Tree–growth responses and relationships with Bermejo streamflow in northwestern Argentina

M. E. FERRERO; R. VILLALBA

Valdivia, Chile

Workshop; Third Annual Science Meeting, IAI CRNII-047 Project, “Documenting, Understanding and Projecting changes in the hydrological cycle in the American Cordillera”; 2010

IAI- InterAmerican Institute for Global Change Research

In subtropical northwestern Argentina, forests develop under a wide range of environmental and climatic conditions. The xeric Chaco forests of the lowlands grade progressively through different mesic formations to humid and cold forests at the Yungas treeline. We analyzed 15 tree–ring chronologies covering most of the environments within this subtropical region (22°–28°S; 64°–65.30°W). Chronologies were compared with precipitation and temperature records from the nearby meteorological stations to determine climatic factors influencing tree growth. Cluster and Principal Components Analyses were used to group the chronologies according to their degree of association. Our results suggest that climate is the main factor controlling tree growth at the regional scale: species such as Juglans and Schinopsis show similar variations in growth at sites with low precipitation.  In mesic environments, differences in tree–ring patterns are related to the “climatic window” of each species which results in different responses to climate. The coordination among growth responses to climate might be useful when using tree-rings as proxies to reconstruct hidrological events related to precipitation. In addition, we explore the potential of these biological records to associate to northern Argentina Bermejo basin stream flow.