Decomposition of Leaves and Fine Roots in Three Subtropical Plantations in China Affected by Litter Substrate Quality and Soil Microbial Community

Da Luo,Ruimei Cheng,Zuomin Shi,Weixia Wang

doi:10.3390/f8110412

Abstract

Leaf and root litter decomposition has been a major research focus. However, the possible effects of belowground microbial community structure and diversity on this process are poorly understood. Understanding the biochemical mechanisms controlling aboveground decomposition processes is important to predict the changes of soil carbon and nutrient cycling in response to changes of forest management regimes. Here, we explore the biochemical controls of leaf and fine root decomposition in three subtropical plantations (Ford Erythrophleum (Erythrophleum fordii Oliver), Masson Pine (Pinus massoniana Lamb.)), and a mixed plantation containing both species) using the litterbag method, and soil microbial communities were determined using phospholipid fatty acid profiles. Overall, leaves decomposed more rapidly than fine roots, potentially due to the faster degradation of their cellulose component, but not lignin. In addition, leaf and fine root decomposition rates varied among plantations, being higher in E. fordii and lower in P. massoniana. Substrate quality such as N, Ca, lignin concentration, and C/N ratio were responsible for the decomposition rate changes among plantation types. Moreover, we used redundancy analysis to examine the relationships between litter decomposition and soil microbial community composition and diversity. Results revealed that actinobacteria and arbuscular mycorrhizal fungi community were the key determinants affecting leaf and fine root litter decomposition, respectively. Our work demonstrates that litter decomposition was linked to substrate quality and to the structure of soil microbial communities, and evidences the probable role of E. fordii in increasing soil nutrient availability, especially N, P and Ca. Additional data on phospholipid fatty acid (PLFA) or DNA marker groups within the litterbags over time may provide insights into litter decomposition dynamics, which represents potential objectives for future long-term decomposition studies.

Highlights

Litter decomposition is a crucial process influencing carbon (C) turnover and nutrient cycling in soils [1]
The ratios of C/N, C/P, and lignin/N, were significantly higher in the fine roots when compared to the leaves (p < 0.01 or p < 0.001), the N/P ratio was higher in leaves than in fine roots (p < 0.001). For both leaves and fine roots, Erythrophleum fordii showed the highest concentrations of N, Ca, cellulose, C/P and
We found that differences in the decomposition of cellulose, but not lignin, could be the main factor affecting decomposition of the two substrates

Summary

Introduction

Litter decomposition is a crucial process influencing carbon (C) turnover and nutrient cycling in soils [1]. Research on leaf litter decomposition has been carried out extensively in different forest ecosystems [3,4,5,6]. Understanding the mass loss dynamics and accompanying nutrient release patterns during root decomposition, and the factors that control these processes, are rather more limited when compared with leaf decomposition. In the few studies that compared decomposition processes of leaves and fine roots simultaneously, there appears to be no consistent trend in mass loss dynamics and nutrient release patterns [9,10]. To gain a comprehensive understanding of nutrient cycling in forest ecosystems, more studies comparing decomposition of leaves and fine roots are needed

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Results

Discussion

Conclusion