Hannah Sørine Gerlich , Martin Holmstrup, Niels Martin Schmidt, Toke T. Høye

Arthropods respond to climate change by shifting their phenology in the spring and summer seasons. These phenological shifts are rarely uniform, and taxa show distinct variation in the direction and magnitude of phenological responses to climate drivers. To gain insights into the most climate-sensitive taxa and forecast the implications of climate change on community-wide activity and biotic interactions, it is important to understand how the climate affects the timing of activity of different taxa in local sites within a community. Here, we examined the temporal trends of arthropod phenology, and associations between arthropod phenological responses and climate predictors using arthropod monitoring data from five different habitats in high-Arctic Greenland covering a 25-year period. We found that, for most taxa, advanced arthropod phenology was associated with earlier snowmelt, and, to a lesser extent, warmer temperatures. However, the magnitude of advanced activity varied considerably between arthropod taxa and local habitats. Our study also revealed that pollinators were the most climate-sensitive group, with advanced and, in some habitats, shortened seasonal activities. Late active taxa and late snow melting habitats advanced phenology at greater magnitudes than early active taxa and early snow melting habitats. The magnitude of phenological shifts of arthropod taxa was dependent on habitat, highlighting the substantial spatial variation in phenological responses. Overall, our results demonstrate that high-Arctic arthropods are capable of tracking local climate drivers of phenology well, but the phenological responses of arthropod taxa to global climate change are complex, and community-wide trends may mask the variation in direction and magnitude of phenological shifts in different taxa and locally adapted populations.