Harsh winters are a characteristic element of Arctic ecosystems, yet the importance of winter conditions for Arctic plant communities is still underrepresented in climate change impact studies. Here, we use fine-scale microclimate data with plot-scale records of vascular plants, lichens and bryophytes from three Arctic areas, and show that topographically heterogeneous tundra holds marked spatial variation, especially in winter temperatures. Winter conditions are the strongest environmental variable related to the fine-scale patterns in tundra vegetation, whereas summer temperatures mainly explain the coarse-scale differences among the Arctic areas. Nonetheless, the three plant groups (and also individual species) show often contrasting and complex responses along the local environmental gradients. Our results highlight the importance of local conditions and heterogeneity for tundra plants, and knowing that the Arctic winters are warming faster than summers, a greater focus should be placed on winter conditions in simulations of climate change impacts in tundra ecosystems.

严酷的冬季是北极生态系统的一个特征性要素，但是在气候变化影响研究中，冬季条件对北极植物群落的重要性仍然不足。在这里，我们使用精细的微气候数据以及来自三个北极地区的维管植物，地衣和苔藓植物的地块规模记录，并显示地形异质的苔原具有明显的空间变化，尤其是在冬季温度下。冬季条件是与苔原植被的精细尺度模式有关的最强环境变量，而夏季温度主要解释了北极地区之间的粗糙尺度差异。尽管如此，这三个植物群（以及单个物种）在局部环境梯度上通常表现出不同而复杂的响应。