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为了研究温带落叶阔叶林CO2浓度(摩尔分数,[CO2])的时空变化特征,利用帽儿山通量塔8层[CO2]廓线系统分析了[CO2]的时间动态及垂直梯度,并结合森林小气候的同步测定数据探讨了影响[CO2]时空变化的因子。结果表明:帽儿山温带落叶阔叶林的[CO2]及其垂直梯度具有明显的日变化和季节变化。在日尺度上,[CO2]呈“单峰”曲线,在夜间或日出前后出现最大值,日出后迅速降低,在午后达到最低值,日落时分又开始迅速升高。在季节尺度上,生长季的[CO2]日变幅明显大于非生长季,且冬季(1、2和12月)白天呈“V”型,其他季节白天呈“U”型,这与白天对流边界层的持续时间随季节的变化趋势一致。在垂直方向上,[CO2]及其日变幅随高度增加而降低,并且在生长季夜间湍流交换较弱时其垂直梯度最显著;植被冠层的光合作用改变了生长旺季白天的[CO2]垂直格局,使冠层高度的[CO2]最低;休眠季节该垂直梯度大大减弱。近地层日均[CO2]与土壤温度的趋势相似,呈单峰曲线;而林冠上[CO2]在5月初和10月各出现一次峰值,最低值出现在8月初,与植被光合作用紧密相关。日尺度上[CO2]及其垂直梯度主要受控于大气边界层和生态系统碳代谢过程;年尺度上近地层[CO2]主要受控于土壤呼吸,而林冠上的[CO2]则受生态系统光合作用和呼吸作用的共同控制。
In order to study the spatiotemporal variation of CO2 concentration (molar fraction, [CO2]) in temperate deciduous broad-leaved forests, the temporal dynamics and vertical gradient of [CO2] Combined with the simultaneous determination of forest microclimate data to explore the impact of [CO2] spatio-temporal changes in the factor. The results showed that the [CO2] and its vertical gradient of temperate deciduous broad-leaved forest in Maoershan had obvious diurnal and seasonal variations. On the daily scale, [CO2] showed a “single peak” curve with maximum at night or before sunrise, rapidly decreasing after sunrise, reaching its lowest value in the afternoon and rising rapidly at sunset. On the seasonal scale, the daily variation of [CO2] in the growing season was significantly larger than that in the non-growing season, and in the winter (January, January and December) was “V” and in the other seasons was “U” This is consistent with the changing trend of the duration of daytime convective boundary layer with the seasons. In the vertical direction, [CO2] and its daily amplitude decreased with increasing height, and the vertical gradient was the most significant when turbulent exchange was weak during the growing season. The photosynthesis of vegetation canopy changed the [CO2] during the growing season, The vertical pattern minimizes the canopy height [CO2]; this vertical gradient is significantly reduced during the dormancy season. The daily average [CO2] of the near-surface layer is similar to the trend of soil temperature and shows a single peak curve, while the top of the canopy [CO2] shows a peak in early May and October, with the lowest value occurring in early August, closely related to photosynthesis. On the daily scale, [CO2] and its vertical gradient are mainly controlled by atmospheric carbon sequestration in the atmospheric boundary layer and ecosystem; [CO2] at the annual scale is mainly controlled by soil respiration, while [CO2] at the canopy is affected by the ecosystem Common control of photosynthesis and respiration.