South American tree rings as climate proxy records

BONINSEGNA, J.A..; J. ARGOLLO; J.C. ARAVENA ; J. BARICHIVICH; D. CHRISTIE; M.E. FERRERO , A. LARA ; C. LE QUESNE; B. H. LUCKMAN; M. MASIOKAS; M. MORALES; J.M. OLIVEIRA,, F. ROIG ; A. SRUR ., AND R. VILLALBA

PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY

Elsevier

Año: 2008

0031-0182

Recent years have seen a consolidation and expansion of tree ring sample collection across South America. Most collections are concentrated in the temperate forests along the eastern and western slopes of the Southern Andes (32°S to 55° S).  However, important advances in the reconnaissance and collection of new woody species usefully for dendrochronology have recently been documented. The development of chronologies in tropical and subtropical arid regions of the Cordillera and in particular the Altiplano, is probably one of the most important advances in the South American dendrochronology. Polylepis tarapacana, growing at 4000-4500 m elevation on the Altiplano, has yielded more than ten chronologies spanning over the past 700yrs. These records are highly correlated with seasonal variations in climate, particularly total summer (December to March) precipitation and temperature. The development of chronologies in the humid subtropics and tropics remains a major challenge. The number of tree-ring chronologies built up using species from these regions is rather low. The recognition of strong climate signals in tree-rings from Cedrela species provides a unique opportunity to develop a tree-ring network in subtropical and tropical South America. The future of dendroclimatology in South American tropical regions is perceived as extremely promising. Reconstructions of temperature, rainfall, streamflow, snow, and regional atmospheric circulation based in ring width, density and stable isotopes, have been conducted using tree ring chronologies from subtropical and temperate forests. These chronologies were also used in studies relating South American tree ring proxies with high-resolution proxies from other continents or analyzing past changes of the atmospheric circulation, particularly those related to solar forcing. The comparison of climatic reconstructions based on tree-rings with projected atmospheric circulation patterns are providing useful bridges between the past and future trends in global climate change, and its implications for human welfare and socio-economic development. Some examples of this bridging are presented in this review. Future research should address the continuing development of long tree-ring chronologies to improve detection of decadal to centennial signals in climatic variations and to distinguish between natural and human-induced climatic changes in South America.  Collaboration among South American countries in training young scholars is crucial to maintain and increase the progress of dendroclimatology  in the region. Initiatives as the IAI and PAGES projects, facilitating the interaction between scientists from the Americas and overseas should be broadened and their long-term continuation assured.