Coniferous-Broadleaf Mixture Increases Soil Microbial Biomass and Functions Accompanied by Improved Stand Biomass and Litter Production in Subtropical China

Wu Wu,Zhou Zhou,Li Li,Wen Wen,You You,Huang Huang,Zhu Zhu,Qin Qin,Yan Yan

doi:10.3390/f10100879

Abstract

Although the advantages of multi-species plantations over single-species plantations have been widely recognized, the mechanisms driving these advantages remain unclear. In this study, we compared stand biomass, litter production and quality, soil properties, soil microbial community, and functions in a Pinus massoniana Lamb. and Castanopsis hystrix Miq. mixed plantation and their corresponding mono-specific plantations after 34 years afforestation in subtropical China. The results have shown that a coniferous-broadleaf mixture created significantly positive effects on stand biomass, litter production, soil microbial biomass, and activities. Firstly, the tree, shrub and herb biomass, and litter production were significantly higher in the coniferous-broadleaf mixed plantation. Secondly, although the concentrations of soil organic carbon (SOC) and total nitrogen (TN) were lower in the mixed stand, the concentrations of soil microbial biomass carbon (MBC), and nitrogen (MBN), along with MBC-to-SOC and MBN-to-TN ratio, were significantly higher in mixed stands with markedly positive admixing effects. We also found higher carbon source utilization ability and β−1, 4−N−acetylglucosaminidase, urease and acid phosphatase activities in mixed stands compared with the mono-species stands. Our results highlight that establishment of coniferous-broadleaf mixed forests may be a good management practice as coniferous-broadleaf mixture could accumulate higher stand biomass and return more litter, resulting in increasing soil microbial biomass and related functions for the long term in subtropical China.

Highlights

IntroductionForests 2019, 10, 879 monospecific plantations as reported [3]
Planted forests have been rapidly expanding around the world to meet the ever-growing demand for timber and other ecosystem services while avoiding excessive harvesting of natural forests [1,2].Most planted forests are monospecific plantations
We explored stand biomass, litter, soil physicochemical properties, and soil microbial community structure and function in a mixed P. massoniana and C. hystrix plantation and corresponding single species plantations at an age of 34 years in subtropical China

Summary

Introduction

Forests 2019, 10, 879 monospecific plantations as reported [3]. There are serious concerns regarding monospecific plantations, including stand productivity decrease [4], soil quality degradation [5], and serious exotic plant invasion (e.g., Eucalyptus plantations) [6]. Multi-species plantations often have higher biodiversity, higher productivity, and better soil quality than single-species plantations [7,8,9]. Higher productivity in multi-species compared to single-species plantations can only be expected when species interactions in the multi-species plantations increase the efficiency of resource use or one species increases the supply of a resource [10]. Interactions between species growing in mixtures, e.g., competition, competitive reduction, and facilitation [11] are often dynamic, changing through space and time as resource availability or climatic conditions change [12,13]

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Conclusion