Climate change is predicted to cause northward migration of boreal tree species. However, the success of such a migration will be determined by trees’ ability to acclimate to the environmental conditions at the potential new site. This study was aimed to assess the interactive effects of changes in photoperiod associated with northward migration and soil warming on the ecophysiological traits of jack pine (Pinus banksiana Lamb.) under different carbon dioxide concentrations [CO₂]. We examined the responses of foliar gas exchange and seedling cold hardiness after exposing 1-year old seedlings to two [CO₂] (400 and 950 µmol mol⁻¹), two soil temperatures (growing season average at seed origin and 5 °C warmer) and three photoperiod regimes (seed origin, and 5° and 10° further north) for one growing season. We found that the CO₂ elevation significantly increased photosynthetic rate measured at treatment CO₂, photosynthetic water use efficiency, maximum rate of carboxylation and triose phosphate utilization. Some of the effects were modified by photoperiod. Furthermore, the CO₂ elevation and soil warming both reduced seedling cold hardiness, as indicated by increases in injury index. The lack of interactions between photoperiod and other treatments (elevated [CO₂] and soil temperature) suggests that young jack pine seedlings may have the ability to acclimate to the new photoperiod regimes at higher latitudes north of the seed origin.

预计气候变化将导致北方树种向北迁移。但是，这种迁移能否成功取决于树木适应潜在新地点环境条件的能力。这项研究旨在评估在不同二氧化碳浓度[CO ₂ ]下与北移和土壤变暖相关的光周期变化对千斤顶松（Pinus bankiana Lamb。）的生态生理特性的相互作用。在将一岁的幼苗暴露于两种[CO ₂ ]（400和950 µmol mol ^-1）后，我们检查了叶片气体交换和幼苗抗寒性的响应），两个土壤温度（种子起源和温度升高5°C时的生长季节平均值）和三个光周期模式（种子起源，以及距北5°和10°的一个生长季节）。我们发现，CO ₂升高显着提高了在处理CO _2时测得的光合速率，光合用水效率，最大羧化速率和磷酸三糖利用率。一些影响被光周期改变。此外，CO ₂升高和土壤变暖都降低了幼苗的抗寒性，如伤害指数的增加所示。光周期与其他治疗方法之间缺乏相互作用（升高[CO ₂和土壤温度）表明，年轻的千斤顶松树幼苗可能具有适应种子起源北部较高纬度的新光周期条件的能力。