ABSTRACT

Spring green-up in arctic and alpine systems is predominantly controlled by temperature and snowmelt timing preceding and during the growing season. Variation in the timing of green-up across space is an important aspect of resource variability with which mobile herbivores must contend. Here, we measure the explanatory power of abiotic drivers of green-up in a Low Arctic region of west Greenland, host to a migratory caribou population. We identify inconsistent relationships between green-up and abiotic drivers across space. Whereas green-up timing is most closely related to snowmelt in some areas, in others it is most closely related to spring temperature. The negative correlation between the explanatory power of snowmelt and temperature suggests that at broad scales, where green-up is more constrained by snow cover, such as moist, mountainous coastal areas, it is less constrained by temperature. Where snow is less persistent through winter, such as cold, dry inland areas, temperature becomes the predominant factor driving green-up. If the principal driver of spring plant growth is inconsistent across a region, long-term trends in resource phenology could vary spatially. For seasonal migrants like caribou, synchronizing migration timing with resource phenology may be complicated by discordant interannual change across drivers of green-up timing.

摘要

北极和高山系统春季的绿化主要受生长季节之前和生长季节的温度和融雪时间控制。跨空间绿化时间的变化是资源变化的重要方面，移动食草动物必须应对这一变化。在这里，我们测量了迁徙的驯鹿种群所在的西格陵兰低北极地区非生物驱动绿化的解释力。我们发现绿色和非生物驱动程序之间的空间关系不一致。在某些地区，绿化时间与融雪最密切相关，而在其他地区，绿化时间与春季温度最密切相关。融雪的解释力与温度之间的负相关关系表明，在较宽的范围内，绿化更受积雪的限制，例如潮湿，山区沿海地区，温度受到的限制较小。在整个冬季降雪较少的地方，例如寒冷，干燥的内陆地区，温度成为推动绿化的主要因素。如果整个地区春季植物生长的主要驱动力不一致，则资源物候的长期趋势可能会在空间上发生变化。对于像北美驯鹿这样的季节性移民，由于绿色时间安排的驱动因素之间不一致的年际变化，使移民时间与资源物候同步可能会变得复杂。