Pinus latteri, commonly known as Tenasserim pine or two-needle pine, is widely distributed across the tropics of Southeast Asia. Its growth is highly sensitive to year-to-year hydroclimate variabilities. Tree-ring data of this species serve as climate proxies and provide the opportunity for paleoclimate reconstruction.
Using tree-ring width data of Pinus latteri from three sites in southern Laos, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) developed a new regional composite chronology and reconstructed the hydroclimatic variability during 1885–2019. They showed that tree-ring widths of Pinus latteri in southern Laos were an effective tool for studying long-term hydroclimatic variability in the region.
Related results were published in Palaeogeography, Palaeoclimatology, Palaeoecology.
They found that the ring widths of the trees were negatively correlated with temperature and positively correlated with precipitation, self-calibrated Palmer Drought Severity Index (scPDSI), and Standardized Precipitation Evapotranspiration Index (SPEI) in both dry and wet seasons. Tree-ring growth was mainly influenced by moisture conditions during the dry and wet seasons, and had a significant positive correlation with SPEI from March to August.
The March–August drought reconstruction in southern Laos showed an increasing frequency of extreme dry and wet years since the 1970s. It identified several dry and wet episodes in southern Laos over the past 135 years. Notably, prolonged droughts occurred on a decadal scale during 1896–1905, 1925–1936, 1952–1971, and 1979–1988, possibly linked to ENSO activities.
Moreover, it was also found that hydroclimatic changes in southern Laos were negatively correlated with sea surface temperatures in the tropical Pacific and Indian Oceans, suggesting that these changes were driven by large-scale ocean–atmosphere circulations.
“Our findings suggest that the rising occurrence of extreme drought events, exacerbated by global warming, may lead to more intense meteorological droughts with adverse effects on society and forest ecosystems,” said FAN Zexin, a corresponding author of the study.
The researchers recommended expanding the tree-ring network to enhance spatial and temporal coverage of climate proxies in Southeast Asia regions.
Published: 8 November 2024
