湘中地区冬油菜全生育期碳通量变化特征分析

Variation characteristics of carbon flux during the whole growth period of winter rapeseed in central Hunan Province

为探讨冬油菜的净碳交换特征及其固碳能力,采用涡度相关法对湘中地区油菜生态系统(2019年10月-2020年5月)的碳通量进行连续观测,分析了油菜全生育期内碳通量变化特征。结果表明:油菜生育期内碳通量具有明显的日变化和季节变化动态,碳通量月平均日变化以及不同生育期日变化均呈现为夜间高、白天低、正午达到最低谷的“U”型单峰曲线变化,不同月份和不同生育期的差异主要体现在曲线变化的幅度上;油菜不同生育时期的固碳能力有所不同,固碳能力由大到小依次为:花期、角果期、抽薹期、苗期,固碳能力总体随生育进程推进不断提升;油菜生育期内的净碳交换量总和为-101.62 gC·m^(-2)、总初级生产力为461.67 gC·m^(-2)、总呼吸为360.05 gC·m^(-2),即净CO_(2)吸收量为1.02 t·hm^(-2),说明油菜生态系统表现出一定的碳汇功能。

In order to explore the net carbon exchange characteristics and carbon sequestration capacity of winter rapeseed,vorticity correlation method was used to continuously observe the carbon flux of rapeseed ecosystem in central Hunan Province from October 2019 to May 2020.Variation characteristics of carbon flux during the whole growth period of rapeseed were also analyzed.Results showed that the carbon flux had obvious diurnal and seasonal variations during rapeseed growth.The monthly average diurnal variation of carbon flux and the diurnal variation of different growth stages showed a"U"shaped unimodal curve,which was high at night,low in the day and reached the lowest point at noon.The difference between different months and different growth stages was mainly reflected in the range of curve change.The carbon sequestration capacity of rapeseed was different in different growth stages,and the order of carbon sequestration was in:flowering stage,pod stage,bolting stage,and seedling stage.The carbon sequestration capacity generally increased with the growth process.The total net ecosystem exchange,gross primary productivity and ecosystem respiration were -101.62 gC·m^(-2),461.67 gC·m^(-2) and 360.05 gC·m^(-2) respectively.Net CO_(2) uptake was 1.02 t·hm^(-2).These results indicated that the rapeseed ecosystem showed a certain carbon sink function.