Age effects on the climatic signal inAraucaria araucanafrom xeric sites in Patagonia, Argentina

Abstract

Background: At different cambial ages, trees experience changes in their structure and interactions with environmental conditions. Reciprocal mechanisms between tree age and physical resources, photosynthetic rates, and xylem production may influence hydraulic resistance and plant water stress. However, it is yet uncertain how these mechanisms are associated with changes in growth sensitivity to biophysical drivers, especially climate. Aim: To establish age-associated climate -growth relationships in growth rings of Araucaria araucana trees from the temperate xeric zones of northern Patagonia, Argentina. Methods: We analysed the growth in 211 A. araucana trees from four sampling sites, in three age classes: young (≤120 years), mature (121-275 years), and old (≥276 years). We explored the correlations between the signal strength of tree growth and climate, based on comparisons between each age-class chronology and monthly mean surface air temperature, total precipitation, and the Southern Annular Mode (SAM) index. Results: The young trees showed higher correlations when their growth was compared with precipitation, air temperature, and the SAM index during austral spring and summer months of the same year. In contrast, growth in mature and old trees showed higher correlations with summer temperatures of the previous growing season. Conclusions: The sensitivity of the radial-growth response of A. araucana to climate varies with age and is strongest in the rings of young trees.

Sensitivity of pines in Mexico to temperature varies with age

“…Additionally, several recent studies based on tree rings have demonstrated that the response to climate varies with stand age (e.g., Esper et al, 2008;Yu et al, 2008;Rozas et al, 2009;Vieira et al, 2009;Wang et al, 2009;Copenheaver et al, 2011;Hadad et al, 2015). However, Colenutt and Luckman (1991) have suggested that in some cases this duality has not been proven; for example, they found no difference in the response of both young and older Larix lyallii trees to climate.…”

“…While some authors argue that stand age affects the signals of climate that can be observed in plants (e.g., Szeicz and MacDonald, 1994;Carrer and Urbinati, 2004;Linderholm and Linderholm, 2004;Esper et al, 2008;Rozas et al, 2009;Vieira et al, 2009;Hadad et al, 2015), other studies show that climate growth responses are age independent (e.g., Fritts, 1976; Linares et al, 2013;Sun and Liu, 2014). The present study shows that P. cooperi trees from the Sierra Madre Occidental in northern Mexico that are younger than 80 years are more sensitive to the influence of climate than older trees.…”

“…Körner (2006) suggests that the rate of change in radial growth diminish with age in response to changing resource availability. One of the physiological processes that may partially explain how age can control the sensitivity of trees to climate is hydraulic limitation (Carrer and Urbinati, 2004;Yu et al, 2008;Hadad et al, 2015). This restriction may contribute to the limitation of tree growth as the size of the tree increases (Ryan et al, 1997).…”

Sex-related climate sensitivity of Araucaria araucana Patagonian forest-steppe ecotone

“…The ring width was considered as the response variable, sex of individuals as the fixed factor, and sites and stands within sites as random factors. As variables we used those months of precipitation and temperature with the stronger and significant relationship with growth Hadad et al, 2015). The months of precipitation were January of the prior growing period and September of the current period of growth.…”

“…The pehuén is known to be an old tree, reaching ages surpassing 900 years, particularly in forest patches placed on rocky outcrops and surrounded by the dry Patagonian steppe (LaMarche et al, 1979;Hadad et al, 2015). As indicated by previous reports, the inter-annual variability in the ring widths of A. araucana trees reveal a strong dependence to the spring-summer climate conditions during both current and prior period of growth (Villalba et al, 1989;Mundo et al, 2012;Muñoz et al, 2013;Hadad et al, 2015) and at scales of climate forcing it has been observed that growth is lower the higher the spring-summer value of the Southern Annular index Hadad et al, 2015). Moreover, another factor that may have an impact on growth is the incidence of seed production.…”