AI 中文总结
研究成熟树木树干温度调控，通过监测多棵树的多种温度及自然电位，发现树干温度有热缓冲，自然电位与温差有延迟关系，最小能量平衡模型表明仅树干蓄热不足，结果显示热-水力耦合对树干热调节有贡献及自然电位可作指标。
AI 中文摘要
树干包含其功能取决于热环境的活组织，但野外条件下控制树干温度的过程仍知之甚少。特别是，水力运输是否有助于缓冲树干温度以抵御大气变化尚不清楚。我们通过连续监测六棵成熟树木（三棵橡树和三棵鹅耳枥）的边材温度、局部气温、1米深处土壤温度和自然电位，研究了这个问题。树干温度的季节性周期比气温更平滑，且更接近深层土壤温度，表明有显著的热缓冲。时间序列提取的季节性成分显示自然电位与树干-土壤温差之间存在连贯的延迟关系。相空间分析显示个体间有可重复的滞后现象。最小能量平衡模型表明仅树干蓄热不足以重现观测到的季节性动态。多数个体获得正的有效土壤耦合系数。这些结果与垂直介导、水力联系的热传递对季节性树干热调节有贡献一致，还表明自然电位可能为树木内缓慢的水力和热过程提供非侵入性综合指标。这种热-水力耦合可能影响形成层和韧皮部的热环境，有助于树木对季节性热量和气候变异性的响应。
英文摘要
Tree trunks contain living tissues whose functioning depends on their thermal environment, yet the processes governing trunk temperature under field conditions remain poorly understood. In particular, it is unclear whether hydraulic transport contributes to buffering trunk temperature against atmospheric variability. We investigated this question by continuously monitoring sapwood temperature, local air temperature, soil temperature at 1~m depth, and spontaneous electrical potential (SP) in six mature trees, comprising three oaks and three hornbeams, over multiple years in a temperate urban forest garden. trunk temperature exhibited a smoother seasonal cycle than air temperature and remained consistently closer to deep-soil temperature, indicating substantial thermal buffering. Seasonal components extracted from the time series revealed a coherent delayed relationship between SP and the trunk-soil temperature difference. Phase-space analysis showed reproducible hysteresis across individuals, and instantaneous phase estimates indicated a lag of approximately 100~days in five of the six trees. A minimal energy-balance model further showed that trunk heat storage alone was insufficient to reproduce the observed seasonal dynamics. Positive effective soil-coupling coefficients were obtained for most individuals, although their magnitude varied markedly among trees. These results are consistent with a contribution of vertically mediated, hydraulically linked heat transfer to seasonal trunk thermal regulation. They further suggest that spontaneous electrical potentials may provide a non-invasive, integrative indicator of slow hydraulic and thermal processes within trees. Such thermo-hydraulic coupling may influence the thermal environment of the cambium and phloem and could therefore contribute to tree responses to seasonal heat and climatic variability.
Comments23 pages, 11 figures
