Dendroclimatological implications of isotope coherence in trees from Kashmir Valley, India

Abstract

Stable isotope ratios of hydrogen, carbon and oxygen in tree cellulose have recently been demonstrated^1–4 as potential palaeoclimatic indicators. A significant long-term objective of isotope dendroclimatology is the reconstruction of the annual climatic record at a given place. Earlier studies focused mainly on spatial correlations, selecting trees from climatically contrasting regions, rather than temporal correlations at a single site. Single-site correlation involves the problem of extracting a relatively weak climate-dependent isotope signal from a number of inherent non-climatic components (for example, isotope variations along the circumference of a single growth ring and inter- and intraspecies variations among trees growing in the same microclimate^4–6). It is therefore important to ascertain the degree of coherence in the isotope records among different radial directions of a tree disk^7,8 and different trees (same and different species) at a single site. Such coherences are demonstrated here based on δD, δ¹³C and δ¹⁸O measurements of individual rings of trees from Kashmir Valley, India.