Effects of enrichmemt planting with native tree species on bacterial community structure and potential impact on Eucalyptus plantations in southern China

Yuxing Xu,Lichao Wu,Apeng Du,Wankuan Zhu,Zhichao Wang,Chao Li

doi:10.1007/s11676-021-01433-6

Abstract

Multi-generational planting of Eucalyptus species degrades soil quality but the introduction of legumes can improve soil fertility and microbial diversity. However, the effects of introducing non-legume native tree species on soil nutrients and bacterial community structure remain poorly understood. This study investigated the impacts of the conversion of third generation monoculture Eucalyptus plantations to mixed systems including Eucalyptus urograndis with Cinnamomum camphora (EC) and E. urograndis with Castanopsis hystrix (EH), on soil chemical and biochemical properties and bacterial community structure, diversity and functions. First generation E. urophylla plantations were the control. Results show that planting the third generation Eucalyptus led to a significant decrease in pH, organic matter, nutrient content, enzyme activities (invertin, acid phosphataes, and urease), and bacterial α-diversity compare to the controls. However, the mixed planting showed significant improvement in soil chemical and biochemical attributes and bacterial α-diversity, although the E. urograndis and C. hystrix planting had no improvement. Chloroflexi (oligotrophic bacteria) were significantly enriched in third generation Eucalyptus and Eucalyptus + C. hystrix, while proteobacteria increased significantly in the E. urograndis with C. camphora plantings. The relative abundance of multiple metabolic pathways increased significantly in the third generation Eucalyptus plantations whereas membrane transport-related genes were enriched in soils of the mixed systems. The changes in bacterial community structures in the two mixed systems were driven by diversity, organic matter and acid phosphatase, while bacterial functions were affected by invertase, {mathrm{NO}}_{3}^{-}-N, diversity and urease. These results suggest that the transformation of successive monoculture Eucalyptus plantations into mixed plantations reduces the depletion of soil nutrients and enhances the ecological function of soil microorganisms.

Highlights

Eucalyptus species are widely planted in southern China, and their wood is an important industrial raw material (Gonçalves et al 2013)
The continuous planting of third-generation Eucalyptus (E) and the mixed plantations of E. nurograndis with C. hystrix (EH) significantly reduced soil organic matter (OM), total N, NO−3 -N, and available P compared with the first-generation Eucalyptus plantations (CK) (Table 1, p < 0.05)
This study revealed the effects of multi-generational planting of monoculture Eucalyptusand a mixed approach of Eucalyptus and native species on soil biochemical properties and bacterial community structure and function

Summary

Introduction

Eucalyptus species are widely planted in southern China, and their wood is an important industrial raw material (Gonçalves et al 2013). Large areas were established as monocultures, with multi-generation continuous planting, which has caused numerous ecological and environmental problems, e.g., soil degradation and loss of ecosystem stability (Liu and Li 2010; Xu et al 2020). These problems pose a serious threat to the sustainable management of plantations (Arnold et al 2020) and prompt rethinking what sustainable Eucalyptus management is. Presl. and Castanopsis hystrix Miq., have been introduced into monoculture Eucalyptus plantations due to their excellent wood properties and adaptability to humid and acidic soil (Guo et al 2018; Xu et al 2021)

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Discussion

Conclusion