Spring-Summer Drought Induces Extremely Low Radial Growth Reactions in North-Tyrrhenian Pinus pinea L.

Sergio Piraino,Fidel Alejandro Roig

doi:10.1590/2179-8087.030318

Sergio Piraino, Fidel Alejandro Roig

Open Access

https://doi.org/10.1590/2179-8087.030318

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Abstract

Abstract Climate projections predict shifts in environmental conditions, with cascade effects on forest growth dynamics. As such, Pinus pinea L., an ecologically important low-elevation Mediterranean tree, can be threatened by drought events. The occurrence of negative stem growth anomalies (“negative pointer years”, or NPY) and its relation to climatic conditions were analyzed, as well as the influence of extreme dry spells upon the species growth. NPY were temporally independent among the analyzed forest stands, likely due to local factors. We observed that NPY depended on dry and hot conditions during the spring-summer period at both sites, while differences in the NPY-climate reflected the species medium term dendroclimatological signal. Extremely dry years directly reduced stem growth rates. Water stress differentially affected growth at each site, likely reflecting local adaptation to droughts. Because of the increasing drought trend expected for the Mediterranean basin, our findings must be considered regarding the conservation and management of these forests.

Highlights

IntroductionClimate change has been increasingly recognized as an influencing factor upon natural systems and human society (Walther et al, 2002)
AND OBJECTIVESDuring the last decades, climate change has been increasingly recognized as an influencing factor upon natural systems and human society (Walther et al, 2002)
Positive pointer years were not computed, since we aimed to reconstruct the temporal occurrence of anomalous growth rates related to water stress, which are most likely expressed as extremely narrow rather than wide ring widths

Summary

Introduction

Climate change has been increasingly recognized as an influencing factor upon natural systems and human society (Walther et al, 2002). In this sense, changing climatic conditions already triggered the growth, survival and distribution of tree species around the globe, inducing forest die-off and decline in tree productivity (Allen et al, 2015; Walther et al, 2002). Dendrochronology is a powerful tool in analyzing the relationship between environmental stress and plant growth (Speer, 2010) This method relies on continuous time series, for example matching annual radial increment with monthly or seasonal climate variables. Extreme growth can reflect the occurrence of climatic anomalies, representing

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