The extent of snow cover over the northern hemisphere reached about 50% (in February 1972). At maximum, 55% of the terrestrial area of the northern hemisphere is seasonally frozen ground. Recently, plant-soil systems in these ecosystems have been more frequently subject to decreased snow cover and warmer temperatures during winter. Consequently, the change in winter conditions is likely to influence the organisms that constitute plant-soil systems (e.g. plants, soil fauna, and soil microbes) and the associated biogeochemical cycles. Furthermore, winter climate change can affect the species interactions that maintain the biodiversity in terrestrial ecosystems. However, winter has received much less attention by researchers than the so-called growing season.

In this symposium, we summarize the current knowledge in winter ecology and also the results of recent manipulative experiments on winter climate. Finally, we would like to discuss the importance of taking the effects of winter on plant-soils systems into consideration to predict the future of terrestrial ecosystems.