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  

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

作　　者：张琳焓 闭建荣[1,2,3] 张雪腾 李正鹏 赵长明 马晓俊[5] ZHANG Linhan;BI Jianrong;ZHANG Xueteng;LI Zhengpeng;ZHAO Changming;MA Xiaojun(College of Atmospheric Sciences,Lanzhou University,Key Laboratory for Semi-Arid Climate Change of the Ministry of Education,Lanzhou 730000,China;Collaborative Innovation Center for Western Ecological Safety,Lanzhou 730000,China;Field Scientific Observation and Research Station of Semi-arid Climate and Environment of Gansu Province,Lanzhou 730000,China;School of Life Sciences,Lanzhou University,Lanzhou 730000,China;Management Center of Scientific Observing Stations,Lanzhou University,Lanzhou 730000,China)

机构地区：[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

出　　处：《干旱气象》2022年第3期354-363,共10页Journal of Arid Meteorology

基　　金：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,lzujbky-2022-sp04)共同资助。

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(2.90μmol·m^(-2)·s^(-1))与变化范围(1.73~4.92μmol·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(2.20~4.40μmol·m^(-2)·s^(-1))、最低值(0.71~1.70μmol·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±0.98μmol·m^(-2)·s^(-1)、夜间1.80±0.39μmol·m^(-2)·s^(-1)),之后逐渐减小,10月出现最低值(白天1.55±0.55μmol·m^(-2)·s^(-1)、夜间0.81±0.12μmol·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(Q;)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Q;值代替日均值,将造成约10.8%的低估。The automated soil CO;/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(2.90μmol·m^(-2)·s^(-1))and variation range(1.73-4.92μmol·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(2.20-4.40μmol·m^(-2)·s^(-1))appearing at 12:00 BST or 13:00 BST and the minimum(0.71-1.70μmol·m^(-2)·s^(-1))appearing at 05:00 BST or 06:00 BST.The daily mean values were close to the observed values at10:00 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±0.98μmol·m^(-2)·s^(-1),in nighttime 1.80±0.39μmol·m^(-2)·s^(-1))in August,afterwards gradually decreased.Furthermore,the lowest value occurred in October(in daytime 1.55±0.55μmol·m^(-2)·s^(-1),in nighttime 0.81±0.12μmol·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 biva

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 

分 类 号：X171[环境科学与工程—环境科学]