Dendroclimatic potential of Polylepis pepei in the Tropical Andes (Peru, Bolivia)

in cooperation with IRD
 

This paper investigates the dendroclimatological potential of Polylepis pepei. This species is endemic and widely distributed in the tropical Andes, where it forms an upper tree line above the closed mountain forest belt from approximately 3500 m to 4500 m asl. In Peru, P. pepei trees were sampled in Vilcabamba and Vilcanota mountain chains close to Urubamba city and in Bolivia in Zongo valley close to La Paz city. Chronologies that extend over the 20th century show moderate values of mean sensitivity, common variance and signal to noise ratio.
 



Correlation and response function analyses revealed significant positive correlations between temperature during austral summer in the previous and the growth year and radial growth in Peru. In Bolivia, significant relationships were observed between temperature at the beginning of the austral summer and tree growth. Relationships with precipitation were much more complex, and were influenced by location and the nature of the slope deposit (moraine or scree slope) on which the trees grew. Positive relationships were observed between precipitation in the previous year and in the growth year and radial growth at the beginning of the rainy season in Peru on moraine deposit. In Bolivia positive relationships were observed with precipitation during the dry season for trees growing either on moraine or on scree slopes. However significant relationship was only observed between tree growth on scree slope and precipitation during the rainy season. This species appears relevant for future climate reconstructions.

 


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