Diverse growth-climate relationships and response to climate change in Mediterranean pine woodlands in the Iberian Peninsula

Abstract

In the Iberian Peninsula, Western Mediterranean, Pinus pinea woodlands have a great environmental and socio-economic value. There is a need to know the impacts of climate change on the ecology of this species and to develop management options that may improve its sustainability. In this work we provide an assessment of the acclimation capacity and vulnerability of Iberian P. pinea populations under changing climate. These studies also present the first application of dendroecology to growth dynamics in the Southernmost Iberian P. pinea forests. We examined 237 tree-ring chronologies from 12 sites along altitudinal and latitudinal gradients. To characterize the spatiotemporal variability of climate, records from meteorological stations and gridded datasets were used. The growth-climate relationships were analyzed. We assessed the influence of the spatiotemporal variability of climate on tree growth. We observed enhanced growth synchrony among chronologies, an increase in inter-annual ring-width variability, and changes in growth-climate correlations, that can be related to the increased mean temperatures in all regions in recent decades. Local-level differences in climate dynamics are also reflected in the dendroclimatic signals. In the southern (warmer) sites a distinctly reduced response to spring-summer climate was found. This suggests a phenological response of P. pinea to the greater water-stress risk at the lower latitudes in this season. Although limited to Mediterranean-type environments, P. pinea is a plastic species able to growth within a variety of climatic conditions. This can be crucial for its conservation under future climatic contexts, probably characterized by higher temperatures and more limiting water conditions. Trees in the northern (milder) zones may acclimate to a further increase of drought, while the southern populations could further approach, or exceed, an ecological limit, which may threat their sustainability.