Biogeographic, Atmospheric, and Climatic Factors Influencing Tree Growth in Mediterranean Aleppo Pine Forests

• Main Authors: J. Julio Camarero, Raúl Sánchez-Salguero, Montserrat Ribas, Ramzi Touchan, Laia Andreu-Hayles, Isabel Dorado-Liñán, David M. Meko, Emilia Gutiérrez
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Forests
• Subjects: dendroecology; drought; Pinus halepensis; radial growth; VS-Lite model
• Online Access: https://www.mdpi.com/1999-4907/11/7/736

There is a lack of knowledge on how tree species respond to climatic constraints like water shortages and related atmospheric patterns across broad spatial and temporal scales. These assessments are needed to project which populations will better tolerate or respond to global warming across the tree species distribution range. Warmer and drier conditions have been forecasted for the Mediterranean Basin, where Aleppo pine (<i>Pinus halepensis </i>Mill.) is the most widely distributed conifer in dry sites. This species shows plastic growth responses to climate, being particularly sensitive to drought. We evaluated how 32 Aleppo pine forests responded to climate and atmospheric patterns during the second half of the 20th century by using dendrochronology. Climatic constraints of radial growth were inferred by fitting the Vaganov‒Shashkin (VS-Lite) growth model. Aleppo pine growth decreased and showed the highest common coherence among trees in dry, continental sites, such as those situated in southeastern and eastern inland Spain and Algeria. Growth increased in wetter sites. Tree growth was enhanced by prior wet winter conditions and cool and wet spring conditions, whilst warm summers were associated with decreased growth. The relationships between site ring-width chronologies were spatially structured, which explains why Aleppo pine growth was distinctly linked to indices describing atmospheric circulation patterns, showing a stronger influence in western sites (Western Mediterranean Oscillation and Northern Atlantic Oscillation). The climatic constraints of growth and their biogeographical variability were captured by the VS-Lite model, with better fits in dry and continental sites, showing strong growth coherence between trees and climatic limitations of growth. Further research using similar broad-scale approaches to climate–growth relationships and in drought-prone regions deserves more attention.