Abstract Forest microclimate is strongly affected by local topography and management activities, as these directly alter overstory structure. In the present work we analysed the dependence of observed patterns of spatio-temporal microclimatic variations on topographic, canopy- and management-related factors. A forestry experiment was conducted in managed fir-beech forests in the Dinaric Mountains (Slovenia), which are characterized by rugged karstic terrain with numerous sinkholes. In 2012, cutting treatments representing a range in the intensity of overstory removal were performed: uncut controls (CON), 50% cut of stand growing stock (intermediate management intensity – IMI) and 100% cut (high management intensity – HMI) creating 0.4 ha canopy gaps. Fine-scale variation in aspect and slope and its effects on microclimate was assessed by comparing central, south-facing and north-facing within-sinkhole positions. We measured microclimatic variables (air temperature – T, relative humidity – RH) 0.5 m above the ground over three consecutive post-treatment growing seasons. Microclimatic variables showed an increase (T and vapour pressure deficit – VPD) or decrease (RH) with management intensity. Daily Tmax and VPDmax in HMI treatment were up to 5.9°C (on average 3.5°C) and up to 1.4 kPa (on average 0.6 kPa) higher than those in CON treatment, respectively, whereas daily RHmin was up to 22.7 (on average 13.0) percentage points lower. Regarding intra-seasonal patterns, microclimatic differences between treatments were largest during the summer. South-facing plots in the HMI treatment overall exhibited the most extreme conditions, i.e. the highest Tmax and lowest RHmin. Differences in microclimate between treatments were strongly modulated by canopy cover. The results also suggest that overstory removal increases topography-mediated variation in microclimate, as evidenced by significant differences in T, RH and VPD along the fine-scale topographic gradient within the created canopy gaps.

中文翻译：

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各种扦插处理及地形因素对第纳尔冷杉林小气候条件的影响

摘要 森林小气候受当地地形和管理活动的强烈影响，因为这些直接改变了上层结构。在目前的工作中，我们分析了观察到的时空小气候变化模式对地形、冠层和管理相关因素的依赖性。在 Dinaric 山脉（斯洛文尼亚）的管理冷杉山毛榉森林中进行了林业试验，该地区的特点是崎岖的岩溶地形和许多落水洞。2012 年，进行了代表覆盖层移除强度范围的切割处理：未切割控制 (CON)、50% 切割林分立木（中等管理强度 – IMI）和 100% 切割（高管理强度 – HMI）创建 0.4 ha 树冠缝隙。通过比较中央、朝南和朝北的天坑内位置，评估了坡向和坡度的精细尺度变化及其对小气候的影响。我们在连续三个处理后生长季节测量了离地面 0.5 m 的小气候变量（气温 - T，相对湿度 - RH）。小气候变量随着管理强度的增加（T 和蒸汽压差 – VPD）或减少（RH）而增加。HMI 治疗组的每日 Tmax 和 VPDmax 分别比 CON 治疗组高 5.9°C（平均 3.5°C）和 1.4 kPa（平均 0.6 kPa），而每日 RHmin 高达 22.7（平均13.0) 个百分点。关于季节性模式，夏季处理之间的小气候差异最大。HMI 处理中的朝南地块总体上表现出最极端的条件，即最高的 Tmax 和最低的 RHmin。处理之间的小气候差异受到冠层覆盖的强烈调节。结果还表明，覆盖层的移除增加了地形介导的小气候变化，这可以通过 T、RH 和 VPD 沿着形成的冠层间隙内的精细地形梯度的显着差异来证明。