As found by comparing historical topographic maps and present-day satellite images, steppificated areas in the southern part of the eastern macroslope of the Southern Urals have decreased in size by 17.6% between 1986 and 2015 due to forest expansion. Analysis of the age structure of tree stands in the forest–mountain steppe ecotone provided evidence for intense pine and larch regeneration in this region from 1915 to the 1960s, which has led to significant increase in stand density and upward shift of treelines along slopes and ravines by the end of the 20th century. Intense pine regeneration during the past 35–40 years has been observed at the boundary between closed and open forests and in sparse woodlands. Forest expansion to the mountain steppes throughout the ecotone proceeded against the background of increase in temperature and precipitation during the cold period of the year. The rate of forest expansion to particular areas varied depending on differences in moisture supply, which, in turn, depended on local microclimatic and edaphic conditions. This is confirmed by our measurements of snow depth and density and soil moisture and thickness, which show that forest has expanded at the highest rate in more snowy and moisture-abundant slope areas.

中文翻译：

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与气候和栖息地湿度变化相关的南乌拉尔森林-山地草原交错带中树木植被的扩张

通过比较历史地形图和现代卫星图像发现，1986 年至 2015 年间，由于森林扩张，南乌拉尔东部大斜坡南部的阶梯状区域面积减少了 17.6%。对林山草原交错带林分年龄结构的分析为该地区松树和落叶松在 1915 至 1960 年代的强烈更新提供了证据，这导致林分密度显着增加，沿斜坡和沟壑的林木线向上移动到 20 世纪末。在过去 35-40 年间，在封闭森林和开放森林之间的边界以及稀疏的林地中观察到了强烈的松树再生。整个交错带的森林向山地草原扩张是在一年中寒冷时期气温和降水增加的背景下进行的。森林向特定地区扩张的速度取决于水分供应的差异，而水分供应又取决于当地的小气候和土壤条件。我们对积雪深度和密度以及土壤水分和厚度的测量证实了这一点，这表明森林在积雪较多和水分充足的斜坡区域以最高的速度扩张。