FLOWERING TIME DEPENDENCE ON MICROCLIMATE ACROSS AN ELEVATIONAL GRADIENT IN ARCTIC PLANT COMMUNITIES

Abstract: The Arctic is the fastest-warming region on Earth. Arctic plant communities are highly sensitive to temperature change; temperature-dependent advancement of flowering dates has already been observed in the Arctic. Flowering time is critical for reproductive success. Flowering at the wrong time can reduce seed set through a decreased chance of getting pollinated, or frost damage of the flowers. Knowledge of the factors that influence phenological events gives insight to the response potential of both the community and individual species. This work aimed to investigate the relationship between flowering time and elevation. I attempted to answer the following question: “How does the flowering time relate to elevation?” I hypothesized that flowering would occur earlier at lower elevations because of the higher temperature and earlier snowmelt. To test my hypothesis, I compared the flowering time at five different elevations, spanning an elevational gradient between 700-1500 meters above sea level. I identified dates of flowering peaks using a series of timelapse images taken by field-deployed cameras in the summer of 2020 in Latnjajaure, Lapland. Additionally, I analyzed temperature data for the same locations. There was a strong correlation between elevation and temperature. However, the flowering time of the communities was not dependent on the elevation. Three species were found in more than one plot. Surprisingly, the flowering time of these species occurred almost 30 days later at the lower elevation. This extreme delay in flowering could be due to unusually late snowmelt in the plot, as the timing of snowmelt can vary on a very small scale. In conclusion, we see a high variation of flowering times at both community level and species level, likely as a result of large variation in environmental conditions other than temperature on a very small scale.