Climate change is causing changes in tree species performance and distribution, impacting breeding programme effectiveness. Our aim was to analyse the effects of provenance and climatic factorson the annual ring density of Masson pine (Pinus massoniana Lamb.) at different experimental sites and potential breeding strategies that may be developed in response to future climate change. The study trees represented provenances originating from the western, east-central, northern, and southern regions of P. massoniana distribution in China. The wood density differed significantly among provenances. A multisite variance analysis test showed that the type B correlation coefficients for ring density at the two sites studied were less than 0.8, indicating an interaction effect of genotype by environment (G×E) on tree ring density. Climatic factors directly affected the wood density properties. At Chun’an (CA), the maximum latewood density (MXD) and minimum earlywood density (MND) were positively correlated with absolute maximum temperatures in August and May of the current growing season, respectively. At Taizi Mountain (TZS), MXD was significantly positively correlated with absolute maximum temperature in September ofthe current year and significantly negatively correlated with precipitation in June. MND was significantly positively correlated with absolute maximum temperature in May of the current year and significantly negatively correlated with precipitation in April. The climatic effects on P. massoniana wood density differed among seed-source origins. This study showed that ring density characteristics differed significantly among provenances, and provenance selection could promote wood density. MXD and MND exhibited significant genotype-by-environment interaction effects, and significant correlations were found between ring density and temperature, and precipitation conditions. These findings suggest that climatic factors and site conditionsin addition to genetics could be strong drivers of wood density variation, and/or that wood density is a highly plastic trait.
