Tree stems are an overlooked source of volatile organic compounds (VOCs). Their contribution to ecosystem processes and total VOC fluxes is not well studied, and assessing it requires better understanding of stem emission dynamics and their driving processes. To gain more mechanistic insight into stem emission patterns, we measured monoterpene, methanol and acetaldehyde emissions from the stems of mature Scots pines (Pinus sylvestris L.) in a boreal forest over three summers. We analysed the effects of temperature, soil water content, tree water status, transpiration and growth on the VOC emissions and used generalized linear models to test their relative importance in explaining the emissions. We show that Scots pine stems are considerable sources of monoterpenes, methanol and acetaldehyde, and their emissions are strongly regulated by temperature. However, even small changes in water availability affected the emission potentials: increased soil water content increased the monoterpene emissions within a day, whereas acetaldehyde and methanol emissions responded within 2–4 days. This lag corresponded to their transport time in the xylem sap from the roots to the stem. Moreover, the emissions of monoterpenes, methanol and acetaldehyde were influenced by the cambial growth rate of the stem with 6–10‐day lags.

中文翻译：

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受树水关系和冈比亚生长影响的苏格兰松（Pinus sylvestris L.）的单萜，乙醛和甲醇的茎排放量。

树茎是挥发性有机化合物（VOC）的一个被忽视的来源。它们对生态系统过程和总VOC通量的贡献还没有得到很好的研究，对其进行评估需要对茎排放动力学及其驱动过程有更好的了解。为了更深入地了解茎排放模式，我们测量了成熟苏格兰松树（Pinus sylvestris）茎中的单萜，甲醇和乙醛排放量。L.）在三个夏天的北方森林中。我们分析了温度，土壤含水量，树木水状态，蒸腾作用和生长对VOC排放的影响，并使用广义线性模型检验了它们在解释排放中的相对重要性。我们表明，苏格兰松树茎是单萜，甲醇和乙醛的重要来源，其排放量受温度的强烈调节。但是，即使是可用水量的微小变化也会影响排放潜力：增加土壤水分会在一天之内增加单萜的排放，而乙醛和甲醇的排放会在2-4天之内做出响应。该滞后时间对应于它们在木质部汁液中从根到茎的转运时间。而且，单萜的排放