Location :Researchers Unveil Non-summer Hydrothermal Condition Variations in North Subtropical China Over the Past 200 Years
The subtropical regions of China lie in the core area of the Asian monsoon, having a large population and abundant forest resources, showing great potential in carbon sequestration.
Increasing global warming not only poses a threat of drought to China's subtropical regions, but also has a significant impact on the dormancy time of subtropical trees. This highlights the dominant role of non-growing season hydro (precipitation) - thermal (temperature) conditions on tree growth, which has not been considered before.
Recently, tree-ring researchers of “Extreme Climate Event and Impacts Group” (EXCEIS) from the Institute of Earth Environment, Chinese Academy of Sciences (IEE) studied the non-summer (previous September to current May) hydrothermal condition variations from 1830 to 2017 in the north subtropical China by analyzing the radial growth of Pinus henryi Mast.
The study was published in Trees on November 27.
They found that non-summer hydrothermal condition was the limiting factor of tree growth in the study area. A relatively cold-wet hydrothermal pattern generally favored high growth of trees in 1848-1850, 1893-1898, 1907-1915, 1962-1965 and 1968-1972, whereas a warm-dry climate in 1872-1879, 1923-1931 and 1990-2003 caused unfavorable conditions and led to low tree growth. The current decade is in the process from a warm-dry to a cold-wet non-summer, showing an increasing carbon sequestration potential in the study area.
The study highlighted that the non-summer hydrothermal variations in north subtropical China were influenced by the El Ni？o–Southern Oscillation (ENSO) and sunspot activity at high frequencies, but were influenced by the synergistic effects of the Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO) at low frequencies. It also emphasized that AMO mainly regulated precipitation variability, whereas PDO had a more pronounced effect on temperature variability.
Contact: Bai Jie, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China. Email: baijie@ieecas.cn
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