Long-term linear trends mask phenological shifts

Climate warming has substantially advanced the timing of leaf unfolding, while the temperature sensitivity of leaf unfolding (ST) was significantly reduced over the past three decades according to our recent study (Fu et al. 2015). We are very happy to see that the article from Wang et al. (2016) confirmed these findings using a 15year window, despite using only 927 species-site combinations, which are about one sixth of the species sites (5472) used in our study. However, we cannot agree with the highlighted conclusion that the significant decrease in ST using the 15-year window is not sustained when examining longer-term phenological responses to climate warming. On the contrary, we argue that the long-term linear trends may mask short-term phenological shifts. According to the IPCCAR5, the period since the 1980s was very likely the warmest 30-year period of the last 800 years in the Northern Hemisphere (IPCC, Climate Change 2013); we therefore investigated the phenological changes during this warmest period (Fu et al. 2015). We welcome Wang et al’s study that extended our analyses back to the 1950s and found that ST slightly increased before the 1980s. However, they provided no explanation for this increase and did not quantify the intensity of chilling during this extended period. In addition, it should be noted that previous analyses of phenological data since 1753 in Switzerland also suggested long-term changes in ST based on 30-year windows (Rutishauser et al. 2008). This result actually supports our conclusion that changes in the number of chilling days can elicit changes in ST. As shown