Guo Hui, Li Sien, Wong Fuk-Ling, Qin Shujing, Wang Yahui, Yang Danni, Lam Hon-Ming
Center for Agricultural Water Research in China, China Agricultural University, Beijing, 100083, China.
Center of Soybean Research of the State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China.
Carbon Balance Manag. 2021 Apr 30;16(1):12. doi: 10.1186/s13021-021-00176-5.
Under the escalating threat to sustainable development from the global increase in carbon dioxide concentrations, the variations in carbon flux in the farmland ecosystem and their influencing factors have attracted global attention. Over the past few decades, with the development of eddy covariance technology, the carbon fluxes of farmlands have been determined in many countries. However, studies are very limited for drip irrigation maize the arid regions in northwestern China, which covers a large area where a mixed mode of agriculture and grazing is practiced.
To study the effects of drip irrigation on the net ecosystem productivity (NEE), ecosystem respiration (ER), gross primary production (GPP) and net biome productivity (NBP) in the arid regions of northwestern China, we measured the carbon flux annually from 2014 to 2018 using an eddy covariance system. Our results showed that the maize field carbon flux exhibited single-peak seasonal patterns during the growing seasons. During 2014-2018, the NEE, ER and GPP of the drip-irrigated maize field ranged between - 407 ~ - 729 g C m, 485.46 ~ 975.46 g C m, and 1068.23 ~ 1705.30 g C m. In four of the 5 study years, the ER released back to the atmosphere was just over half of the carbon fixed by photosynthesis. The mean daily NEE, ER and GPP were significantly correlated with the net radiation (Rn), air temperature (Ta), leaf area index (LAI) and soil moisture (SWC). The results of path analysis showed that leaf area index is the main driving force of seasonal variation of carbon flux. When harvested removals were considered, the annual NBP was - 234 g C m, and the drip-irrigated maize field was a carbon source.
This study shows the variation and influencing factors of NEE, ER and GPP in the growth period of spring maize under film drip irrigation in arid areas of northwest China. The ecosystem was a carbon sink before maize harvest, but it was converted into a carbon source considering the carbon emissions after harvest. The variation of carbon flux was influenced by both environmental and vegetation factors, and its leaf area index was the main driver that affects the seasonal variation of carbon flux.
在全球二氧化碳浓度上升对可持续发展构成的威胁不断升级的情况下，农田生态系统中碳通量的变化及其影响因素已引起全球关注。在过去几十年中，随着涡度相关技术的发展，许多国家已测定了农田的碳通量。然而，对于中国西北干旱地区采用农业和放牧混合模式的大面积滴灌玉米的研究非常有限。
为研究滴灌对中国西北干旱地区净生态系统生产力（NEE）、生态系统呼吸（ER）、总初级生产力（GPP）和净生物群系生产力（NBP）的影响，我们在2014年至2018年期间使用涡度相关系统每年测量碳通量。我们的结果表明，玉米田碳通量在生长季节呈现单峰季节性模式。在2014 - 2018年期间，滴灌玉米田的NEE、ER和GPP范围分别为-407至-729 g C m、485.46至975.46 g C m和1068.23至1705.30 g C m。在5个研究年份中的4年，释放回大气的ER仅略高于光合作用固定碳量的一半。日均NEE、ER和GPP与净辐射（Rn）、气温（Ta）、叶面积指数（LAI）和土壤湿度（SWC）显著相关。通径分析结果表明，叶面积指数是碳通量季节变化的主要驱动力。考虑收获移除量时，年NBP为-234 g C m，滴灌玉米田是一个碳源。
本研究展示了中国西北干旱地区膜下滴灌春玉米生长期间NEE、ER和GPP的变化及影响因素。玉米收获前生态系统是碳汇，但考虑收获后的碳排放则转化为碳源。碳通量的变化受环境和植被因素影响，其叶面积指数是影响碳通量季节变化的主要驱动因素。
