Abstract In alpine ecosystems, imbibed seeds are often exposed to temperatures as low as −35 °C, challenging their survival in the soil. Here, we show that seeds have mechanisms to survive cold climate prevalent in alpine ecosystems and have identified three such mechanisms from existing literature, including two forms of freezing avoidance (the presence of water impermeable seed coats, and the supercooling of seed tissues) and one form of freezing tolerance (by extracellular-freezing). Experimentally-derived published data on the lowest temperature recorded at which 50% of a seed sample survived (i.e., lethal temperature; LT50) was used to generate a dataset of 24 species across low altitude, boreal and alpine environments. We assumed that the ability of seeds to maintain viability at very low temperatures would increase in species associated with higher altitudes conferring a competitive advantage that would be lost under projected climate change. However, our results reveal to underpin that seeds from boreal species survive relatively better at lower temperatures than those of alpine species. Paradoxically, a warming climate could lead to alpine seed death due to extremes of cold at the soil surface resulting from snow cover loss, whilst the declining snow cover may facilitate boreal forest colonization above the current treeline.

中文翻译：

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低温种子存活：气候变化下影响高海拔社区水平变化的潜在选择因素

摘要 在高山生态系统中，吸收的种子经常暴露在低至 -35 °C 的温度下，这对它们在土壤中的生存提出了挑战。在这里，我们展示了种子具有在高山生态系统中普遍存在的寒冷气候中生存的机制，并从现有文献中确定了三种这样的机制，包括两种形式的防冻（不透水种皮的存在和种子组织的过冷）和一种冷冻耐受的形式（通过细胞外冷冻）。实验得出的已发表的关于种子样本 50% 存活的最低温度（即致死温度；LT50）的已发表数据用于生成低海拔、北方和高山环境中 24 个物种的数据集。我们假设种子在极低温度下保持活力的能力会增加与较高海拔相关的物种，从而赋予竞争优势，而在预计的气候变化下会失去这种优势。然而，我们的结果表明，与高山物种相比，来自北方物种的种子在较低温度下相对更好地存活。矛盾的是，气候变暖可能会导致高山种子死亡，原因是积雪减少导致土壤表面极度寒冷，而积雪减少可能促进当前林木线以上的北方森林殖民。我们的结果表明，与高山物种相比，来自北方物种的种子在较低温度下相对更好地存活。矛盾的是，气候变暖可能会导致高山种子死亡，原因是积雪损失导致土壤表面极度寒冷，而积雪减少可能会促进当前林木线以上的北方森林殖民。我们的结果表明，与高山物种相比，来自北方物种的种子在较低温度下相对更好地存活。矛盾的是，气候变暖可能会导致高山种子死亡，原因是积雪减少导致土壤表面极度寒冷，而积雪减少可能促进当前林木线以上的北方森林殖民。