Effects of tree mortality on the spatial patterns and interspecific associations of plant species in a Quercus aliena var. acuteserrata forest in Baotianman, Henan, China

Abstract

Aims Tree mortality is an important ecological process in forest ecosystems. The aims of this study were to determine how tree mortality influences the spatial patterns and interspecific associations of plant species, and what are the causes of tree mortality in a 1 hm 2 permanent plot in Baotianman National Nature Reserve, Nanyang City, Henan Province. Methods We conducted field investigations in the plot and used spatial point pattern analysis to examine the spatial patterns and interspecific associations of 17 species prior to and following mortality. Important findings (1) Most of the species in the study plot showed an aggregated distribution both pre-and post-mortality. However, the number of species showing aggregated distribution decreased and the number of species showing random distribution increased following the mortality event. (2) Most species were positively associated with Quercus aliena var. acuteserrata both pre-and post-mortality, while some had no apparent association. Following tree mortality, on fine scales, the number of species with positive associations increased, and the number of species with negative associations decreased. (3) Tree mortality was in consistency with the random death hypothesis. The interspecific associations of four species with Q. aliena var. acuteserrata completely changed following death. For most species, the spatial patterns and the interspecific association with Q. aliena var. acuteserrata either changed at minor scales or did not change. The variations in spatial patterns or interspecific associations were inconsistent among species. (4) The dead trees of Q. aliena var. acuteserrata were significantly