Effect of Root and Mycelia on Fine Root Decomposition and Release of Carbon and Nitrogen Under Artemisia halodendron in a Semi-arid Sandy Grassland in China.

Xinping Liu,Zhong Du,Hongjiao Hu,Yongqing Luo,Li Cheng,Youhan Wang

doi:10.3389/fpls.2021.698054

Abstract

Plant fine root turnover is a continuous process both spatially and temporally, and fine root decomposition is affected by many biotic and abiotic factors. However, the effect of the living roots and the associated mycorrhizal fungal mycelia on fine root decomposition remains unclear. The objective of this study is to explore the influence of these biotic factors on fine root decomposition in a semi-arid ecosystem. In this study, we investigated the effect of fine roots and mycelia on fine root decomposition of a pioneer shrub (Artemisia halodendron) in Horqin sandy land, northeast China, by the ingrowth core method combined with the litterbag method. Litterbags were installed in cores. Results showed that core a allowed the growth of both fine roots and mycelia (treatment R + M), core b only allowed the growth of mycelia (treatment M), and in core c the fine root and mycelia growth were restricted and only bulk soil was present (treatment S). These findings suggest that the process of root decomposition was significantly affected by the living roots and mycelia, and carbon (C) and nitrogen (N) concentration dynamics during root decomposition differed among treatments. Mycelia significantly stimulated the mass loss and C and N release during root decomposition. Treatment R + M significantly stimulated the accumulation of soil total C, total N, and organic N under litterbags. The mycelia significantly stimulated the accumulation of the inorganic N (ammonium-N and nitrate-N) but the presence of fine roots weakened nitrate-N accumulation. The presence of living roots and associated mycelia strongly affected the process of root decomposition and matter release in the litter-soil system. The results of this study should strengthen the understanding of root-soil interactions.

Highlights

Litter decomposition is a major process within nutrient cycling and energy flows in terrestrial ecosystems
The mass loss of the fine roots of A. halodendron was as high as 41.7–45.3% at the initial stage of decomposition (33 days), which was higher than the previous study (Luo et al, 2016a)
The difference in mass loss between treatments in this study indicated that the presence of the mycelia significantly promoted the decomposition of the fine roots of A. halodendron

Summary

Introduction

Litter decomposition is a major process within nutrient cycling and energy flows in terrestrial ecosystems. Fine root turnover is an important source of soil carbon (C) and nitrogen (N) during the development of plant roots (Jackson et al, 1997; Silver and Miya, 2001). The carbon contribution of fine roots to terrestrial ecosystems is of great importance because of their rapid turnover despite the relatively small proportion of fine roots (Silver and Miya, 2001; Stover et al, 2010; Finér et al, 2011; Huang et al, 2012; Sariyildiz, 2015). Root decomposition is the main and stable source for the accumulation of soil matter such as organic C and nutrient elements (Luo et al, 2016a; Liebmann et al, 2020)

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Discussion

Conclusion