Altwegg Res, Roulin Alexandre, Kestenholz Matthias, Jenni Lukas
Department of Biology, University of Victoria, Victoria, BC, Canada.
Oecologia. 2006 Aug;149(1):44-51. doi: 10.1007/s00442-006-0430-3. Epub 2006 Apr 28.
Extreme weather events can lead to immediate catastrophic mortality. Due to their rare occurrence, however, the long-term impacts of such events for ecological processes are unclear. We examined the effect of extreme winters on barn owl (Tyto alba) survival and reproduction in Switzerland over a 68-year period (approximately 20 generations). This long-term data set allowed us to compare events that occurred only once in several decades to more frequent events. Winter harshness explained 17 and 49% of the variance in juvenile and adult survival, respectively, and the two harshest winters were associated with major population crashes caused by simultaneous low juvenile and adult survival. These two winters increased the correlation between juvenile and adult survival from 0.63 to 0.69. Overall, survival decreased non-linearly with increasing winter harshness in adults, and linearly in juveniles. In contrast, brood size was not related to the harshness of the preceding winter. Our results thus reveal complex interactions between climate and demography. The relationship between weather and survival observed during regular years is likely to underestimate the importance of climate variation for population dynamics.
极端天气事件可导致直接的灾难性死亡。然而，由于此类事件罕见，其对生态过程的长期影响尚不清楚。我们研究了在68年期间（约20代）极端冬季对瑞士仓鸮（Tyto alba）生存和繁殖的影响。这个长期数据集使我们能够将几十年才发生一次的事件与更频繁发生的事件进行比较。冬季严酷程度分别解释了幼鸟和成鸟生存变异的17%和49%，两个最严酷的冬季与幼鸟和成鸟同时低生存率导致的主要种群崩溃有关。这两个冬季使幼鸟和成鸟生存之间的相关性从0.63增加到0.69。总体而言，成鸟的生存率随着冬季严酷程度的增加呈非线性下降，而幼鸟则呈线性下降。相比之下，窝卵数与前一个冬季的严酷程度无关。因此，我们的结果揭示了气候与种群统计学之间的复杂相互作用。正常年份观察到的天气与生存之间的关系可能低估了气候变化对种群动态的重要性。
