Plant phenology has been intensively studied because it is closed related with interannual variability of carbon captured by terrestrial ecosystems.

Prof. WU Chaoyang’s team at The Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (IGSNRR, CAS) found that autumn-leaf senescence responded oppositely to the increase of daytime and nighttime temperatures, and leaf senescence in the Norther Hemisphere would begin earlier than currently expected, causing a positive feedback on climate change. This work was published in Nature Climate Change.

In contrast to the well-known response of spring phenology to climate change, autumn phenology is more challenging to prdict.

Using long-term ground phenological records (14536 time series since the 1900s) and satellite greenness observations dating back to the 1980s, researchers reported an unrecognized opposite change of leaf senescence with daytime and nighttime warming. If higher daytime temperature leads to an earlier or later leaf senescence, an increase in nighttime temperature systematically drives leaf senescence to occur oppositely.

Contrasting impacts of daytime and nighttime warming on drought stress may be the underlying mechanism for this opposing relationship.

This study changes the paradigm of prolonged growth by a higher autumn temperature, and predicts an earlier leaf senescence in the Norther Hemisphere, causing a positive feedback on climate change.

The study was funded by the Strategic Priority Research Program of the Chinese Academy of Sciences, National Natural Science Foundation of China, and also in collaboration with many climate change scientists around the world, including Philippe Ciais from France, Josep Pe？uelas from Spain, Ranga B. Myneni from USA and Jing M. Chen from Canada.

Contrasting responses of autumn-leaf senescence to daytime and nighttime warming using ground and satellite observations (Image by WU Chaoyang)