Multi-century lake area changes in the Southern Altiplano: a tree-ring-based reconstruction

MORALES, MS; CARILLA, J; GRAU, HR; VILLALBA, R

CLIMATE OF THE PAST

COPERNICUS PUBLICATIONS

Lugar: Gottingen; Año: 2015 vol. 11 p. 1139 - 1152

1814-9324

High-elevation endorreic lakes in the Southern Altiplano of South America representa major source of local biodiversity. Size and depth of wetlands in Northwest Argentine(NWA) and Southwest Bolivia (SWB) have shown to be very sensitive to basin5 hidrological balances, and consequently, very vulnerable to deleterious eects fromclimate changes. The management of these water resources requires a comprehensiveknowledge of their natural variability over multiple time scales. In this study wepresent a multi-century reconstruction of past lake-area fluctuations in the NWA andSWB, inferred from Polylepis tarapacana tree-ring records. Between 1975 and 200910 interannual lake area fluctuations from nine lakes were quantified based on Landsatsatellite images. A composite P. tarapacana tree-ring chronology was developed. Correlationsanalyses were performed to screen potential predictor tree-ring chronologiesfor reconstruction models. Inter-annual lake area fluctuations were positively correlatedwith inter-annual variations of the radial growth of P. tarapacana. A tree-ring chronol15ogy (601 years long) was use as predictor, in a regression model, to reconstruct theannual (January?December) mean lake area from nine endorreic lakes. The chronologycaptures 60% of the total variance in lake-area fluctuations and shows adequatelevels of cross-validation. The twentieth century was unusual in the long-term contextprovided by the reconstruction; a persistent negative trend in lake area is clear in the20 reconstruction during the past century and is consistent with glacier retreat and otherclimate proxies from the Altiplano and tropical Andes. These results provide a baselinefor the historical range of variability in lake fluctuations, and thus should be consideredfor the management of biodiversity and water resources in the region, particularly inrelation to future XXI century climate scenarios.