Inter-annual and intra-annual tree-ring oxygen isotope signals in response to monsoon rainfall in northwestern Thailand

Abstract

We present a new teak ( Tectona grandis L.f.) tree-ring stable oxygen isotope (δ18OTR) chronology from Mae Tuen (MT) site, Tak province, northwestern Thailand at inter-annual (167-year, A.D.1850–2016) and intra-annual (A.D.2006–2016) timescales. The inter-annual δ18OTR chronology showed a significant negative correlation ( r = −0.678, p < 0.01) with the May–October amount of regional rainfall obtained from CRU TS4.03. We established a linear regression model that explained 46.0% of the actual rainfall variance and reconstructed monsoon season rainfall back to A.D.1850. The seasonal variations in moisture conditions were reflected in inter-annual δ18OTR variability. The rainfall amount and δ18O in precipitation (δ18Op) mainly controlled intra-annual variations in teak δ18OTR. These results show that the variation in Thai teak δ18OTR is dominated by rainfall, highlighting the strength of δ18OTR as a monsoon rainfall proxy.

Summer climate information recorded in tree-ring oxygen isotope chronologies from seven locations in the Republic of Korea

“…Such absorption largely depends upon the precipitation during that period. The δ 18 O TR chronologies are therefore greatly influenced by the precipitation during the growing season, and any change in annual precipitation patterns causes variation in the oxygen isotope ratio in the tree rings (Seo et al, 2019;Choi et al, 2020a;Preechamart et al, 2023;Watanabe et al, 2023). Therefore, the isotopes in different trees of the same species exhibit similar patterns of change in the same climate zone, thereby making it possible to use them in climate analysis and establish tree-ring oxygen isotope chronologies (δ 18 O TR chronologies) over extensive areas (Baker et al, 2015;Young et al, 2015;Choi et al, 2020a).…”