Simulated warming enhances the responses of microbial N transformations to reactive N input in a Tibetan alpine meadow. (August 2020)

• Record Type: Journal Article
• Authors: Zhang, Yi; Zhang, Nan; Yin, Jingjing; Zhao, Yexin; Yang, Fei; Jiang, Zhongquan; Tao, Jinjin; Yan, Xuebin; Qiu, Yunpeng; Guo, Hui; Hu, Shuijin
• Is Part Of: Environment international. Volume 141(2020)
• Publication Date: 2020-08
• Subjects: Alpine meadow -- Climate warming -- Nitrogen addition -- N2O emission -- Ammonia-oxidizing archaea -- Ammonia-oxidizing bacteria; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2020.105795
• Languages: English
• ISSNs: 0160-4120

Abstract

Highlights: Responses of alpine soil N transformations to warming and N input were examined. Warming alone did not significantly affect soil N transformations. N input significantly increased AOB and N2 O emissions in the late growing season. Warming amplified the effects of N input on nitrification and N2 O emissions. Ammonia-oxidizing bacteria dominate alpine soil N transformations and N2 O emission. Abstract: Alpine ecosystems worldwide are characterized with high soil organic carbon (C) and low mineral nitrogen (N). Climate warming has been predicted to stimulate microbial decomposition and N mineralization in these systems. However, experimental results are highly variable, and the underlying mechanisms remain unclear. We examined the effects of warming, N input, and their combination on soil N pools and N-cycling microbes in a field manipulation experiment. Special attention was directed to the ammonia-oxidizing bacteria and archaea, and their mediated N-cycling processes (transformation rates and N2 O emissions) in the third plant growing season after the treatments were initiated. Nitrogen input (12 g m −2 y −1 ) alone significantly increased soil mineral N pools and plant N uptake, and stimulated the growth of AOB and N2 O emissions in the late growing season. While warming (by 1.4 °C air temperature) alone did not have significant effects on most parameters, it amplified the effects of N input on soil N concentrations and AOB abundance, eliciting a chain reaction that increased nitrification potential (+83%), soil NO3 − -N (+200%), and N2 O emissions (+412%) across the whole season. Also, N input reduced AOB diversity but increased the dominance of genus Nitrosospira within the AOB community, corresponding to the increased N2 O emissions. These results showed that a small temperature increase in soil may significantly enhance N losses through NO3 − leaching and N2 O emissions when mineral N becomes available. These findings suggest that interactions among global change factors may predominantly affect ammonia-oxidizing microbes and their mediated N-cycling processes in alpine ecosystems under future climate change scenarios.