Abstract Montane cloud forests are incredibly biodiverse regions that exist globally at narrow elevation bands and are frequently under the presence of low-level clouds and fog. Increasing temperatures and rising cloud base heights threaten these ecosystems, and may reduce the duration of time that plants are exposed to fog. Some cloud forest species have adapted to cloud immersion and enhanced photosynthesis rates have been observed under such conditions. This manuscript tests a simple model for simulating stomatal conductance for vegetation under cloud immersion based on Jarvis's empirical formulation. The light-available energy function within the model is modified to reflect variability observed in Abies fraseri under sun, low cloud, and cloud immersed sky conditions in the Southern Appalachian Mountains. Results demonstrate that this approach captures differences amongst stomatal opening during sun, low cloud and immersed conditions for similar ranges of temperature, light, diffusivity, and xylem water potential. Simulated average stomatal conductance during cloud immersion exceeded estimates during sun and low cloud conditions by 3 and 1.5 times, respectively. The magnitude of the estimated stomatal conductance for immersed and low cloud conditions falls below experimental data under all potential environmental states. Similarly, transpiration rates estimated from modeled stomatal conductance were also lower than observed values. The larger discrepancy for cloud immersed periods highlights the need to account for plant adaptation strategies like reduced transpiration and foliar uptake that occur during cloud immersion. Simulating adaptation processes for cloud forests in modeling studies is critical in order to evaluate fully the resilience of montane cloud forest vegetation under disturbance regimes.

中文翻译：

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模拟南阿巴拉契亚山脉山地云林对云浸入的气孔响应

摘要 山地云雾林是全球范围内生物多样性极其丰富的地区，分布在狭窄的高程带上，经常存在低层云雾。气温升高和云底高度上升威胁到这些生态系统，并可能缩短植物暴露在雾中的时间。一些云林物种已经适应了云浸，并且在这种条件下观察到了光合作用速率的提高。这份手稿基于 Jarvis 的经验公式测试了一个简单的模型，用于模拟云浸没下植被的气孔导度。模型中的光可用能量函数经过修改，以反映在南阿巴拉契亚山脉的太阳、低云和云浸入天空条件下在冷杉中观察到的变化。结果表明，这种方法捕捉到了在阳光、低云和浸没条件下气孔开口在温度、光、扩散率和木质部水势相似范围内的差异。云浸入期间模拟的平均气孔导度分别超过太阳和低云条件下的估计值 3 倍和 1.5 倍。在所有潜在环境状态下，浸没和低云条件下估计的气孔导度的幅度低于实验数据。同样，根据模拟气孔导度估计的蒸腾速率也低于观察值。云浸时间的较大差异突出表明需要考虑植物适应策略，例如在云浸期间发生的蒸腾作用和叶面吸收减少。