Arctic warming can influence tundra ecosystem function with consequences for climate feedbacks, wildlife and human communities. Yet ecological change across the Arctic tundra biome remains poorly quantified due to field measurement limitations and reliance on coarse-resolution satellite data. Here, we assess decadal changes in Arctic tundra greenness using time series from the 30 m resolution Landsat satellites. From 1985 to 2016 tundra greenness increased (greening) at ~37.3% of sampling sites and decreased (browning) at ~4.7% of sampling sites. Greening occurred most often at warm sampling sites with increased summer air temperature, soil temperature, and soil moisture, while browning occurred most often at cold sampling sites that cooled and dried. Tundra greenness was positively correlated with graminoid, shrub, and ecosystem productivity measured at field sites. Our results support the hypothesis that summer warming stimulated plant productivity across much, but not all, of the Arctic tundra biome during recent decades.

北极变暖会影响苔原生态系统的功能，从而对气候反馈、野生动物和人类社区产生影响。然而，由于现场测量的限制和对粗分辨率卫星数据的依赖，整个北极苔原生物群落的生态变化仍然很难量化。在这里，我们使用 30 m 分辨率 Landsat 卫星的时间序列评估北极苔原绿度的十年变化。从 1985 年到 2016 年，约 37.3% 的采样点的苔原绿度增加（变绿），约 4.7% 的采样点的苔原绿度下降（褐变）。绿化最常发生在夏季气温、土壤温度和土壤湿度升高的温暖采样点，而褐变最常发生在冷却和干燥的冷采样点。苔原绿度与实地测量的禾本科植物、灌木和生态系统生产力呈正相关。我们的结果支持这样的假设：近几十年来，夏季变暖刺激了北极苔原生物群落大部分（但不是全部）的植物生产力。