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降水变化对荒漠草原土壤呼吸的影响
摘要点击 2283  全文点击 507  投稿时间:2020-12-22  修订日期:2021-03-05
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中文关键词  降水处理  土壤呼吸(SR)  地上生物量  土壤碳库  荒漠草原
英文关键词  precipitation treatment  soil respiration(SR)  aboveground biomass  soil carbon pool  desert grassland
作者单位E-mail
蒿廉伊 西北师范大学地理与环境科学学院, 兰州 730070 haolianyi2020@126.com 
张丽华 西北师范大学地理与环境科学学院, 兰州 730070 zhanglihualz@126.com 
谢忠奎 中国科学院西北生态环境资源研究院皋兰生态与农业综合试验站, 兰州 730000  
赵锐锋 西北师范大学地理与环境科学学院, 兰州 730070  
王军锋 西北师范大学地理与环境科学学院, 兰州 730070  
郭亚飞 西北师范大学地理与环境科学学院, 兰州 730070  
高江平 西北师范大学地理与环境科学学院, 兰州 730070  
中文摘要
      全球气候变化使得降水格局发生显著改变.土壤呼吸作为土壤碳库向大气释放CO2的重要途径,其对降水变化的响应可能会影响陆地生态系统碳循环进程,并对全球气候变化产生反馈作用,但目前关于土壤呼吸对降水变化的响应没有一致的结论.以黄土高原西部荒漠草原为对象,通过野外降水控制实验减水40%(-40%)、减水20%(-20%)、自然降水、增水20%(20%)和增水40%(40%),探究降水变化对土壤呼吸动态的影响及其与土壤含水量、土壤温度、地上生物量、土壤有机碳、微生物量碳和碳氮比(有机碳总氮比)等因素的关系.结果表明,在3 a期间不同降水处理下土壤呼吸的日变化呈现较一致的单峰和双峰模式.土壤呼吸随降水量的增加均呈增加趋势,且相较对照,土壤呼吸在降水控制实验第二年(偏湿年份)和第三年(偏干年份)表现出显著差异,表明降水变化对土壤呼吸产生了遗留效应.同时,相比对照,偏湿年土壤呼吸在-40%处理下显著最低,在40%处理下显著最高,土壤呼吸对减水处理的负响应强于对增水处理的正响应;偏干年土壤呼吸在增水处理下显著高于对照,且对增水处理的正响应明显强于减水处理.此外,土壤含水量、地上生物量、土壤有机碳和碳氮比是显著影响土壤呼吸的环境因子,且随降水量的增加而增加;土壤呼吸随土壤含水量、地上生物量、土壤有机碳和碳氮比的增加而增加,随微生物量碳的增加而减少,其中土壤含水量对土壤呼吸的解释率最高,这表明土壤含水量是控制荒漠草原区土壤呼吸的主要环境因子.无论在偏湿或偏干年份,降水变化下,植物生物量输入幅度均低于土壤呼吸输出幅度,表明降水变化可能不利于土壤碳固存,尤其偏干年份降水变化对碳库输出的影响更强.因此,荒漠草原区不同干湿年份降水变化对土壤呼吸的影响可能对生态系统碳循环过程产生不同的影响,进而为区域碳预算评估提供参考.
英文摘要
      Global climate change has significantly changed precipitation patterns. Soil respiration (SR), as an important pathway through which CO2 is released from the soil carbon pool into the atmosphere, may affect the carbon cycle process of terrestrial ecosystems and have a feedback effect on global climate change in response to precipitation change. However, at present there is limited understanding of how SR is affected by precipitation change. Field precipitation control experiments were conducted (with -40%, -20%, natural, 20%, and 40% precipitation) on desert grassland in the west of the Loess Plateau, to investigate the influence of precipitation change on SR dynamics and its relationship with soil water content, soil temperature, aboveground biomass, soil organic carbon, microbial biomass carbon, carbon-nitrogen ratio, and other factors. The results show that the diurnal variations of SR under different precipitation treatments were consistent in unimodal and bimodal models over three years. SR showed an increasing trend with added precipitation, relative to the control, and significant differences were observed between the second year (wetter) and the third year (drier) of the precipitation-manipulation experiment, indicating that precipitation changes had a legacy effect on SR. At the same time, SR was lowest under the -40% treatment and highest under the 40% treatment during the wetter year. The negative response of SR to precipitation exclusion treatments was stronger than the positive response to precipitation addition treatments. SR in drier years was significantly higher under precipitation addition treatments than the control, and the positive response of SR to increased precipitation treatment was significantly stronger than that under decreased precipitation treatment. In addition, soil water content, aboveground biomass, soil organic carbon, and carbon-nitrogen ratio were the environmental factors that obviously affected SR and increased with additional precipitation. SR increased with increases in soil water content, aboveground biomass, soil organic carbon, and carbon-nitrogen ratio, but decreased with increases in microbial biomass carbon. Among these factors, soil water content had the highest interpretation rate for SR, indicating that soil water content was the main environmental factor controlling SR in desert grassland. In both wetter and drier years, the amplitude of plant biomass input was lower than the amplitude of SR output under precipitation change, indicating that precipitation change may be unfavorable to soil carbon sequestration, especially in drier years, when precipitation change has a stronger influence on carbon pool output. Therefore, precipitation changes on SR in desert grassland in various dry and wet years may have different influences on the carbon cycle process of ecosystems, thus providing a reference for regional carbon budget assessment.

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