Long-term (1992-2015) dynamics of interspecific associations among tree species in a monsoon evergreen broad-leaved forest in Dinghushan Biosphere Reserve

Monsoon evergreen broad-leaved forest(MEBF) is the climax vegetation type in the subtropics of China, and its structure and species composition have been shifting in the last 23 years. However, we know little about the dynamics of its interspecific associations. Our objective is to investigate the long-term dynamics of overall and pairwise interspecific associations in this forest community. In each community survey of the 1 hm~2 monitoring plot in the Dinghushan Biosphere Reserve, we recorded the species name, diameter at breast height(DBH), and tree height of every tree with DBH ≥ 1 cm. Up to now, seven surveys have occurred, in 1992, 1994, 1999, 2004, 2008, 2010, and 2015. In this study, we selected 29 dominant species according to their importance values, and studied the overall and pairwise interspecific associations by using variance ratio(VR) analysis and Spearman′s rank correlation coefficient test, respectively, on the data from all surveys. From 1992 to 2015, the MEBF communities showed significant positive association; the VR values of all surveys were significantly > 1. However, in this period, the VR value of the community had decreased significantly(R~2=0.93, P