摘要
研究土壤呼吸和温度敏感性(Q_(10))的季节变化对丰富农田土壤的碳循环理论具有重要理论和现实意义。采用动态密闭气室法于2018年6月-2019年6月连续监测北京夏玉米-冬小麦轮作期间农田土壤呼吸速率,研究不同作物生育期Q_(10)值和土壤呼吸变化特征,综合分析土壤温度和土壤含水率对土壤呼吸的影响。结果表明:日内尺度上不同作物生育期土壤呼吸变化均呈单峰型,对土壤温度昼夜变化的响应关系呈顺时针近椭圆曲线;Q_(10)具有明显的季节变化特征,夏玉米苗期、拔节-抽雄、开花-成熟3个时期Q_(10)分别为2.27、6.13、1.28,在整个夏玉米季,土壤体积含水率在19.52%~45.43%变化,水分解释了50%的土壤呼吸变化(P<0.05),临界值土壤体积含水率为27.84%(田间持水量的83.83%),土壤温度只能解释夏玉米季土壤呼吸速率变化的3%(P>0.05),Q_(10)为1.29。冬小麦出苗-分蘖期、越冬期、返青-拔节期、孕穗-抽穗期、开花-成熟期Q_(10)分别为4.17、8.41、6.57、2.53、1.92,与土壤温度呈显著负相关关系(P<0.05),温度能够解释冬小麦季土壤呼吸变化的88%(P<0.01),Q_(10)为2.50。在整个轮作周年,土壤温度和土壤含水率分别解释54%(P<0.01)、28%(P<0.05)的土壤呼吸变化,周年尺度的Q_(10)为1.72。可见,在气候变化背景下,使用Q_(10)预测土壤呼吸需采用合适的时间尺度,同时注意土壤水分对Q_(10)模型适用性的影响。
The temperature sensitivity of soil respiration(Q10)is often used in exponential models to predict or interpolate soil respiration(RS).However,beyond temperature,Q10 can be influenced by factors such as soil water content,substrate availability and microbial activity,so that Q10 may vary with seasonally fluctuating conditions and processes,and differences between Q10 derived from different time scales may exist.In order to understand the variation of RS and Q10 on croplands soils,RS was measured continuously for half an hour by a multichannel automatic soil CO2 efflux system(Li-8150,USA)in a summer maize-winter wheat double cropping system from June 2018 to June 2019 in Beijing suburb.Summer maize growth season was divided into three stages(2018-06-22—2018-07-15,2018-07-16—2018-08-15,2018-08-16—2018-09-17),and winter wheat growth season were decomposed into five stages(2018-10-01—2018-11-22,2018-11-23—2019-02-25,2018-02-26—2019-04-10,2019-04-11—2019-05-13,2019-05-14—2019-06-17)according to the phenology.Seasonal variation of RS and Q10 values at different crop growth stages were studied,respectively,and their responses to the influence factors including soil temperature at 5 cm depth,soil water content,leaf area index and aboveground biomass were analyzed in this article.Moreover,diurnal dynamics of soil respiration rate at different growth state were calculated.The main results are showed as follow:(1)the diurnal variation of the soil respiration rates in different growth stages appeared as a single-peak curve as well as the soil temperature.But soil temperature often peaked later than the half-hourly soil respiration rates at the wheat growth season.The lag time of soil temperature for each growth stages were 4.5,5.0,5.0,2.5,0.5 h.The relationships between diurnal RS and soil temperature showed a clockwise nearly elliptic curve.(2)Q10 exhibited a strong seasonal variation.At seedling,jointing to tasseling,and flowering to mature stage of summer maize,Q10 values were 2.27,6.13 and 1.28 respective
作者
卢闯
胡海棠
淮贺举
程成
田宇杰
李存军
LU Chuang;HU Hai-tang;HUAI He-ju;CHENG Cheng;TIAN Yu-jie;LI Cun-jun(Beijing Research Center for Information Technology in Agriculture,Beijing 100097,China)
出处
《中国农业气象》
CSCD
北大核心
2020年第7期403-412,共10页
Chinese Journal of Agrometeorology
基金
国家重点研发专项计划(2016YFD0700303)
农业部基础性长期监测任务(ZX03S0101)。
