Tree-ring δ18O climate signals vary among tree functional types in South Asian tropical moist forests uri icon

abstract

  • We present the first annually resolved and statistically reliable tree-ring delta O-18 (delta O-18(T)) chronologies for the three South Asian tropical moist forest tree species (Chukrasia tabularis A. Juss., Toona ciliata M. Roem., and Lagerstroemia speciosa Roxb.) which differ in their shade tolerance and resistance to water stress. We found significantly higher mean delta(18)O(T )values in light-demanding T. ciliata than in intermediate shade tolerant C. tabularis and shade tolerant L. speciosa (p < 0.001). delta O-18 in C. tabularis was mainly influenced by pre-monsoon vapor pressure deficit (VPD; r =-0.54, p < 0.01) and post monsoon maximum temperature (T-max) (r = 0.52, p < 0.01). delta O-18(T) in T. ciliata was strongly negatively correlated with a dry season drought index PDSI (r =0.65, p < 0.001) and VPD (r = 0.58, p < 0.001). Pre-monsoon T-max was strongly positively linked with delta O-18. in L. speciosa (r = 0.65, p < 0.001), indicating that climatic influences on delta O-18(T). are species-specific and vary among tree functional types. Although there was a week correlation between local precipitation and delta O-18(T) in our studied species, we found a strong correlation between delta O-18. and precipitation at a larger spatial scale. Linear mixed effect models revealed that multiple factors improved model performance only in C tabularis, yielding the best model, which combined VPD and T-max. The top models in T. ciliata and L. speciosa induded only the single factors PDSI and T-max, highlighting that the way C. tabularis interacts with climate is more complex when compared with other two species. Our analyses suggest that stable oxygen isotope composition in tree rings of South Asian tropical moist forest trees are a suitable proxy of local and regional climate variability and are an important tool for understanding the physiological mechanisms associated with the global hydrological cycle. (C) 2020 Elsevier B.V. All rights reserved.

publication date

  • 2021
  • 2020