稻油两熟农田生态系统净碳交换特征及其主要影响因子研究北大核心CSCD

为深入了解农田生态系统碳交换规律以及碳循环的机理和过程,本研究采用涡度相关技术,对湘中地区稻油两熟农田生态系统进行了全年的通量观测,分析了碳通量及其各组分在不同时间尺度上的变化特征,探讨了水稻、油菜生长季内碳通量对主要环境因子的响应。结果表明:稻油两熟农田生态系统净碳交换日尺度变化特征总体呈"U"型单峰曲线变化,季节变化特征呈现单峰双谷"W"曲线变化,存在两个明显的碳吸收期;净碳交换吸收峰值水稻普遍高于油菜,总初级生产力和生态系统呼吸的累积速率水稻高于油菜;稻油两熟农田生态系统全年的净碳交换累积总量为-206.26 g/m^(2),总初级生产力累积总量为1 173.9 g/m^(2),生态系统总呼吸累积总量为967.64 g/m^(2),生态系统的碳利用效率为17.6%,总体表现为碳吸收旺盛;水稻和油菜生长季内碳通量与环境因子的相关性不同,白天的净碳交换与光合有效辐射呈负相关,夜间生态系统呼吸随土壤温度的升高呈指数曲线变化,油菜的温度敏感性要高于水稻。本研究结果可为农田固碳减排提供理论依据和数据支持。

Characteristics of net carbon exchange and its main influencing factors in rice-oilseed rape double cropping farmland ecosystem

In order to understand the carbon exchange patterns and carbon cycling mechanisms of farmland ecosystems, this study used eddy covariance method to observe the fluxes of rice-oilseed rape double cropping farmland ecosystems in central Hunan Province throughout the year, and analyzed the changes of carbon fluxes and their components at different time scales, and explored the responses of carbon fluxes to major environmental factors during the growing seasons of rice and oilseed rape. The results showed that the daily variation of net carbon exchange in rice-oilseed rape double cropping farmland ecosystems showed a "U" type single-peak curve, and the seasonal variation showed a single-peak double-valley "W" curve, and there were two obvious carbon uptake periods. The peak of NEE uptake was generally higher in rice than in rape and the accumulation rate of GPP and Reco was higher in rice than in oilseed rape; the total accumulation of net carbon exchange was -206.26 g/m2, the total accumulation of total primary productivity was 1 173.9 g/m2, the total accumulation of ecosystem respiration was 967.64 g/m2, and the carbon use efficiency of the ecosystem was 17.6%, which generally showed that carbon uptake was strong. The correlation between carbon fluxes and environmental factors was different between rice and oilseed rape during the growing season, and the net carbon exchange during daytime was negatively correlated with photosynthetic effective radiation. The results of this study can provide theoretical basis and data support for carbon sequestration and emission reduction in farmland.