We conducted a four-year in situ experiment using chamber, eddy covariance, and mass spectrometry methods to partition nocturnal respiratory components (F_r, ecosystem respiration; F_rs, soil respiration; F_rsh, heterotrophic respiration; F_raa and F_rab, above and below ground autotrophic respirations) and their respective carbon isotopic signatures (δ_r, δ_rs, δ_rsh, δ_raa, and δ_rab) in a wheat–maize rotation in the North China Plain. The annual patterns in F_r, F_rs, F_raa, and F_rab showed a bimodal curve in response to plant development, nitrogen fertilization, irrigation and precipitation events. F_rs, F_rsh, F_raa and F_rab accounted for 43.4, 13.5, 56.6 and 29.9 % of F_r in the wheat season and 34.0, 15.2, 66.0 and 18.8 % of F_r in the maize season, respectively. The annual values of F_r, F_rs, F_rsh, F_raa, and F_rab in the maize season were 2.18, 1.71, 2.45, 2.54, and 1.37 times those in the wheat season, respectively. In comparison, the annual values of δ_r, δ_rs, δ_rsh, δ_raa, and δ_rab in the wheat season were 5.84, 10.4, 9.84, 9.63, and 11.6 % more depleted than those in the maize season, respectively. The δ_raa and δ_rab means in the wheat (C₃) season significantly depleted than those in the maize (C₄) season due to the different photosynthetic carbon metabolisms in the two systems. Hysteretic response (2-3 hours) where soil temperature leads soil respiration was found, suggesting a causal role of temperature in the relationship. Higher soil temperature and water filled pore space (≥ 50 %) depleted δ¹³CO₂ signatures. Overall, this study revealed the carbon balance of nocturnal respiratory components and their respective δ¹³CO₂ signatures in a wheat-maize rotation.

我们使用腔室、涡流协方差和质谱法进行了为期四年的原位实验，以划分夜间呼吸成分（F _r，生态系统呼吸；F _rs，土壤呼吸；F _rsh，异养呼吸；F _raa和 F _rab，上述和地下自养呼吸）及其各自的碳同位素特征（δ _r、δ _rs、δ _rsh、δ _raa和 δ _rab）在华北平原的小麦-玉米轮作中。F _r、 F _rs、 F _raa和 F 中的年度模式_rab显示出响应植物发育、施氮、灌溉和降水事件的双峰曲线。F _rs、F _rsh、F _raa和F _rab在小麦季节分别占F _{r 的43.4、13.5、56.6}和29.9 %，在玉米季节分别占F _{r 的}34.0、15.2、66.0和18.8 % 。F _r、F _rs、F _rsh、F _raa和F _rab在玉米季的年值分别是小麦季的_{2.18、1.71、2.45、2.54}和1.37倍。相比之下，δ _r、δ _rs、δ的年值小麦季节的_rsh、δ _raa和δ _{rab 的消耗量}分别比玉米季节高_{5.84、10.4、9.84、9.63}和 11.6%。由于两个系统光合碳代谢不同，小麦（C ₃）季节的δ _raa和δ _rab均比玉米（C ₄）季节显着减少。发现土壤温度导致土壤呼吸的滞后反应（2-3 小时），表明温度在关系中具有因果作用。较高的土壤温度和充满水的孔隙空间 (≥ 50 %) 消耗了 δ ¹³ CO ₂签名。总体而言，该研究揭示了小麦-玉米轮作中夜间呼吸成分的碳平衡及其各自的 δ ¹³ CO ₂特征。