In order to understand the effects of increasing atmospheric nitrogen （N） deposition on the subtropical bamboo ecosystem, a nearly six-year field experiment was conducted in a Pleioblastus amarus plantation in the r...In order to understand the effects of increasing atmospheric nitrogen （N） deposition on the subtropical bamboo ecosystem, a nearly six-year field experiment was conducted in a Pleioblastus amarus plantation in the rainy region of SW China, near the western edge of Sichuan Basin. Four N treatment levels---control （no N added）, low- N （50 kg N ha-1 a-l）, medium-N （150 kg N ha-1 a-l）, and high-N （300 kg N ha-1 a-1）--were applied monthly in the P. amarus plantation starting in November 2007. In June 2012, we collected intact soil cores in the bamboo plantation and conducted a 30-day laboratory incubation experiment. The results showed that the soil N net miner- alization rate was 0.96 4- 0.10 mg N kg-1 day-1, under control treatment. N additions stimulated the soil N net mineralization, and the high-N treatment significantly increased the soil N net mineralization rate compared with the control. Moreover, the soil N net mineralization rate was significantly and positively correlated with the fine root biomass, the soil microbial biomass nitrogen content and the soil initial inorganic N content, respectively,whereas it was negatively correlated with the soil pH value. There were no significant relationships between the soil N net mineralization rate and the soil total nitrogen （TN） content and the soil total organic carbon content and the soil C/N ratio and the soil microbial biomass carbon con- tent, respectively. These results suggest that N additions would improve the mineral N availability in the topsoil of the P. amarus plantation through the effects of N additions on soil chemical and physical characteristics and fine-root biomass.展开更多
基金supported by the National Natural Science Foundation of China(No.31300522)Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20125103120018)
文摘In order to understand the effects of increasing atmospheric nitrogen （N） deposition on the subtropical bamboo ecosystem, a nearly six-year field experiment was conducted in a Pleioblastus amarus plantation in the rainy region of SW China, near the western edge of Sichuan Basin. Four N treatment levels---control （no N added）, low- N （50 kg N ha-1 a-l）, medium-N （150 kg N ha-1 a-l）, and high-N （300 kg N ha-1 a-1）--were applied monthly in the P. amarus plantation starting in November 2007. In June 2012, we collected intact soil cores in the bamboo plantation and conducted a 30-day laboratory incubation experiment. The results showed that the soil N net miner- alization rate was 0.96 4- 0.10 mg N kg-1 day-1, under control treatment. N additions stimulated the soil N net mineralization, and the high-N treatment significantly increased the soil N net mineralization rate compared with the control. Moreover, the soil N net mineralization rate was significantly and positively correlated with the fine root biomass, the soil microbial biomass nitrogen content and the soil initial inorganic N content, respectively,whereas it was negatively correlated with the soil pH value. There were no significant relationships between the soil N net mineralization rate and the soil total nitrogen （TN） content and the soil total organic carbon content and the soil C/N ratio and the soil microbial biomass carbon con- tent, respectively. These results suggest that N additions would improve the mineral N availability in the topsoil of the P. amarus plantation through the effects of N additions on soil chemical and physical characteristics and fine-root biomass.
