Recent studies indicate that tropical forests worldwide are highly sensitive to extreme events like El Niño and to deforestation-driven reductions in rainfall [Trenberth and Hoar, 1997]. Although a number of proxies exist for reconstructing tropical climate (corals, ice cores, speleothems and varved sediments), there remains a shortage of sub-annually resolved proxies from terrestrial environments, which are key for understanding climate and carbon cycling dynamics. Because trees are widely distributed in the tropics, often grow throughout the year and can be long lived, they may be used as proxies for reconstructing multi-century climate records from the terrestrial tropics. However, dendrochronology studies based on ring counting are few in the tropics [Whitmore, 1990] (Figure 1), although selected species are appropriate for tree ring analysis [Fahn et al., 1981]. The general absence of anatomically distinct annual growth rings, discontinuous banding and false rings in many tropical tree species make accurate age-modelling difficult [Stahle, 1999]. Radiocarbon (14C) measurements can be used to assess the annual nature of growth rings [Biondi and Fessenden, 1999] and estimate the age and average growth rates of tropical trees [Poussart et al., 2004; Poussart and Schrag, 2005]. However, uncertainties associated with soil respiration, internal carbohydrate transfer and species-specific effects can limit the application of 14C dating [Worbes and Junk, 1989]. Alternatively, dendrometer bands [DaSilva et al., 2002], repeated diameter measurements [Lieberman and Lieberman, 1987] and cambium wounding methods [Mariaux, 1967] may be used although their application is restricted to the last couple of decades. Analysis of tropical wood chemistry may bare seasonal signatures of cambium activity. Studies in Indonesia [Poussart et al., 2004] and Thailand [Poussart and Schrag, 2005] (Figure 1) demonstrate that the generation of replicated sub-annual δ18O and δ13C records from ringless tropical trees is possible over several decades. However, because hydrological patterns are spatially heterogeneous, large sample sets are required to capture climatically robust signals. Cellulose sample preparation remains labour intensive and record replication is challenging. Here, we show how seasonally resolved trace element records measured on tropical ringless trees, like temperate forest tree ring records, can serve as proxies for dating and reconstructing growth and climate histories. The technique relies on synchrotron X-ray microanalysis and allows more versatility in sample state, including analyses of liquid and hydrated solids such as wood. The analysis can be done in air without a requirement for sample pre-treatment or coating. Using this approach, large numbers of dendrochemical records can be generated and replicated rapidly helping to fill a critical gap in climate time series from the terrestrial tropics.
 Trees uptake trace elements via their roots, foliage and bark [Clarkson, 1984]. The fluxes of trace elements are regulated by their bioavailability within the soil matrix as well as their particular metabolic function during growth [Martin et al., 2003]. Elements distribution in the xylem varies according to external factors such as climate and site specific characteristics and internal factors such as tree age, pathway dependent delivery time between uptake and incorporation, heartwood/sapwood (H/S) transfer and wood density [Watmough, 1997].
 A number of dendrochemical studies report historical changes in soil and atmospheric chemistry as well as climate [Watmough, 1997]. However, a mechanistic framework for the incorporation of trace elements into trees remains largely incomplete. Observation of radial mobility of certain elements [Martin et al., 2003; Nabais et al., 2001], the existence of species-specific pith-to-cambium concentration gradients along with differences in H/S physiology render some records difficult to interpret. Consequently, recent temperate latitude studies are carefully evaluating such factors and converging on selected species and elements with low radial mobility such as Ca and Zn [Nabais et al., 2001].