Dendrochronological Study of the Xeric and Mesic Araucaria araucana Forests of Northern Patagonia: Implications for Ecology and Conservation

Abstract

The identification of the forest structure could give insights of the processes that determine certain aspects of the population dynamics over time. To address this concern in the Araucaria araucana forests of northwestern Patagonia in Argentina, 14 forest stands distributed along a strong precipitation gradient were analyzed. A suite of components of the forest structure were considered in order to determine (1) the relationship between climate and tree growth variability, (2) the age structure of each study site by defining age classes through the tree-ring analysis, (3) the relationship between tree age, tree height, and stem diameter, and (4) sex ratio. Xeric forests were affected significantly and negatively by the temperature of the current growing season, while mesic forests were more affected during winter months. Precipitation showed a positive effect on growth at the beginning of the growing season in all forests. Age distribution in the xeric and mesic environments showed a preponderance of trees between 51 and 300, and 51 and 250 years old, respectively. Broadly, male and female trees were more abundant in xeric and mesic forests, respectively. The tree age-diameter and tree height-diameter relationships were significantly positive in both mesic and xeric environments. Through these elements, some aspects of the A. araucana trees and forests in their natural distribution area were revealed, which consolidate a better understanding of the ecology and dynamics of these endemic forests and provide tools for designing proper conservation strategies.