Tree-Ring Patterns and Growth Response of Abies jaliscana to Climate along Elevational Gradients in the Mountains of Western Jalisco, Mexico

Abstract

Jalisco fir (Abies jaliscana) is an endemic tree with restricted distribution, and is considered a Pliocene relict inhabiting the cloud montane forests in the humid-temperate upper zone of western Jalisco Mountains. Despite its ecological importance, to date, there are no studies for this taxon aimed to understand its vulnerability to regional climate variability. We used dendrochronological techniques to investigate tree-ring patterns and the effects of climate variability on the radial growth of Jalisco fir through its elevational range in both southern and northern aspects. We developed tree-ring series that ranged in length from 79 to 152 years. High-elevation trees (2400 m.a.s.l.) showed higher annual radial growth compared to those present in low-elevation sites. Over the last 150 years, Abies jaliscana trees have had higher annual radial growth rates compared to those exhibited by other Abies species. Both winter and early spring precipitation are the main factors determining the growth rates at all the elevation sites for both aspects. In the cold season, mean maximum temperature negatively affected ring-width growth at most of the elevation zones except for two study sites. We conclude that the radial growth of A. jaliscana appears to be smaller during lower rainfall periods in the dry seasons (winter and early spring), and A. jaliscana annual radial growth responds differently to regional climate variability along the elevational gradient and mountain aspects.