Across China: Scientists unveil how temperate forest canopy structure influences autumn phenology

BEIJING, Oct. 19 (Xinhua) — Scientists uncover the mechanism by which temperate forest canopy structure influences autumn phenology, providing a scientific basis for predicting both autumn phenology’s response to climate change and the forest’s carbon sequestration capacity.
Autumn phenology refers to the periodic changes exhibited by organisms such as plants and animals during the autumn season, influenced by environmental factors like temperature, light, and precipitation.
The study of autumn phenology is important for understanding the impacts of climate change, assessing the health of ecosystems, and predicting species’ adaptability.
Existing research generally suggests that macroclimate is the primary driver of temporal and spatial variation in autumn phenology.
However, within local areas experiencing similar macroclimatic conditions, the autumn phenology of the same tree species can still exhibit significant spatial differences. Currently, the mechanisms behind the local spatial variation in autumn phenology within temperate forests remain unclear.
Researchers from the Institute of Botany under the Chinese Academy of Sciences selected six typical northern temperate forest sites, using laser radar and high spatiotemporal resolution imagery data to accurately quantify information on autumn phenology and forest canopy structure, and found a significant and consistent relationship between the two.
The canopy structure primarily affects autumn phenology by regulating microclimate factors such as radiation and temperature within the forest, according to Su Yanjun, a researcher at the institute.
“A complex canopy structure can, on one hand, weaken light penetration within the forest, reducing the intensity of photosynthesis and delaying the time at which plants reach carbon saturation,” Su said.
“On the other hand, it can enhance the buffering effect of temperature, slow down the rate of cold accumulated temperature and reduce the risk of plants from getting frost damage. All of these factors may delay the onset of autumn phenology,” he added.
The study also found that integrating the “canopy structure-microclimate-autumn phenology” regulatory mechanism into traditional autumn phenology models significantly improves the predictive accuracy of autumn phenology.
Traditional phenology models that do not consider this mechanism tend to overestimate the delaying effect of global warming on autumn phenology.
The study was published in the journal Nature Climate Change. ■