Macroclimatic changes are expected to radically alter coastal wetland ecosystems in the coming century. The trajectory of the response to climate warming may differ based on other concomitantly changing abiotic variables such as soil salinity and relative humidity. Thus, understanding plant responses to multiple interacting stressors is required to accurately predict coastal wetland shifts under climate change. The ongoing poleward shift of mangrove range limits has been linked with a reduction in freeze events, yet interactions between low temperature and other abiotic stressors remain underexplored. We grew two common mangroves (Avicennia germinans and Rhizophora mangle, n = 1222) from propagules for 10 months in environmental growth chambers under experimentally manipulated temperature, salinity, and relative humidity treatments that reflected the range of conditions these species experience in the field. We measured variation in growth and physiological characteristics before, during, and after low temperature exposure. For both species, resistance and resilience to low temperature stress were mediated by salinity and relative humidity conditions. Chronic chilling at 10 °C caused widespread reduction in seedling stem elongation rate, altered leaf gas exchange rates, and increased mortality, particularly under high salinity and low humidity conditions. Additional exposure to an overnight freeze (−4 °C) had relatively minor impacts. Five months after exposure to low temperatures, some R. mangle exhibited the capacity to recover from severe cold damage, but only under optimal humidity and salinity conditions. Although A. germinans were generally more resistant to low temperature stress, severely damaged plants did not recover, even in low salinity and high humidity conditions. We contend that current and future mangrove range limits are the result of interactions between multiple abiotic stressors including temperature, salinity, and relative humidity. Consequently, future modelling approaches to predicting range shifts under climate change need to consider multiple concomitantly changing abiotic variables and their interactions.

预计在未来的世纪中，宏观气候变化将彻底改变沿海湿地生态系统。基于其他伴随变化的非生物变量，例如土壤盐度和相对湿度，对气候变暖的响应轨迹可能会有所不同。因此，需要了解植物对多种相互作用胁迫源的反应，才能准确预测气候变化下的沿海湿地变化。红树林范围极限的不断极移与冻结事件的减少有关，但低温与其他非生物胁迫源之间的相互作用仍未得到充分研究。我们种植了两种常见的红树林（Avicennia Germinans和Rhizophora mangle，n = 1222），通过在环境生长室中经过实验控制的温度，盐度和相对湿度处理的繁殖体进行10个月的繁殖，反映了这些物种在野外所经历的条件范围。我们测量了低温暴露之前，之中和之后生长和生理特征的变化。对于这两个物种，盐度和相对湿度条件都介导了对低温胁迫的抗性和韧性。10°C的长期低温导致幼苗茎伸长率大大降低，叶片气体交换率改变，死亡率增加，特别是在高盐度和低湿度条件下。额外暴露于过夜冻结（−4°C）的影响相对较小。暴露于低温五个月后，R. mangle表现出能够从严重的冷害中恢复的能力，但只能在最佳湿度和盐度条件下才能恢复。尽管一般对低温胁迫的抵抗力为A.，但即使在低盐度和高湿度条件下，严重受损的植物也无法恢复。我们认为当前和未来的红树林范围限制是多种非生物胁迫源（包括温度，盐度和相对湿度）之间相互作用的结果。因此，未来的预测气候变化范围变化的建模方法需要考虑多个伴随变化的非生物变量及其相互作用。