Understanding of the intraspecific variability in the physiological stress response of trees may enable to mitigate the impact of climate change on forest ecosystems in the future. We studied the photosynthetic performance of five silver fir (Abies alba Mill.) provenances originating from climatically distinct localities. The study was performed in the trial plot of the silver fir provenance experiment IUFRO 2005 on two dates: in the early summer and in the late summer. Heat waves and a decrease in water availability occurred between the two measurement dates, allowing us to study the response of the provenances to suboptimal growing conditions. The provenances were evaluated at the level of PSII photochemistry and CO₂ assimilation by measuring photosynthesis-related pigment content, chlorophyll a fluorescence, and gas exchange parameters. Significant climatic clines were confirmed: the photosynthetic performance before and after the stress period increased with the increasing altitude and precipitation at the site of origin. In contrast, photosynthetic performance declined with the increasing temperature and Ellenberg’s quotient of the origin site. We concluded that provenances originating from high altitudes, corresponding well with more humid and colder conditions in Central Europe, showed the greatest photosynthetic performance and were less responsive to moderate heat and drought. This documents inter-population variation in physiological traits, which needs to be considered in setting rules and recommendations for the transfer of forest reproductive materials.

了解树木的生理应激反应中的种内变异性可能有助于减轻气候变化对未来森林生态系统的影响。我们研究了来自气候不同地区的五种冷杉冷杉种源的光合作用性能。这项研究是在银杉种源实验IUFRO 2005的试验区中的两个日期进行的：初夏和夏末。在两个测量日期之间发生了热浪和水供应的减少，这使我们能够研究种源对次优生长条件的响应。在PSII光化学和CO ₂水平上评估了来源通过测量光合作用相关色素含量（叶绿素a）进行同化荧光和气体交换参数。确认了重要的气候变化：胁迫时期之前和之后的光合作用性能随着海拔的升高和起源地的降水增加而增加。相反，随着温度的升高和起源地的Ellenberg商数的增加，光合性能下降。我们得出的结论是，起源于高海拔的种源，与中欧更多的潮湿和寒冷条件相对应，表现出最大的光合性能，对中度高温和干旱的反应较弱。该文件记录了种群间生理特性的差异，在制定有关森林繁殖材料转移的规则和建议时需要加以考虑。