Aggregation distributions across stand age in provenances of Cunninghamia lanceolata (Lamb.) Hook

Abstract It is particularly important to select the provenance with better adaptability in the context of the counteracting potential adverse effects of climate change. However, the growth environment of trees and the length of breeding cycle determine the uncertainty of early selection. Thereby, it is advisable to provide information for provenance selection by analyzing the relationship between young, middle and mature forests. Chinese fir(Cunninghamia lanceolata (Lamb.) Hook.) is an evergreen coniferous tree species with rapid growth and high-quality timber, and it is an important reforestation and commercial tree species in South China. The provenance experimental forests of Chinese fir in Jiangxi and Guangxi were taken as the test object, the growth survey went by three stages of growth: young, middle and mature ages. The linear mixed model was used to evaluate the differentiation of different forest stage provenances in terms of growth. K-medoids clustering algorithm was used to group provenances, the geographical distribution characteristics of Chinese fir were evaluated based on the major groups, and the risk of early selection and the genetic gain of excellent provenances were calculated. The highest total variability was explained by the genotype effect (G) in the young, middle-aged and mature forest stage, the influence of genotype increased through time, while the influence of site was reduced and the G×E interaction changed in a small range. The differences in heritability were similar between young and middle-aged forests, but the heritability of growth traits was higher at Jiangxi than Guangxi in the mature forest stage. The provenances with excellent productivity Chinese fir showed aggregation distribution at the mature forest stage, and the provenances with worst growth were mainly distributed in the northern marginal production area.