Relación clima-crecimiento radial de Polylepis australis en un gradiente altitudinal en las Sierras Grandes de Córdoba, Argentina

Abstract

Altitudinal gradients represent strategic sites for studying the relationships between climate and growth in woody species. Polylepis australis Bitt. is an endemic tree of Central and Northwest Argentina mountains, growing between 900 and 2800 m a. s. l. in the Sierras Grandes of Córdoba. Previous studies found that radial growth changes with elevation, suggesting that different climatic factors regulate growth along the altitudinal distribution. However, the specific growth response to climatic factors remains unknown. The objective of the present study was to evaluate how varies the relationship between the radial growth of P. australis and temperatures and the precipitations along an altitudinal gradient in the Sierras Grandes of Córdoba. Three sampling points were established at 1200, 2100 and 2700 m a. s. l. In winter 2004 and spring 2014, dendrochronological samples were collected and ring-width chronologies were developed at the three altitudes. From the three chronologies obtained it was found that the radial growth decreases with increasing altitude and the intermediate and higher altitudes show similar interannual growth variations that could be associated with a common climatic tree-growth response. To determine the effect of temperatures and precipitations on the radial growth rate of P. australis, correlations were made between climatic chronologies and ring width chronologies. Our results suggested a significant and positive correlation between annual growth and temperatures in the November and March months. At the lower altitudinal level, growth rings were not significantly correlated with climatic variations. The present work constitutes the first dendroclimatic study developed on P. australis woodlands.

Altitudinal gradients represent strategic sites for studying the relationships between climate and growth in woody species. Polylepis australis Bi�. is an endemic tree of Central and Northwest Argentina mountains, growing between 900 and 2800 m a. s. l. in the Sierras Grandes of Córdoba. Previous studies found that radial growth changes with elevation, suggesting that different climatic factors regulate growth along the altitudinal distribution. However, the specific growth response to climatic factors remains unknown. The objective of the present study was to evaluate how varies the relationship between the radial growth of P. australis and temperatures and the precipitations along an altitudinal gradient in the Sierras Grandes of Córdoba. Three sampling points were established at 1200, 2100 and 2700 m a. s. l. In winter 2004 and spring 2014, dendrochronological samples were collected and ring-width chronologies were developed at the three altitudes. From the three chronologies obtained it was found that the radial growth decreases with increasing altitude and the intermediate and higher altitudes show similar interannual growth variations that could be associated with a common climatic tree-growth response. To determine the effect of temperatures and precipitations on the radial growth rate of P. australis, correlations were made between climatic chronologies and ring width chronologies. Our results suggested a significant and positive correlation between annual growth and temperatures in the November and March months. At the lower altitudinal level, growth rings were not significantly correlated with climatic variations. The present work constitutes the first dendroclimatic study developed on P. australis woodlands.