Growth Variations of Tree Saplings in Relation to Species Diversity and Functional Traits in a Tree Diversity Pot Experiment

Jingjun Yang,Wenhua Xiang,Xinrong Hui,Shuai Ouyang,Pifeng Lei

doi:10.3390/f9070380

Abstract

Despite the accumulating evidence of the beneficial effects of diverse mixed species forests on ecosystem functioning and services, foresters in subtropical forest cultivation in China still prefer easily managed monocultures, which is also due to the complexity of mixed forests and the unknown underlying mechanisms related to relationships between biodiversity and forest growth. In a designed pot experiment, we selected two early-successional tree species (Pinus massoniana Lamb., Liquidambar formosana Hance.) and two late-successional tree species (Schima superba Champ., Elaeocarpus decipiens Hemsl.) and planted four saplings in one pot with regard to tree species diversity (monoculture, two species and four species mixtures), each combination replicated four times. In this three-year duration experiment, the effect of tree species diversity, tree identity, and functional traits on sapling growth (tree height, ground diameter, crown projection area), were analyzed. The results showed that the increments of ground diameter and crown projection area increased with tree species richness, whereas the mean tree height increment showed the opposite effect. This growth variation was species specific and related to functional traits (early or late succession), as the increments of the early successional tree species (P. massoniana Lamb. and L. formosana Hance.) had a positive correlation with tree species richness, while the late successional tree species (E. decipiens Hemsl. and S. superba Champ.) showed negative effects. In addition, our study provided evidence for the allometric differences between mixtures and monocultures, which have an important reference value on mixed-species forests.

Highlights

Biodiversity is an ancient issue, even derived earlier than ecology
Cumulative increment of diameter increased slightly with increasing species richness at the pot Cumulative of diameter increased slightly with different increasing species richness at the level, increment no significant differences were detected among species diversity levels pot(Figure level, no significant differences were detected among different species diversity levels
We did not find a consistent pattern between tree growth and species richness (p > 0.05)

Summary

Introduction

Darwin [1] pointed out that grass in a mixture will gain more hay than monoculture. Over the one hundred years, ecologists devoted themselves to the research of the relationships between diversity and productivity. Many studies were conducted on grass ecosystems [2,3,4,5], and most of the results revealed over-yielding (i.e., a higher biomass or production in a mixture than in the corresponding monocultures), some of those showed a negative or no correlation relationship. Forests 2018, 9, 380 and more and more ecologists have begun to study the effects of biodiversity on ecosystem functioning (BEF) in the forest ecosystem. Many manipulated biodiversity experimental sites have been established and evidence of positive BEF is accumulating. People still adopt monoculture in plantation cultivation [7]

Methods

Results

Conclusion