In tundra ecosystems, snow cover protects plants from low temperatures in winter and buffers temperature fluctuations in spring. Climate change may lead to reduced snowfall and earlier snowmelt, potentially exposing plants to more frequent and more severe frosts in the future. Frost can cause cell damage and, in combination with high solar irradiance, reduce the photochemical yield of photosystem II (ΦPSII). Little is known about the natural variation in frost exposure within individual habitats of tundra plant populations and the populations’ resilience to this climatic variation. Here, we assessed how natural differences in snowmelt timing affect microclimatic variability of frost exposure in habitats of the evergreen Vaccinium vitis-idaea in sub-Arctic alpine Finland and whether this variability affects the extent of cell damage and reduction in ΦPSII. Plants in early melting plots were exposed to more frequent and more severe frost events, and exhibited a more pronounced decrease in ΦPSII, during winter and spring compared to plants in late-melting plots. Snowmelt timing did not have a clear effect on the degree of cell damage as assessed by relative electrolyte leakage. Our results show that sub-Arctic alpine V. vitis-idaea is currently exposed to strong climatic variation on a small spatial scale, similar to that projected to be caused by climate change, without significant resultant damage. We conclude that V. vitis-idaea is effective in mitigating the effects of large variations in frost exposure caused by differences in snowmelt timing. This suggests that V. vitis-idaea will be resilient to the ongoing climate change.

中文翻译：

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亚北极高山越橘对融雪时间和霜冻暴露的强烈变化具有抵抗力，表明在气候变化下具有高弹性

在苔原生态系统中，积雪可以保护植物在冬季免受低温影响，并在春季缓冲温度波动。气候变化可能导致降雪量减少和融雪提前，未来可能使植物面临更频繁、更严重的霜冻。霜冻会导致细胞损坏，并且与高太阳辐照度相结合，会降低光系统 II (ΦPSII) 的光化学产率。关于苔原植物种群个体栖息地内霜冻暴露的自然变化以及种群对这种气候变化的适应能力知之甚少。这里，我们评估了融雪时间的自然差异如何影响亚北极高山芬兰常绿牛痘栖息地中霜冻暴露的微气候变异性，以及这种变异性是否影响细胞损伤的程度和 ΦPSII 的减少。与晚期融化地块中的植物相比，早期融化地块中的植物暴露于更频繁和更严重的霜冻事件中，并且在冬季和春季期间 ΦPSII 显示出更明显的下降。通过相对电解质泄漏评估，融雪时间对电池损坏程度没有明显影响。我们的结果表明，亚北极高山 V. vitis-idaea 目前在小空间尺度上暴露于强烈的气候变化，类似于预计由气候变化引起的气候变化，而没有造成重大损害。我们得出结论，V。vitis-idaea 可有效减轻因融雪时间不同而导致的霜冻暴露差异较大的影响。这表明 V. vitis-idaea 将能够适应持续的气候变化。