History of High Mountain Forests of Polylepis Tarapacana at the Bolivian Central Andes

Graz

2006

4 Abb., 2 Tab., 16 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

13342

200140983

In this paper we have investigated the dendroclimatological history of Polylepis tarapacana (queñoa), a small tree growing in the Bolivian Altiplano and adjacent areas of Peru, Chile and Argentina (16-22°S) between 4000 and 5200 m elevation. Dendrochronological samples were collected on the slopes of the volcanoes: Sajama and Caquella. Presently, the chronologies range between 98 and 705 years in length, and represent the highest tree-ring records worldwide. In order to determine the climatic variables controlling P. tarapacana growth, interannual variations in tree growth were compared with regional records of precipitation and temperature. Correlation functions indicate that the radial growth of P. tarapacana is infl uenced by precipitation during the summer previous to the ring formation. In the sampling sites, precipitation explains around 50 % of the total variance in growth. Summer temperatures, which increase evapo-transpiration and reduce soil water supply, are negatively correlated with tree growth. These records offer the unique opportunity for reconstructing precipitation variations across the Altiplano during the past 5 - 7 centuries.