中文摘要：

树干CO2释放通量（Es）是森林生态系统碳收支的重要组分,但是目前对Es的季节动态和树种间差异的调控认识不足。该文采用红外气体分析法于2013年7–10月和2014年3–7月原位测定了东北温带森林中4个针叶树种（红松（Pinus koraiensis）、红皮云杉（Picea koraiensis）、樟子松（Pinus sylvestris var.mongolica）和落叶松（又名兴安落叶松）（Larix gmelinii））的Es、树干温度（Ts）等因子,旨在比较分析Es的季节动态和树种间差异及其驱动因子。结果发现：整个测定期间4个树种Es的时间动态总体上与Ts变化一致,高峰值出现在温度较高和生长迅速的夏季（5月末–7月初）,最小值则出现在温度较低的春季（3月末–4月末）或秋季（10月）。Ts分别解释了所有树种生长季（5–9月）和非生长季（其他月份）Es变异性的42%–91%和56%–89%。进一步分析发现,除了Ts之外,生长季期间4个树种的Es与日胸围生长量、樟子松和落叶松的Es与空气相对湿度、樟子松的Es与边材氮浓度也显著相关。这些结果表明Ts是影响Es的主导环境因子,但影响程度随树种、生长节律变化而变化。同一树种生长季的Es显著高于非生长季,而同一季节不同树种之间Es差异显著。生长季不同树种Es的温度系数（Q10值）的差异不显著（波动在1.64–2.09之间）,但在非生长季却存在显著性差异（波动在1.80–3.14之间）;并且红皮云杉、樟子松和落叶松生长季的Q10值均显著低于非生长季,说明不同树种Es对温度变化响应的差异主要表现在非生长季。上述这些温带针叶树Es的季节和种间变化受温度等多因子联合驱动,因此采用单一的Es温度响应方程会增大Es年通量估测的不确定性。

英文摘要：

Aims Stem CO2 effiux （Es） is an important component of annual carbon budget in forest ecosystems, but how biotic and environmental factors regulate seasonal and inter-specific variations in Es is poorly understood. The objectives of this study were： （1） to compare seasonal dynamics in Es for four temperate coniferous tree species in northeastem China, including Korean pine （Pinus koraiensis）, Korean spruce （Picea koraiensis）, Mongolian pine （Pinus sylvestris var. mongolica）, and Dahurian larch （Larix gmelinii）; and （2） to explore factors driving the inter-specific variability in Es during the growing and non-growing seasons. Methods Ten to twelve trees for each tree species were sampled for Es and stem temperature at 1 cm depth be- neath the bark （Ts） measurements in situ with an infrared gas analyzer （LI-6400 IRGA） and a digital thermometer, respectively, from July to October 2013 and March to July 2014. The daily stem circumference increment （Si）, sapwood nitrogen concentration （[N]）, and related environmental factors were monitored simultaneously. Important findings The temporal variation in Es for the four tree species overall followed the changes in Ts throughout the study period, with the maxima occurring in the summer months （late May to early July） character- ized by higher temperature and more rapid stem growth and the minima in spring （late March to April） or autumn （October） having lower temperature. Ts accounted for 42%-91% and 56%-89% of variations in Es during the growing （May to September） and non-growing （other months） seasons, respectively. Furthermore, apart from Ts, we also found significant regression relationships between Es and Si, relative air humidity and [N] during the growing season, but their forms and correlation coefficients were species-dependent. These results indicated that Ts was the dominant environmental factor affecting seasonal variations in Es, but the magnitude of the effect var- ied with tree species and grow