Responses to subtropical climate in radial growth and wood density of Chinese fir provenances, southern China

Abstract

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is a native tree species endemic to China and produces timber with high economic value. It is essential to select a provenance with more optimal adaptability to counteract the potential adverse effects of climate change. However, only a few dendroecology analyses of the variation in Chinese fir provenance climate response have been performed. Therefore, we obtained radial growth (tree ring width, earlywood width and latewood width) and wood density (earlywood density, latewood density, minimum density and maximum density) chronologies for 52 Chinese fir provenances grown in a common garden plantation in southern China. Tree-ring analysis methods (dendrochronology) were used to quantify the influence of climate on radial growth and wood densities of the Chinese fir provenances over a 32-year period (1981–2013). The results showed that the mean values of ring widths and wood densities were significantly related to latitude and longitude at the seed-source origin, respectively. Our study also confirmed that tree ring width is primarily sensitive to summer temperature, whereas parameter maximum density contains the strongest climate signal about spring precipitation. Along with a positive effect of warm winter (December and January) on radial growths, high temperatures in summer (July to September) had a negative effect on tree ring widths. Furthermore, the maximum density chronologies shared a significant negative response to the current April precipitation. However, our findings demonstrate that there is the greatest differentiation among Chinese fir provenances in the strength of the correlations between climate variables (temperature and precipitation) and tree ring indices. Based on responses to temperature and precipitation, Chinese fir provenances from the continuous China distribution range can be divided into several geographic groups along a longitudinal and latitudinal gradient. In general, our results suggest that in developing models to predict the response of Chinese fir to changing climate, it is necessary to include intraspecific differentiation in acclimation and adaptation to environmental factors.