Functional and phylogenetic structures of woody plants in broad-leaved Korean pine mixed forest in Changbai Mountains, Jilin, China

Abstract

Studies on the evolutionary and functional similarity of species can provide new insights into the mechanisms of community assembly, a well-known and important part of community ecology. We measured six functional traits of 50 woody species(wood density, maximum plant height, leaf area, specific leaf area, and leaf nitrogen and phosphorus contents) in a well-mapped 25 hm2 broad-leaved Korean pine mixed forest plot in Changbai Moutains, Jilin Province, China, and tested the phylogenetic signals of these traits. Next, we calculated the functional and phylogenetic structures using a nearest taxon index(NTI) to examine the underlying ecological processes at different spatial scales(10, 20, 40, 60, 80 and 100 m). We found(1) all six functional traits showed significant phylogenetic signals, suggesting close related species have similar ecological characteristics;(2) the functional structure of individual traits showed strong scale dependency. At fine scales, leaf area and maximum plant height were clustered while wood density, leaf phosphorus content, leaf nitrogen content and specific leaf area were overdispersed. At larger scales, most traits showed functional overdispersion or random;(3) the functional and phylogenetic structures differed with spatial scale. At fine scales( 40 m), phylogenetic and functional structures were overdispersed, indicating strong effects of competitive exclusion. At larger scales, phylogenetic and functional structures were random, because of the effects of opposing non-neutral processes. The study of functional and phylogenetic structures at different spatial scales reflects the important roles of non-neutral processes in maintaining diversity in this forest.