Arctic plant phenology and abundance. Understanding temperature-sensitivity and warming impacts

Abstract

The Arctic is warming four times faster than the global average, driving major changes in tundra ecosystems. One key response is shifts in plant phenology, the timing of life events like flowering. These shifts can cause trophic mismatches, affecting insects, birds, mammals, and human societies. Plants that adjust their phenology with warming are considered temperature sensitive. Understanding plant phenology is key to predicting how tundra vegetation may change in the future. With this in mind, our study aims to understand the relationship between temperature sensitivity of plant phenology and abundance change, both experimentally and over time with natural warming. We used an experimental setup in Greenland, Disko Island, with warming chambers (open top chambers, OTC), creating a 1.5–3°C warmer and more humid environment, and monitored plant phenology in both OTCs and control plots. Previously recorded abundance data from the same site was used to see how experimental warming affected abundance, along with a 30-years old dataset to explore changes over time with natural climate warming. Our results showed that flowering time advanced with warming, indicating that most species were temperature sensitive. Betula nana and Bistorta vivipara were most sensitive, flowering 7 and 15 days earlier, respectively, under experimental warming. We found no strong overall trend of increased abundance under experimental warming; over time the trend was more positive but still modest. B. nana consistently increased under both experimental and natural warming, while B. vivipara showed a continuous decline. Overall, we found that temperature sensitivity alone did not predict abundance changes. This suggests that other environmental factors (e.g. microclimate variation, soil conditions, and species interactions) likely play important roles. Our study also highlights species-specific responses, with shrubs like B. nana would likely expand, while species like B. vivipara may struggle in a warmer Arctic.