On October 18th, during an interview with researcher Su Yanjun from the Chinese Academy of Sciences’ Institute of Botany, we discussed a recent study that sheds light on the autumn phenology of temperate forests and its connection to climate change.
Su’s team selected six typical northern temperate forest sites and utilized advanced technologies such as lidar and high-resolution imagery to precisely quantify the relationship between autumn phenology and forest canopy structure. Their findings revealed a significant and consistent relationship between the two, indicating that the forest canopy structure influences autumn phenology primarily by regulating microclimatic factors such as radiation and temperature within the forest.
“The existing research generally views macroclimate as the main driver of temporal and spatial variations in autumn phenology,” Su explained. “However, macroclimate alone cannot account for the local spatial variability in autumn phenology. Even within regions experiencing the same macroclimate conditions, we observe considerable spatial differences in the autumn phenology of identical tree species.”
Unlike macroclimate, which describes broader climatic patterns, microclimate reflects localized climate conditions directly affecting tree growth. Su noted that complex canopy structures can weaken light penetration, thereby reducing photosynthesis intensity and delaying the time it takes for plants to reach ‘carbon saturation,’ which, in turn, postpones the onset of autumn phenology. Additionally, such structures can enhance temperature buffering, slow down the accumulation of chilling hours, and reduce the risk of frost damage, further delaying autumn phenology.
Further analysis by the team indicated that integrating the “canopy structure-microclimate-autumn phenology” regulatory mechanism into traditional autumn phenology models significantly improves prediction accuracy. In contrast, traditional models that overlook this mechanism tend to overestimate the delaying effects of global warming on autumn phenology.
This crucial research, conducted in collaboration with partners from Peking University, the University of Hong Kong, and KU Leuven in Belgium, has been published in the international academic journal “Nature Climate Change.” Su emphasized that understanding the local spatial variability of autumn phenology in temperate forests is essential for predicting how it might respond to climate change and for assessing the forests’ carbon sequestration capabilities.
