Aim: Large and ecologically functioning steppe complexes have been lost historically across the globe, but recent land-use changes may allow the reversal of this trend in some regions. We aimed to develop and map indicators of changing human influence using satellite imagery and historical maps, and to use these indicators to identify areas for broad-scale steppe rewilding. Location: Eurasian steppes of Kazakhstan. Methods: We mapped decreasing human influence indicated by cropland abandonment, declining grazing pressure and rural outmigration in the steppes of northern Kazakhstan. We did this by processing 5,500 Landsat scenes to map changes in cropland between 1990 and 2015, and by digitizing Soviet topographic maps and examining recent high-resolution satellite imagery to assess the degree of abandonment of >2,000 settlements and >1,300 livestock stations. We combined this information into a human influence index (HI), mapped changes in HI to highlight where rewilding might take place and assessed how this affected the connectivity of steppe habitat. Results: Across our study area, about 6.2 million ha of cropland were abandoned (30.5\%), 14\% of all settlements were fully and 81\% partly abandoned, and 76\% of livestock stations were completely dismantled between 1990 and 2015, suggesting substantially decreasing human pressure across vast areas. This resulted in increased connectivity of steppe habitat. Main conclusions: The steppes of Eurasia are experiencing massively declining human influence, suggesting large-scale passive rewilding is taking place. Many of these areas are now important for the connectivity of the wider steppe landscape and can provide habitat for endangered megafauna such as the critically endangered saiga antelope. Yet, this window of opportunity may soon close, as recultivation of abandoned cropland is gaining momentum. Our aggregate human influence index captures key components of rewilding and can help to devise strategies for fostering large, connected networks of protected areas in the steppe.

中文翻译：

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欧亚大陆草原上人类压力的下降和重新野化的机会

目标：历史上，全球范围内的大型生态功能草原复合体已经消失，但最近的土地利用变化可能会在某些地区逆转这一趋势。我们的目标是使用卫星图像和历史地图开发和绘制人类影响变化的指标，并使用这些指标来确定大范围草原野化的区域。地点：哈萨克斯坦的欧亚大草原。方法：我们绘制了哈萨克斯坦北部大草原因农田废弃、放牧压力下降和农村人口迁徙而减少的人类影响图。为此，我们处理了 5,500 个 Landsat 场景以绘制 1990 年至 2015 年间农田变化的地图，并通过数字化苏联地形图和检查最近的高分辨率卫星图像来评估 >2,000 和 >1 的废弃程度，300个畜牧站。我们将这些信息结合到人类影响指数 (HI) 中，绘制 HI 的变化以突出可能发生野化的位置，并评估这如何影响草原栖息地的连通性。结果：在我们的研究区域，1990 年至 2015 年间，大约 620 万公顷农田被废弃（30.5%），14% 的所有聚居地完全废弃，81% 部分废弃，76% 的畜牧站被完全拆除，表明在广大地区大大减少了人类压力。这导致草原栖息地的连通性增加。主要结论：欧亚大陆的草原正在经历人类影响力的大幅下降，表明正在发生大规模的被动野化。其中许多地区现在对于更广泛的草原景观的连通性很重要，并且可以为濒临灭绝的巨型动物提供栖息地，例如极度濒危的赛加羚羊。然而，这个机会之窗可能很快就会关闭，因为废弃农田的重新耕种势头正在增强。我们的综合人类影响指数捕捉了野化的关键组成部分，可以帮助制定战略，以在草原上培育大型、相互连接的保护区网络。