Historical data reveal earlier flowering under environmental change

Global temperatures have risen ~ 1.1°C since the 1800s and the mean annual air temperature in the Arctic has increased by nearly four times the global average. Temperature has a significant effect on fundamental life‐cycle events of flora and fauna. With temperatures increasing, Arctic plants are expected to shift their active periods accordingly, with a shorter flowering period as later flowering plants converge with flowering timing of early flowering plants. Nearly 120 years of herbarium records and collection data were leveraged to identify flowering shifts in the Arctic–alpine plant Oxyria digyna using climatic data and linear regressions. We found that alpine, boreal Arctic, and Arctic tundra populations of Oxyria digyna differed in their flowering time response to increased air temperature. The boreal Arctic population showed a significant advancement in flowering time as related to mean summer and June temperature increases, while the flowering time of Arctic tundra and alpine populations had a shift in flowering timing in response to June temperature change. Our results identify biodiversity response to climate change and determine which populations have greater adaptive potential to respond to rapidly changing abiotic conditions in the Arctic and beyond.