干旱气象 ›› 2022, Vol. 40 ›› Issue (3): 354-363.DOI: 10.11755/j.issn.1006-7639(2022)-03-0354

• 论文 • 上一篇    下一篇

黄土高原半干旱区2020年生长季草地土壤呼吸特征及其影响因素

张琳焓1,3(), 闭建荣1,2,3(), 张雪腾1,3, 李正鹏1,3, 赵长明4,5, 马晓俊5   

  1. 1.兰州大学大气科学学院,半干旱气候变化教育部重点实验室,甘肃 兰州 730000
    2.西部生态安全省部共建协同创新中心,甘肃 兰州 730000
    3.甘肃省半干旱气候与环境野外科学观测研究站,甘肃 兰州 730000
    4.兰州大学生命科学学院,甘肃 兰州 730000
    5.兰州大学科学观测台站管理中心,甘肃 兰州 730000
  • 收稿日期:2022-01-20 修回日期:2022-04-11 出版日期:2022-06-30 发布日期:2022-06-28
  • 通讯作者: 闭建荣
  • 作者简介:张琳焓(1993—),女,硕士生,主要从事陆地碳循环过程研究. E-mail: zhanglh2019@lzu.edu.cn
  • 基金资助:
    甘肃省野外科学观测研究站建设项目(18JR2RA013);甘肃省科技重大专项项目(18ZD2FA009);兰州大学中央高校基本科研业务费专项(lzujbky-2022-kb02);兰州大学中央高校基本科研业务费专项(lzujbky-2022-sp04)

Grassland soil respiration characteristics and their influencing factors in semi-arid region of Loess Plateau during the growing season in 2020

ZHANG Linhan1,3(), BI Jianrong1,2,3(), ZHANG Xueteng1,3, LI Zhengpeng1,3, ZHAO Changming4,5, MA Xiaojun5   

  1. 1. College of Atmospheric Sciences, Lanzhou University, Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, Lanzhou 730000, China
    2. Collaborative Innovation Center for Western Ecological Safety, Lanzhou 730000, China
    3. Field Scientific Observation and Research Station of Semi-arid Climate and Environment of Gansu Province, Lanzhou 730000, China
    4. School of Life Sciences, Lanzhou University, Lanzhou 730000, China
    5. Management Center of Scientific Observing Stations, Lanzhou University, Lanzhou 730000, China
  • Received:2022-01-20 Revised:2022-04-11 Online:2022-06-30 Published:2022-06-28
  • Contact: BI Jianrong

摘要:

采用LI-8100A型土壤碳通量仪对黄土高原半干旱区草地生长季(5—10月)的土壤呼吸速率、土壤温度及含水量进行连续观测,综合分析土壤呼吸的时间变化规律,并研究环境因子对呼吸速率的影响。结果表明:(1)不同天气条件下土壤呼吸速率的日动态变化差异明显,晴天的日均值 (2.90 µmol·m-2·s-1)与变化范围(1.73~4.92 µmol·m-2·s-1)明显大于多云天和阴天。不同月份土壤呼吸速率的平均日变化均呈现“单峰型”结构,最高值(2.20~4.40 µmol·m-2·s-1)、最低值(0.71~1.70 µmol·m-2·s-1)分别出现在12:00或13:00、05:00或06:00,日均值接近于10:00或19:00的观测值。(2)白天和夜间土壤呼吸速率在5—6月处于较小值,从6月开始逐渐增大,8月达到峰值(白天3.31±0.98 µmol·m-2·s-1、夜间1.80±0.39 µmol·m-2·s-1),之后逐渐减小,10月出现最低值(白天1.55±0.55 µmol·m-2·s-1、夜间0.81±0.12 µmol·m-2·s-1),且白天通常高于夜间。整个生长季夜间土壤呼吸对全天总呼吸的贡献率为27.2%~32.4%。因此,在当前草地生态系统碳循环模型中应考虑夜间土壤呼吸的影响。(3)土壤温度是影响生长季土壤呼吸速率的主要环境因子,但土壤温度单变量模型不足以全面解释土壤呼吸的动态变化。结合土壤温度与含水量的双变量非线性模型能更好地拟合土壤呼吸速率,对其变异的解释程度达74.0%。(4)2020年生长季,全天、白天和夜间土壤呼吸的温度敏感性指数(Q10)变化范围分别为1.38~2.14、1.22~1.96和0.85~1.64,对应平均值分别为1.58±0.23、1.41±0.19和1.20±0.16。如果只用白天时段的Q10值代替日均值,将造成约10.8%的低估。

关键词: 土壤呼吸速率, 土壤温度, 土壤含水量, Q10值, 黄土高原半干旱区

Abstract:

The automated soil CO2/gas flux system (model LI-8100A) was used to continuously observe the soil respiration rate, soil temperature and water content in a semi-arid grassland of Loess Plateau during the growing season (from May to October). The temporal variations of soil respiration were comprehensively analyzed, and the influences of environmental hydrothermal factors on soil respiration were studied. The results are as follows: (1) The diurnal dynamic variations of soil respiration rate were significantly different under diverse weather conditions, and the daily mean value (2.90 µmol·m-2·s-1) and variation range (1.73-4.92 µmol·m-2·s-1) on sunny days were obviously greater than those on cloudy and overcast days. The average diurnal variations of soil respiration rate in different months all showed a significant unimodal pattern, with the maximum (2.20-4.40 µmol·m-2·s-1) appearing at 12:00 BST or 13:00 BST and the minimum (0.71-1.70 µmol·m-2·s-1) appearing at 05:00 BST or 06:00 BST. The daily mean values were close to the observed values at 10:00 BST or 19:00 BST. (2) The soil respiration rate in both daytime and nighttime were low in May and June, and increased gradually from June, then reached the peak value (in daytime 3.31±0.98 µmol·m-2·s-1, in nighttime 1.80±0.39 µmol·m-2·s-1) in August, afterwards gradually decreased. Furthermore, the lowest value occurred in October (in daytime 1.55±0.55 µmol·m-2·s-1, in nighttime 0.81±0.12 µmol·m-2·s-1), and soil respiration rates in daytime were always higher than those in nighttime. The nocturnal soil respiration contributed 27.2%-32.4% to the total respiration during the whole growing season. Therefore, the effects of nocturnal soil respiration should be considered in the current carbon cycle models of grassland ecosystem. (3) Soil temperature was the main environmental factor affecting soil respiration rate, but the univariate model of soil temperature was not enough to fully explain the diurnal dynamic changes of soil respiration. The bivariate nonlinear model combined with soil temperature and water content could be better fitted the soil respiration rate and accounted for 74.0% of the variation. (4) The temperature sensitivity indices (Q10) of the entire day, daytime, and nighttime throughout the growing season in 2020 varied from 1.38 to 2.14, from 1.22 to 1.96, and from 0.85 to 1.64, respectively, with the corresponding mean values of 1.58±0.23, 1.41±0.19 and 1.20±0.16. This suggested that replacing the daily mean values of Q10 with daytime averages would result in an underestimation of about 10.8%.

Key words: soil respiration rate, soil temperature, soil water content, Q10 value, semi-arid region of Loess Plateau

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