黄河三角洲芦苇湿地生态系统碳通量动态特征及其影响因素

Dynamic Characteristics and Influencing Factors of Carbon and Water Flux in Reed Wetland Ecosystem in the Yellow River Delta

利用涡度相关法,对黄河三角洲芦苇湿地生态系统进行了连续2年的通量观测,分析了2017-2018年生长季芦苇湿地生态系统碳交换量(NEE)及其影响因素,为区域的碳收支预算和为全球碳循环模型的进一步完善提供理论基础。结果表明,在季节尺度上,芦苇湿地生长季具有明显的碳汇功能,生态系统呼吸(R_(s))随着月份的增加呈倒“V”型变化特征,在8月达到最高;生态系统碳交换(NEE)和生态系统总初级生产力(GPP)随着月份的增加呈“V”型变化特征。2018年不同月份生态系统碳交换(NEE)、生态系统总初级生产力(GPP)、生态系统呼吸(R_(s))均高于2017年,局部有所差异,其变化趋势与2017年总体保持一致。在日尺度上,2017-2018年芦苇湿地NEE日变化特征表现为两个CO_(2)吸收高峰,分别出现在11:00和16:00左右,其特点是在午间出现了碳交换通量的降低,CO_(2)排放的日最大值两个生长季均出现在8月。2017-2018年NEE_(night)随着月份的增加呈倒“V”型变化特征,在8月达到最高;而NEE_(total)和NEE_(day)随着月份的增加呈“V”型变化特征,在8月达到最高,局部有所差异。芦苇湿地生态系统的CO_(2)交换受到光合有效辐射(PAR)、土壤温度(t_(s))和土壤体积含水量(T_(a))的共同影响,生长季NEE通量与5 cm土壤温度和土壤湿度呈显著或极显著的指数关系(P<0.05,P<0.01),同时生长季NEE通量与5 cm土壤温度和土壤湿度的R^(2)均高于NEE通量与10 cm土壤温度和土壤湿度的R^(2),由此说明5 cm土壤温度和湿度能够更好的指示NEE通量的变化。

By using the vorticity correlation method,the flux of reed wetland ecosystem in the Yellow River delta was observed for two consecutive years,and the carbon exchange capacity(NEE)of reed wetland ecosystem in the growing season of 2017‒2018 and its influencing factors were analyzed.The results showed that,on the seasonal scale,reed wetland had obvious carbon sink function in the growing season,and the ecosystem respiration(R_(s))showed an inverted“V”shape with the increase of months,reaching the highest in August.Ecosystem carbon exchange(NEE)and ecosystem total primary productivity(GPP)showed a v-shaped change with the increase of the month,reaching the highest level in August.Ecosystem carbon exchange(NEE),total primary productivity(GPP)and ecosystem respiration(R_(s))in different months in 2018 were all higher than that in 2017,with partial differences,and the change trend was generally consistent with that in 2017.On the daily scale,the NEE diurnal change of reed wetland in 2017‒2018 is characterized by two CO_(2) absorption peaks,which appear at about 11:00 and 16:00 respectively.The characteristics are that the carbon exchange flux decreases at noon,and the maximum daily CO_(2) emission occurs in August in both growing seasons.In 2017,with the increase of months,NEEnight showed an inverted“V”shape,reaching the highest in August.The NEE_(total) and NEE_(day) show a v-shaped change with the increase of months,and reach the highest in August.In 2018,NEE_(night),NEE_(total) and NEE_(day) in different months were all higher than that in 2017,with local differences,and the trend was consistent with that in 2017.Reed wetland ecosystem CO_(2) exchange by photosynthetic active radiation(PAR),soil temperature(t_(s))and soil volumetric water content(T_(a))from the combined impact of the growing season NEE flux with 5 cm soil temperature and soil moisture were significantly or extremely significantly relationship between index(P<0.05,P<0.01),at the same time,the growing season NEE flux with 5 cm soil temperature and soil moisture R^(2) were higher than NEE flux and 10 cm soil temperature and soil moisture of R^(2),so 5 cm soil temperature and humidity can better instructions NEE flux changes.