The physiological cold tolerance of warm-climate plants is correlated with their latitudinal range limit

Plants are moving poleward and upward in response to climate warming. However, such movements lag behind the expanding warming front for many reasons, including the impediment of plant movement caused by unusual cold events. In this study, we measured the maximum photochemical efficiency of PSII (Fv/Fm) in 101 warm-climate angiosperm species to assess their cold tolerance at the end of a severe chilling period of 49 days in a southern subtropical region (Nanning) in China. We found that 36 of the 101 species suffered from chilling-induced physiological injury, with predawn Fv/Fm values < 0.7. There was a significant exponential relationship between the predawn Fv/Fm and northern latitudinal limit of a species; species with a lower latitudinal limit suffered more. Our results suggest that the range limits of warm-climate plants are potentially influenced by their physiological sensitivity to chilling temperatures and that their poleward movement might be impeded by extreme cold events...

为应对气候变暖，植物正向极地迁移、向高海拔扩张。然而这类迁移滞后于升温前沿的扩张，背后存在多重诱因，其中便包括极端低温事件对植物迁移造成的阻碍。本研究于中国南部亚热带区域（南宁），在为期49天的强低温胁迫期结束之际，针对101种暖气候被子植物（angiosperm）测定了其光系统II（PSII）的最大光化学效率（Fv/Fm），以此评估它们的耐寒性。研究结果显示，101个物种中有36种出现了低温诱导的生理损伤，其黎明前Fv/Fm值低于0.7。物种的黎明前Fv/Fm值与其分布的北部纬度极限之间存在显著的指数相关关系：分布纬度下限更低的物种，受低温胁迫的损伤程度越重。本研究结果表明，暖气候植物的分布范围极限可能受其对低温的生理敏感性影响，而极端低温事件或会阻碍其向极地的迁移进程……