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张掖灌区玉米农田生态系统CO2通量的变化规律和环境响应

张蕾1,2,3,孙睿1,2,3**,乔晨2,刘绍民1,2,徐自为1,2,唐侥2,郝虑远2,张荣华2   

  1. 1遥感科学国家重点实验室(北京师范大学/中国科学院遥感应用研究所), 北京 100875; 2北京师范大学地理学与遥感科学学院, 北京 100875; 3环境遥感与数字城市北京市重点实验室, 北京 100875)
  • 出版日期:2014-07-10 发布日期:2014-07-10

Variation of CO2 flux and its response to environmental factors in a maize agroecosystem in Zhangye irrigation area.

ZHANG Lei1,2,3, SUN Rui1,2,3**, QIAO Chen2, LIU Shao-min1,2, XU Zi-wei1,2, TANG Yao2, HAO Lü-yuan2, ZHANG Rong-hua2   

  1. (1State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and the Institute of Remote Sensing Applications, CAS, Beijing 100875, China; 2School of Geography and Remote Sensing Sciences, Beijing Normal University, Beijing 100875, China; 3Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, Beijing 100875, China)
  • Online:2014-07-10 Published:2014-07-10

摘要: 采用涡动相关法对张掖灌区玉米农田生态系统生长季(6—9月)CO2通量进行了连续观测,分析了玉米农田生态系统CO2通量变化特征及其对环境的响应。结果表明:CO2通量具有明显的日变化特征,白天以碳吸收为主,夜间以碳排放为主,CO2吸收的最大值出现在灌浆期,峰值为-1.426 mg·m-2·s-1;农田生态系统在4个生育期均表现为碳吸收,但吸收CO2能力存在显著差异,日吸收总量灌浆期>拔节期>成熟期>苗期。利用MichaelisMenten方程和指数曲线拟合方法,分别分析了光合有效辐射对白天CO2通量的影响,及温度对夜间生态系统呼吸的影响。结果表明:白天CO2吸收强度随着光合有效辐射的增大而增大,在低光阶段,光照是控制光合作用的主导因子,之后随着光合有效辐射的增大,净吸收量增加减缓;玉米的光量子利用效率变化范围为0.00098~0.0022 mg·μmol-1。夜间生态系统呼吸与温度呈显著的指数关系,不同生育期的主导因子不同,苗期土壤温度是主导因子,其余生育期气温是主导因子。

关键词: 黑河中游地区, 生态质量, 生态等级, 土地利用转型

Abstract:

CO2 flux was measured continuously in a maize agroecosystem in Zhangye irrigation area during the growing season (June to September) using the eddy covariance technique to study the variation of CO2 flux and its response to key environmental factors. The results showed that there was a distinct diurnal variation of CO2 flux, with CO2 absorption in the daytime and emission at night. The maximum CO2 absorption occurred at filling stage and with a maximum value of -1.426 mg·m-2·s-1. Maize agroecosystem is characterized by carbon absorption during the growing season, and the ability to absorb CO2 is significantly different at different growth stages, which was ordered as filling stage > jointing stage > maturity stage > seedling stage. We also used the MichaelisMenten equation and exponential curve fitting method to analyze the impact of photosynthetically active radiation (PAR) on daytime CO2 flux, and the impact of temperature on the ecosystem respiration at night. The results showed that CO2 absorbing intensity increased with PAR. PAR was the dominant factor to control photosynthesis under low solar radiation, and the carbon assimilation rate increased slowly under high solar radiation. The light quantum efficiency of maize ranged between 0.00098 and 0.0022 mg·μmol-1 during the observing period. The nighttime ecosystem respiration exponentially increased with temperature, and the dominant factor varied with growth stage. Soil temperature was the dominant factor of nighttime ecosystem respiration at the seedling stage, while air temperature was the dominant factor at the other growth stages.
 

Key words: the middle reaches of Heihe River, land use transition, ecological quality, ecological grade