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 demonstrated1–4 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 microclimate4–6). It is therefore important to ascertain the degree of coherence in the isotope records among different radial directions of a tree disk7,8 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.