Southwest China, including Yunnan Province, is prone to severe droughts by failures of summer monsoon precipitation. Despite the great potential for dendroclimatological studies in Yunnan, there have been very few attempts for tree-ring derived climate reconstructions in the central and southern parts of Yunnan, especially in the subtropics.
In a study published in Palaeogeography, Palaeoclimatology, Palaeoecology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) and their collaborators tried to gain insights into hydroclimate variability in central Yunnan Province. They constructed a tree ring-width chronology of Tsuga dumosa, one of the oldest tree species in the Wuliang Mountain area and has previously been found suitable to reconstruct hydrolimate variability.
Correlations analyses indicated that moisture availability during the spring-to-early summer season was the key factor that limited tree growth of T. dumosa in the Wuliang Mountain. The radial growth of T. dumosa exhibited a negative relationship with temperature, especially in April, prior to the rainy season. Low precipitation and humidity during March–April reduced radial growth of T. dumosa.
The researchers reconstructed the March–June Standardized Precipitation-Evapotranspiration Index (SPEI) for the period from 1826 to 2020 CE, by using a well-calibrated regression model. The reconstructed March–June SPEI series revealed drought fluctuations at both inter-annual and inter-decadal scales, along with an increased occurrence of extreme dry/wet events in recent decades.
Moreover, the reconstruction identified 11 years of extreme drought, with the longest recorded dry and wet periods being 1953–1963 and 1988–2004, respectively. The drought reconstruction series showed high frequency cycle of 2–8 years. The reconstruction also showed a higher frequency of extreme dry/wet events after the 1960s , which was not found in other parts of Yunnan.
"Our study highlights the dendroclimatic potential of conifer tree species growing in subtropical regions and their ability to capture regional hydroclimate signals," said FAN Zexin of XTBG.
Contact
FAN Zexin Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
E-mail: fanzexin@xtbg.org.cn
First published: 8 August 2023
