Short-term responses of ecosystem respiration to warming and nitrogen addition in an alpine swamp meadow

• Published in: European Journal of Soil Biology
• Main Authors: Bai, Wei, Wang, Genxu, Xi, Jingyang, Liu, Yongwan, Yin, Pengsong
• Format: Report
• Language: English
• Published: ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER 2019
• Subjects: Warming; Nitrogen addition; Ecosystem respiration; Alpine swamp meadow; Qinghai-Tibetan plateau; SOIL RESPIRATION; CLIMATE-CHANGE; CARBON-CYCLE; MICROBIAL BIOMASS; PLANT-PRODUCTION; CO2; TEMPERATURE; PLATEAU; EMISSION; IMPACTS; Environmental Sciences & Ecology; Agriculture; Ecology; Soil Science; permafrost
• Online Access: http://ir.imde.ac.cn/handle/131551/26232; https://doi.org/10.1016/j.ejsobi.2019.04.003

Information regarding the interactive effects of global warming and increasing nitrogen (N) deposition on CO2 emissions in the alpine grassland ecosystem is scarce, especially in the permafrost region of the Qinghai-Tibetan Plateau. We conducted a manipulative field experiment in an alpine swamp meadow to investigate the responses of ecosystem respiration (ER) to simulated warming and N addition. Results showed that the interaction between warming and N addition significantly increased ER by 41.3-239.6%, which might be related to the enhancements in plant autotrophic respiration and soil microbial biomass and activity. The correlations between ER and a single hydrothermic factor tended to be weakened with the increasing complexity of the treatment method. The drought stress on CO2 emissions was not found due to the thawing of the permafrost and the upward diffusion of soil moisture, thus air temperature combined with soil temperature explained 80% of the ER fluctuations. Meanwhile, warming increased the aboveground biomass (AGB) and belowground biomass (BGB) by 44.2-68.1% and 48.1-82.6%, respectively, suggesting that more biomass was allocated to the belowground components. N addition increased AGB by 21.2-30.3%, while there was no significant effect on BGB. Warming combined with N addition strongly increased AGB and BGB by 52.0-159.5% and 59.0-102.1%, respectively. These results indicated that plant production and allocation pattern might also be important factors affecting CO2 emissions. In addition, warming alone and warming combined with N addition increased soil microbial biomass carbon (MBC) by 19.1-90.7% and 28.1-80.4%, respectively, and the enhancement in soil microbial biomass and activity might promote the release of soil carbon.