New progress has been made in the study of tree radial growth in response to phenological changes

Under the guidance of Huang Jianguo, researcher of the South China Botanical Garden of the Chinese Academy of Sciences, Ding Xiaogang, professor of the Guangdong Academy of Forestry, and Ma Qianqian, associate researcher of the South China Botanical Garden of the Chinese Academy of Sciences, the study found that the initial stage of tree growth affects radial growth by adjusting the cumulative growth rate in advance. The relevant results were recently published in Agroforestry Meteorology.

Map of the path of North (A) and South (B). The numbers in the plot represent the mean and standard error of the normalized path coefficients. Photo courtesy of the research team

Climate change is profoundly affecting forest phenology, especially in the northern hemisphere. However, how radial tree growth responds to phenological changes remains to be explored. The boreal forests in the Northern Hemisphere are among the largest biomes on Earth, and their tree growth dynamics are significant for global change. Therefore, it is necessary to analyze the specific response process of tree growth to phenology, so as to provide a theoretical basis for accurate assessment of carbon sink potential and forest dynamic prediction on a larger scale.

By constructing a tree-ring chronology network in Central Asia, the researchers divided the study area into north and south parts bounded by 49° north latitude. The simulation results based on the VS model show that the start time (SoGS) of the tree growing season (SoGS) from 1959 to 2010/2016 is significantly earlier. Among them, SoGS in the northern part of the study area was significantly negatively correlated with radial growth, while the southern part of the study area was not significantly correlated. The results of the pathway analysis show that the response of radial growth between north and south to earlier SoGS is not consistent.

In the North, radial growth was mainly driven by the easing of low temperature limits, thereby increasing the cumulative growth rate. In the relatively arid south, drought stress early in the growing season counteracts the positive effects of temperature on tree radial growth by reducing the cumulative growth rate. Overall, advance SoGS affects the radial growth of trees by regulating the cumulative growth rate.

This study revealed the spatial differences affecting the radial growth of trees in advance of growth initiation under the background of climate change, and clarified the mechanism of phenological changes affecting radial growth by regulating the cumulative growth rate. The results of the study can help to more accurately estimate the dynamics of boreal forests under climate change, and provide a basis for regional forest management and ecological restoration of boreal forests.

The above research was supported by the National Natural Science Foundation of China and the Natural Science Foundation of Guangdong Province. (Source: China Science News Zhu Hanbin)

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