Johnsen Kaja, Boonstra Rudy, Boutin Stan, Devineau Olivier, Krebs Charles J, Andreassen Harry P
Faculty of Applied Ecology and Agricultural Science Hedmark University of Applied Sciences Koppang Norway.
Department of Biological Sciences University of Toronto Scarborough Toronto ON Canada.
Ecol Evol. 2016 Dec 14;7(1):115-124. doi: 10.1002/ece3.2635. eCollection 2017 Jan.
Vole population cycles are a major force driving boreal ecosystem dynamics in northwestern Eurasia. However, our understanding of the impact of winter on these cycles is increasingly uncertain, especially because climate change is affecting snow predictability, quality, and abundance. We examined the role of winter weather and snow conditions, the lack of suitable habitat structure during freeze-thaw periods, and the lack of sufficient food as potential causes for winter population crashes. We live-trapped bank voles on 26 plots (0.36 ha each) at two different elevations (representing different winter conditions) in southeast Norway in the winters 2013/2014 and 2014/2015. We carried out two manipulations: supplementing six plots with food to eliminate food limitation and six plots with straw to improve habitat structure and limit the effect of icing in the subnivean space. In the first winter, all bank voles survived well on all plots, whereas in the second winter voles on almost all plots went extinct except for those receiving supplemental food. Survival was highest on the feeding treatment in both winters, whereas improving habitat structure had no effect. We conclude that food limitation was a key factor in causing winter population crashes.
田鼠种群数量的周期性变化是推动欧亚大陆西北部寒带生态系统动态变化的主要力量。然而，我们对冬季对这些周期性变化的影响的理解越来越不确定，尤其是因为气候变化正在影响降雪的可预测性、质量和丰度。我们研究了冬季天气和雪况、冻融期缺乏合适的栖息地结构以及缺乏足够食物作为冬季种群数量锐减的潜在原因。在2013/2014年和2014/2015年冬季，我们在挪威东南部两个不同海拔（代表不同冬季条件）的26个样地（每个样地0.36公顷）上对河岸田鼠进行了活体捕捉。我们进行了两项操作：给六个样地补充食物以消除食物限制，给六个样地添加稻草以改善栖息地结构并限制雪下空间结冰的影响。在第一个冬季，所有样地上的河岸田鼠都存活良好，而在第二个冬季，除了接受补充食物的田鼠外，几乎所有样地上的田鼠都灭绝了。在两个冬季中，喂食处理下的田鼠存活率最高，而改善栖息地结构则没有效果。我们得出结论，食物限制是导致冬季种群数量锐减的关键因素。
