Tree growth responses across environmental gradients in northwestern Argentina: relationships from a dendrochronology view

FERRERO, M.E.; R. VILLALBA

Bariloche, Argentina

Congreso; VI Southern Connection Congress; 2010

U.N. Comahue, CONICET, INTA

In subtropical northwestern Argentina, forests develop from xeric environments in the lowlands through different mesic formations to humid and cold forests at the Yungas treeline.Tree–ring chronologies covering most of environments in this region (22–28° S; 64–65.30° W) were analyzed: 10 chronologies of Juglans australis, 6 Cedrela lilloi, 3 Alnus acuminata and 1 Schinopsis lorentzii. Chronologies were compared with climatic records to determine the factors influencing tree growth. Cluster analyses were conducted to group the chronologies according to their degree of association, which were also evaluated using Pearson correlation coefficient.Cluster analysis separates low (Schinopsis–Juglans) from high–elevation chronologies. Within higher sites cluster discriminate by species: Cedrela and Alnus chronologies form an independent group from the Juglans ones. At species level, subgroups are arranged according to similarities in climate responses; for Juglans, two groups related to temperature and precipitation sensitive sites were recorded. For Cedrela and Alnus, sites were grouped according to water availability.Results suggest that climate is the main factor controlling tree growth at regional scale. In mesic environments, differences in tree–ring patterns are related to the “climatic window” of each species which results in different responses to climate.