阴天和晴天对黄河三角洲芦苇湿地净生态系统CO_2交换的影响  

Net ecosystem exchange of CO_2 on sunny and cloudy days over a reed wetland in the Yellow River Delta,China

作　　者：初小静 韩广轩[1] 邢庆会[1,2] 于君宝[1] 吴立新[3] 刘海防[3] 王光美[1] 毛培利[1] 

机构地区：[1]中国科学院烟台海岸带研究所中国科学院海岸带环境过程与生态修复重点实验室,山东烟台264003 [2]中国科学院大学,北京100049 [3]黄河三角洲国家级自然保护区管理局,山东东营257091

出　　处：《植物生态学报》2015年第7期661-673,共13页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(41301083);国家科技支撑计划项目(2011BAC02-B01)

摘　　要：云量以及大气气溶胶含量变化引起的阴天和晴天会对局地的微气候环境产生综合效应,影响地面接收的太阳辐射强度,同时引起环境因子的变化,最终对净生态系统CO2交换(NEE)产生影响。该文通过涡度相关系统以及微气象梯度观测系统,对黄河三角洲芦苇(Phragmites australis)湿地NEE以及环境要素进行了观测。在自然条件下选择12对相邻阴天和晴天数据,在生物要素(生物量、叶面积指数)、土壤水分以及养分特征保持不变的前提下,揭示了阴天和晴天变化对湿地生态系统NEE的光响应和温度响应的影响。结果表明:12对阴天和晴天生态系统NEE的日平均动态均呈"U"型曲线,但阴天NEE的变幅较小。晴天条件下湿地生态系统NEE的日均值显著高于阴天(p<0.01)。阴天和晴天湿地生态系统NEE与光合有效辐射(PAR)之间均呈直角双曲线关系,但晴天条件下,最大光合速率(Amax)显著大于阴天(p<0.01),同时白天生态系统呼吸(Reco,daytime)也显著大于阴天(p<0.01)。不论阴天还是晴天,Reco,daytime与气温均呈显著的指数关系。晴天湿地生态系统呼吸的温度敏感系数Q10(5.5)远大于阴天(1.9)。阴天和晴天昼间PAR差值以及气温差值对NEE差值的协同影响达到63%。Aims Clouds and aerosols change the radiation level on the land surface and indirectly alter the microclimate. Shifts in sunny and cloudy days, for example, would affect the net ecosystem exchange of CO2 （NEE） between land surface and the atmosphere. Our objective was to analyze the influence of shifts in sunny and cloudy days on NEE, its responses to light and temperature in a reed （Phragmites australis） wetland in the Yellow River Delta, China. Methods Using the eddy covariance technique, we measured the temporal changes in NEE during the growing season over the reed wetland. We selected 12 paired-days during the measurement period following two criteria： （1） the two paired days are adjacent, with one sunny day and another cloudy day; （2） no rain event during the two days. We assumed that： （1） live biomass and leaf area index （LAI） are the same during any paired-days; （2） soil moisture has no significant difference between the two adjacent days. With these criteria, we expected that radia- tion condition exerted the major control on NEE. Important findings Diurnal change of NEE showed a distinct U-shaped pattern on both sunny and cloudy days, but with substantial variation in its amplitude. During the daytime, NEE on sunny days was significantly higher （p 〈 0.01） than that on the cloudy days （n = 12）. The daytime NEE response to photosynthetically active radiation （PAR） was modeled with the rectangular hyperbolic function （Eq. （1）） for both sunny and cloudy days. There appeared a significant reduction （p 〈 0.01） in light-saturated NEE （Amax） on cloudy days compared to the sunny days. Similarly, there was a significant decrease （p 〈 0.01） in daytime ecosystem respiration （Reco,daytime） on cloudy days as compared to that of the sunny day although there existed significant exponential relationships between Reco,daytime and air temperature on both sunny and cloudy days. In addition, the temperature sensitivity of ecosys- tem respiration （Q1

关 键 词：阴天 晴天 净生态系统CO2交换 白天生态系统呼吸 光响应 温度响应 

分 类 号：Q948[生物学—植物学]