types.In this study,a two-year simulat...Nitrogen(N)deposition has a profound influence on forest soil carbon(C)and N pools,but there was no consensus on the responses of different C and N components in different forest types.In this study,a two-year simulated N deposition experiment with four levels of N(NH4NO3)-addition treatments(0,50,100,and 150 kg N/hm^(2)·a)were conducted in Larix gmelinii(LG)and Quercus mongolica(QM)plantation in Northeast China,in order to investigate the C and N pool dynamics under continuously enhanced N deposition.Soil organic carbon(SOC),soil total N(STN)and their active components(readily oxidizable C,ROC;dissolved organic C,DOC;microbial biomass C,MBC,dissolved organic N,DON;microbial biomass N,MBN)of the forest soil were measured monthly from May to October 2017.C and N contents in LG were observed higher than in QM.N addition had no effect on SOC and STN of LG,but significantly increased SOC and STN of QM at low N addition level.Low N addition generally raised active C components(ROC,DOC,and MBC)in both plantations,whereas high N addition did not significantly affect these components,or even decreased ROC in LG soil.Low N addition also increased STN and MBN of QM,while no significant change in STN and MBN of LG was observed.DON was directly affected by N addition and increased significantly with elevated N addition levels.The results indicated that N addition,especially of low rate,might enhance the C sequestration capacity of the forest soils and mitigate climate change.展开更多
基金This work was supported by the National Key Research and Development Program of China(grant No.2016YFD0200304,2017YFC0504205).
文摘Nitrogen(N)deposition has a profound influence on forest soil carbon(C)and N pools,but there was no consensus on the responses of different C and N components in different forest types.In this study,a two-year simulated N deposition experiment with four levels of N(NH4NO3)-addition treatments(0,50,100,and 150 kg N/hm^(2)·a)were conducted in Larix gmelinii(LG)and Quercus mongolica(QM)plantation in Northeast China,in order to investigate the C and N pool dynamics under continuously enhanced N deposition.Soil organic carbon(SOC),soil total N(STN)and their active components(readily oxidizable C,ROC;dissolved organic C,DOC;microbial biomass C,MBC,dissolved organic N,DON;microbial biomass N,MBN)of the forest soil were measured monthly from May to October 2017.C and N contents in LG were observed higher than in QM.N addition had no effect on SOC and STN of LG,but significantly increased SOC and STN of QM at low N addition level.Low N addition generally raised active C components(ROC,DOC,and MBC)in both plantations,whereas high N addition did not significantly affect these components,or even decreased ROC in LG soil.Low N addition also increased STN and MBN of QM,while no significant change in STN and MBN of LG was observed.DON was directly affected by N addition and increased significantly with elevated N addition levels.The results indicated that N addition,especially of low rate,might enhance the C sequestration capacity of the forest soils and mitigate climate change.
