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中国北方针叶林碳通量动态变化及其影响因素分析

Dynamic Changes in Carbon Fluxes of the Boreal Coniferous Forests of China and Influencing Factor Analysis

  • 摘要: 基于北方针叶林典型站点——呼中定位观测站2014~2018年不同时间尺度碳通量观测数据,探究了该生态系统长时间序列碳通量动态变化及其影响因素。结果表明:受总初级生产力(Gross Primary Productivity, GPP)和生态系统呼吸(Ecosystem Respiration, RE)的综合作用影响,北方针叶林生态系统净碳交换量(Net Ecosystem Exchange, NEE)年际变化差异较大,在2.64~17.63 g(C) m−2 a−1之间波动;从季节上看,在生长季(6~8月)GPP值大于RE,北方针叶林以净碳吸收为主,在非生长季,NEE与RE相等,北方针叶林为弱碳源;逐日尺度上,NEE呈倒“U”形变化特征,RE和GPP则呈“U”形特征。日尺度NEE主要受净辐射、相对湿度、气温、土壤温度等因素影响,这些环境因素构建的回归方程可以解释45.19%的NEE日变化;月尺度上NEE主要受净辐射、相对湿度、气温3个因素影响,回归方程可以解释78.42%的NEE月变化。

     

    Abstract: The long-term temporal dynamics of carbon fluxes and their influencing factors in this ecosystem investigated by utilizing observational data collected from the Huzhong Positioning Observatory, located at a typical site in boreal coniferous forests in China from 2014 to 2018. The results indicate that the Net Ecosystem Exchange (NEE) in boreal coniferous forests exhibits significant interannual variability, ranging between 2.64 g(C) m−2 a−1 and 17.63 g(C) m−2 a−1. This variability is attributed to the interplay of Gross Primary Productivity (GPP) and Ecosystem Respiration (RE). The results also reveal that during the growing season (June–August), GPP exceeds RE, leading to net carbon absorption in the forests. Meanwhile, during the nongrowing season, NEE equals RE, positioning boreal coniferous forests as weak carbon sources. At the daily scale, the trend of NEE variation exhibits an inverted “U” shape, while those of RE and GPP show a “U” shape. The study identifies key factors such as Net Radiation (RN), Relative Humidity (RH), Air Temperature (TA), and Soil Temperature (TS) as primary influencers of daily NEE variations. A regression equation incorporating these environmental factors accounts for 45.19% of the daily NEE variations. At the monthly scale, NEE is primarily influenced by RN, RH, and TA. A regression equation incorporating these environmental factors accounts for 78.42% of the monthly NEE variations.

     

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