Effects of neighborhood interaction on tree growth in a temperate forest following selection harvesting

Abstract

Selection harvesting is a common silvicultural practice in uneven-aged natural forests. Understanding the complex response of individual trees to forest harvesting is of great importance to clearly assess how forest ecosystems respond to future management. While tree growth dynamics following forest harvesting have been well documented at the stand level, at the individual level, how neighborhood interaction affects tree growth after forest harvesting has received little attention. Based on the data from four1-ha permanent forest plots with mapped trees and different harvesting intensities in Northeastern China, the effects of neighborhood interaction on tree growth of 1,108 focal trees were analyzed four years after forest harvesting. Neighborhood interaction was quantified by several indices, considering both crowding and biological dissimilarity (based on taxonomy, phylogeny, and functional traits) between neighboring trees. Additionally, we tested whether the effects of the neighborhood interaction on tree growth might differ across harvesting intensities. Our results found that selection harvesting significantly increased tree growth and biological dissimilarity but decreased crowding at the individual tree level. Focal tree growth decreased by 12.9%, 9.7%, and 7.9% as a result of neighborhood interaction based on taxonomic, phylogenetic, and multi-trait dissimilarity, respectively. Neighborhood interaction based on maximum height appeared to be the most important determinant of tree growth among the four traits examined (i.e., leaf dry mass per area; leaf nitrogen concentration; wood density; and maximum height), and its effect was much stronger than that of the multi-trait dissimilarity index. Moreover, among the neighborhood interaction indices, increasing neighborhood crowding reduced tree growth and there was a significant negative crowding effect at medium to high harvesting intensities (40%∼60% basal area removed) on tree growth. Our study expands our understanding of the relationship between neighborhood interaction and tree growth by identifying crowding and biological dissimilarity as important neighborhood indices for post-harvest tree growth.

Keywords

• Selection harvesting
• Functional traits
• hierarchical Bayes
• Neighborhood interaction
• Temperate forests
• Tree competition