Fagus sylvatica forms the treeline across the Apennines mountain range, with an average elevation of 1589 m a.s.l. Previous studies evidenced that the current position of the treeline in the Apennines is heavily depressed as a result of a complex interaction between climatic factors and the past human pressure. In this study we correlated treeline elevation in the fifteen major mountain groups in the Apennines with selected climatic, geomorphological, and human disturbance variables in order to investigate in detail the site-specific features affecting the current treeline distribution. Treeline elevation was lowest in the North Italy (Apuan Alps), while the highest treeline was found in Central Italy (Simbruini). An absolute maximum treeline elevation of F. sylvatica exceeding 2000 m a.s.l. was found on 13 mountain peaks in Central and Southern Italy. Noteworthy, treeline elevation was largely lower on warmer south-facing slopes compared to northern slopes, with values several hundred meters lower in the Gran Sasso and Velino-Sirente. Although the causes of this pattern are still unknown, we argue that treeline elevation on south-facing slopes may be limited by the combination of climatic constraints (i.e. summer drought) and human disturbance. Evidence of a pervasive anthropogenic effect depressing treeline elevation was found in the North (Apuan Alps) Central (Gran Sasso, Velino-Sirente, Sibillini) and Southern part of Apennines (Pollino). By contrast, treeline elevation of the Laga, Simbruini, and Orsomarso mountain groups appears less affected by past anthropogenic disturbance. Finally, we recorded in the several mountain groups (i.e. Majella, Marsicani and Pollino) the coexistence of very depressed treelines just a few kilometers away from much higher treelines, among the highest ever recorded for F. sylvatica. Finally, we argue that F. sylvatica treeline across the Apennines is locally shaped both by the interaction of low temperatures experienced by the species in its earliest life stages in snow-free open spaces with summer soil water depletion and human disturbance.

中文翻译：

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气候和人为因素解释了亚平宁山脉15个山地群中的Fagus sylvatica林线海拔变化

Fagus sylvatica形成整个亚平宁山脉的树线，平均海拔1589 m asl先前的研究表明，由于气候因素和过去的人类压力之间复杂的相互作用，亚平宁山脉的树线当前位置受到严重压抑。在这项研究中，我们将亚平宁山脉15个主要山区的树线标高与选定的气候，地貌和人为干扰变量相关联，以详细研究影响当前树线分布的特定地点特征。树线海拔在意大利北部（阿普安阿尔卑斯山）最低，而在意大利中部（辛布鲁尼）则最高。林分绝对绝对最大海拔超过2000 m asl 在意大利中部和南部的13个山峰上发现。值得注意的是，与北坡相比，南坡暖坡的树线高度大大降低，在格兰萨索和韦利诺-西伦特低一些。尽管这种模式的原因仍然未知，但我们认为，朝南的斜坡上树线的升高可能受到气候条件（例如夏季干旱）和人为干扰的共同限制。在北部（阿普安阿尔卑斯山）中部（格兰萨索，维利诺-西伦特，西比里尼）和亚平宁山脉的南部（波利诺）发现了普遍的人为影响降低林线高度的证据。相比之下，Laga，Simbruini和Orsomarso山脉的树线高程似乎受过去人为干扰的影响较小。最后，我们在几个山脉中（即马耶拉，马尔西卡尼和波利诺）记录了非常郁闷的林线并存，距高得多的林线只有几公里，是有史以来最高的林木。最后，我们认为整个亚平宁山脉的西番莲木线是局部形成的，这是由于该物种在其生命的早期阶段在无雪开放空间中经历的低温与夏季土壤水分枯竭和人为干扰之间的相互作用。