Woody vegetation at the upper limit of its growth is a sensitive indicator of climate change. The aim of this study is to provide an analysis of the centuries-old spatiotemporal dynamics of larch trees at the upper limit of their growth (mountain massif Rai-Iz, Polar Urals, Russia). We used a ground-based method of mapping the remnants of trees that grew in the study area and died during the Little Ice Age. Aerial photographs from the 1960s and high-spatial-resolution satellite images from 2015 were used as data sources to define the locations of trees. Maps of the forest–tundra phytocoenochoras (areas of the terrain that are relatively homogeneous for one or more components of vegetation and/or other indicators) were created using a modified method of boundary detection between forest parcels with different stand densities. The proposed method of boundary detection between the main types of phytocoenochoras allowed us to identify a 15% total increase in areas of closed and open forest and areas with sparse tree growth, as well as a decrease in areas of tundra with single trees over these last decades. Using our spatiotemporal analysis of forest–tundra demographics over the last 50 years, we found that the number of trees in the ecotone had doubled. However, modern trees have not yet reached the areas occupied by trees in the past.

中文翻译：

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极地乌拉尔上林线过渡带的树木：百年历史的变化和空间格局

木本植物植被生长的上限是气候变化的敏感指标。这项研究的目的是提供对落叶松树木生长上限的百年历史时空动态的分析（山地块Rai-Iz，极地乌拉尔，俄罗斯）。我们使用了一种基于地面的方法来绘制在研究区域生长并在小冰期死亡的树木残余物的地图。1960年代的航拍照片和2015年的高空间分辨率卫星图像被用作定义树木位置的数据源。使用改良的边界密度不同的林地间边界检测方法，创建了森林–苔原植物群落（地形对于一种或多种植被成分和/或其他指标而言相对均一的区域）的地图。提议的主要植物尾藻种类之间的边界检测方法使我们能够识别出封闭森林和开阔森林面积以及树木稀疏地区的总增加量为15％，以及在过去的最后几年中单棵树木的冻原面积的减少量几十年。通过对过去50年中森林苔原的人口统计数据进行时空分析，我们发现过渡带的树木数量增加了一倍。然而，过去现代树木尚未到达树木所占据的区域。通过对过去50年中森林苔原的人口统计数据进行时空分析，我们发现过渡带的树木数量增加了一倍。然而，过去现代树木尚未到达树木所占据的区域。使用我们过去50年对森林苔原的人口统计数据的时空分析，我们发现过渡带的树木数量增加了一倍。然而，过去现代树木尚未到达树木所占据的区域。