Asymmetric winter warming advanced plant phenology to a greater extent than symmetric warming in an alpine meadow

The warming of terrestrial high-latitude ecosystems, while increasing, will likely be asymmetric across seasons – where winter non-growing seasons will warm more than summer growing seasons. Asymmetric winter warming in temperature-sensitive ecosystems may delay spring phenological events by reducing the opportunity that a plants’ chilling requirement is met. Similarly, symmetric warming can advance spring phenology.
To explore the impact of asymmetric warming on plant phenology, we applied a year-round warming and a winter warming treatment to our experimental plots. Over a two-year period, we monitored leaf-out and flowering phenology for 11 plant species.
There was variation among species, however, both winter and year-round warming, advanced the leaf-out day and the first flowering day relative to the control treatment. Winter warming advanced leaf-out and flowering phenology by 11.1 (± 2.4) and 12.6 (± 2.9) days, respectively. However, year-round warming had less of an impact adv...