Satellite observed delaying effects of increased winds on spring green-up dates

Wind speeds have substantially changed over the Northern Hemisphere during the past a few decades, and such changes have been shown to have important implications for the growth, chemical composition, structure, and morphology of terrestrial ecosystems. However, the effects of wind change on the spring leaf green-up date (GUD) remain largely unknown. Using both 89 sites of flux measurements (972 site-year in total) and satellite observations over 1982–2015, here we show that higher winds in the spring preseason contributed to the delayed GUD for 29.8% of northern ecosystems, and various factors controlled the strength of the delaying effects. We further show that the earlier GUD with climate change was offset roughly by 24.4 ± 3.7% due to the increase of wind. Higher winds potentially caused delayed GUD by changes in soil conditions and differences between daytime and night-time temperatures. A higher precipitation could likely compensate the drying effects of winds on GUD. Among different vegetation types, soil water and water use efficiency were the most important regulators of the sensitivity of GUD to wind for all plant functional types, while evapotranspiration regulated grasslands and shrubs. Our results identified the new role of wind change on the spring phenology in respective of satellite observations, and future ecosystem models might consider these effects for a better representation of the responses of vegetation phenology to climate change.