In this study, we developed a three-way carbon dioxide (CO₂) flux-partitioning algorithm that separates net ecosystem exchange (NEE) into aboveground plant respiration (R_above), belowground root and soil respiration (R_below), and gross primary production (GPP). We applied this algorithm to a coupled dataset of continuous chamber-measured soil respiration and eddy covariance (EC)-measured NEE of CO₂ in an oak-hickory (Quercus-Carya) deciduous broadleaf forest from 2006 to 2015. We found that on annual time scale, R_below dominated over R_above with the former accounting for 66.9–86.4% and the latter 13.6–33.1%, of the total ecosystem respiration (R_eco). The ratio of R_below to R_above varied seasonally, ranging from 1.77 to 7.25 in growing season, and 1.02 to 4.57 in non-growing season. The temperature sensitivity (E₀) of R_below was significantly higher than that of R_above, and E₀ of R_eco responded differently to air and soil temperature. Over the whole study period, annual mean R_above, R_below, and GPP were 243, 806, and 1170 g C m⁻², respectively, with annual R_eco accounting for 89.6% of GPP, of which 68.8% was lost as R_below and 20.8% lost as R_above, and leaving only 10% of the carbon fixation in ecosystems. These estimates, however, did not consider potential light inhibition of leaf respiration. If we accept the presence of light inhibition, then the daytime three-way partitioning method would underestimate annual R_above by 20.4% whereas the nighttime method would overestimate R_above by 23.9% and GPP by 4.7%, compared with estimates accounting for light inhibition in leaves.

在这项研究中，我们开发了一种三向二氧化碳 (CO ₂ ) 通量分配算法，将净生态系统交换 (NEE) 分为地上植物呼吸 (R _above )、地下根和土壤呼吸 (R _below ) 以及总初级生产（GPP）。我们将该算法应用于2006 年至 2015 年橡树山核桃 ( Quercus-Carya ) 落叶阔叶林中连续室测量的土壤呼吸和涡度协方差 (EC) 测量的 CO ₂ NEE 的耦合数据集。我们发现，每年时间尺度上，R_低于R_高于R_高于R _，前者占生态系统总呼吸的66.9-86.4%，后者占13.6-33.1%（R_生态）。R_低于与R_高于的比值随季节变化，生长季节为1.77～7.25，非生长季节为1.02～4.57。R _below的温度敏感性（E ₀）显着高于R _above，并且R _{eco 的}E ₀对空气和土壤温度的响应不同。在整个研究期间，年平均R_高于、R_低于和GPP分别为243、806和1170 g C m ^-2，年R _eco占GPP的89.6%，其中68.8%作为R损失_以下和 20.8%_以上的R 损失，仅留下 10% 的碳固定在生态系统中。然而，这些估计没有考虑叶呼吸的潜在光抑制。如果我们接受光抑制的存在，那么与考虑光抑制的估计值相比，白天三向分区方法将低估年 R_以上20.4%，而夜间方法将高估 R_以上23.9% 和 GPP 4.7%树叶。