Characterization and analysis of climatic signal in chronologies of Fagus sylvatica L. and Quercus robur L. in the central Cantabrian region, Spain

Abstract

In this work, the climatic responses of three beech (Fagus sylvatica L.) and three oak (Quercus robur L.) tree-ring chronologies in the central Cantabrian region, were analyzed. Regional temperature and precipitation data, and the climatic teleconnection indices of the North Atlantic Oscillation (NAO), were used as climatic predictors. Very similar interannual ring-width variability among chronologies of different species and localities was displayed. Chronologies of the same species and similar altitudes showed the highest cross-correlations, which were significant at widest timescales. Periodic signals of a variety of frequencies that coincided with signals characteristic of NAO indices, were discovered in the chronologies. Between 52 to 64% of growth variance was explained by regional climate, while 13 to 27% was related to monthly NAO indices. High summer temperatures in the year prior to ring formation and low winter temperatures limited beech growth at altitudes over 700 m. Oak radial growth at lower altitudes was limited by high spring temperatures in the previous year and summer drought in the year the ring was formed. Growth of both species displayed negative relationship with winter NAO indices, in the previous year for beech and in the current year for oak. Moreover, oak exhibited a negative correlation with NAO indices in the late summer of previous year. The obtained results suggest that more exhaustive research, regarding the characterization of radial growth and the analysis of its climatic response along the complete Cantabrian region, is required.