The winter season is warming faster than any other season in temperate and polar regions, resulting in an overall loss of snow. In temperate grasslands (prairies), the loss of snow can substantially change the temperatures which organisms experience during winter as soils are exposed to more extreme cold conditions. Fire is another important factor affecting community composition in prairies. The timing of fire relative to winter could have an important interactive effect with lower snow cover. Specifically, burning accumulated litter prior to winter leaves plant seeds, buds, and roots even more exposed to extreme cold temperatures. Here we pair long-term (60 year) observations of prairie and savanna plant community change across a gradient of winter climate change with a field experiment manipulating snow depth and fire timing to better understand the consequences of winter climate change on prairie plant communities.
Results/Conclusions
Over the past 60 years, warming winter temperatures were related to increased extinction probabilities for spring-blooming species, but not summer-blooming species. Also, fire had substantial positive effects in preventing plant extinction. Following the first two years of experimental treatments, reductions in snow depth cause colder and more variable soil temperatures but did not significantly affect plant growth. Also, burning prior to winter results in colder soil temperatures when snow depth is reduced. However, fire promoted plant growth for most species. Overall, these results suggest that winter climate has important effects on prairie plant health and that even though snow manipulations affected temperature dynamics in the soil, prairie plants are relatively resilient to these changes for now. Prescribed fire has very important effects on prairie plant dynamics and might counteract the potentially negative effects of future snow loss.