Age and radial growth pattern of four tree species in a subtropical forest of China

Subtropical forests are usually composed of many tree species. Knowledge of the age and radial growth variation of the dominant tree species is useful for understanding forest dynamics and community structure and function. The aims of this study are to explore whether there are identifiable annual growth rings in the main tree species and to examine the growth characteristics within and among the species in Mount Gutian subtropical forest of China. The results showed that four out of eight tree species from which samples were collected had visible and cross-datable rings. There were no stable relationships between the age and diameter for these subtropical trees. Significant differences existed in radial growth rate within and among the four species, suggesting a high spatial heterogeneity in the mixed-species subtropical forest. The common pattern in age distribution of multiple species suggests a stand-wide disturbance occurring around the 1960s. It is interesting to note that the growth rate at the same age intervals was different for trees younger than 40 years of age and older than 40 years of age, suggesting a change in climate or forest structure in the two time periods. The results obtained from this study help understand the growth dynamics in other subtropical forests having these tree species.