Reduced Temperature Sensitivity of Maximum Latewood Density Formation in High-Elevation Corsican Pines under Recent Warming

Philipp Römer,Frédéric Huneau,Achim Bräuning,Frederick Reinig,Lea Schneider,Ulf Büntgen,Sonja Szymczak,Claudia Hartl,Sébastien Lebre,Jan Esper

doi:10.3390/atmos12070804

Abstract

Maximum latewood density (MXD) measurements from long-lived Black pines (Pinus nigra spp. laricio) growing at the upper treeline in Corsica are one of the few archives to reconstruct southern European summer temperatures at annual resolution back into medieval times. Here, we present a compilation of five MXD chronologies from Corsican pines that contain high-to-low frequency variability between 1168 and 2016 CE and correlate significantly (p < 0.01) with the instrumental April–July and September–October mean temperatures from 1901 to 1980 CE (r = 0.52−0.64). The growth–climate correlations, however, dropped to −0.13 to 0.02 afterward, and scaling the MXD data resulted in a divergence of >1.5 °C between the colder reconstructed and warmer measured temperatures in the early-21st century. Our findings suggest a warming-induced shift from initially temperature-controlled to drought-prone MXD formation, and therefore question the suitability of using Corsican pine MXD data for climate reconstruction.

Highlights

Southern Europe is predicted to experience increasing aridity in the 21st century mainly due to rising temperatures [1,2,3], and the intensity, frequency, and duration of heatwaves and droughts are expected to increase [4,5]
The Corsican MXD data (COR) Maximum latewood density (MXD) compilation consists of 69 radii from 35 pine trees and spans the period 1168–2016 CE, including an increasing number of measurements toward the present (Figure 4)
The age-band datasets more closely meet the requirements for Regional Curve Standardization (RCS) detrending [50,61], as these chronologies are characterized by more balanced replication and age curves

Summary

Introduction

Southern Europe is predicted to experience increasing aridity in the 21st century mainly due to rising temperatures [1,2,3], and the intensity, frequency, and duration of heatwaves and droughts are expected to increase [4,5]. Ancient trees growing under extreme conditions and still preserved in their natural state are difficult to find, dendroclimatic studies in Corsica offer the opportunity to reconstruct southern European climate variability over several centuries [7,8,9]. Located in the central-western Mediterranean region (Figure 1a), Corsica is characterized by strong elevational gradients between the coastal plains and the central mountain massif (Figure 1b). Coastal regions are characterized by typical Mediterranean climate with hot dry summers (June–August) and temperate rainy winters (October–April). The temperature generally decreases by 0.31–0.49 ◦C/100 m and precipitation increases by approx. Precipitation generally increases with altitude, high elevation areas can be subject to severe droughts during summer, especially between July–August. The Corsican mountains can be characterized as xeric in summer and alpine in winter [13]

Methods

Results

Discussion

Conclusion