Effects of inorganic nitrogen and litters of Masson Pine on soil organic carbon decomposition.

Xin Yu,Qingpeng Yang,Silong Wang,Guangjie Zhang,Lin Chao,Longchi Chen ,Wei‐Dong Zhang

doi:10.1371/journal.pone.0222973

Abstract

Soil organic matter (SOM) mineralization represents one of the largest fluxes in the global carbon cycle. Numerous studies have shown that soil organic carbon decomposition was largely changed owing to the addition of litter, however very few studies have focused on the role of plant organs in the priming effects (PEs). Here, we studied the effects of different Pinus massoniana organs (fresh leaf, leaf litter, twigs, absorptive fine roots, and transport fine roots) on C4 soil respiration by applying the 13C isotopic natural abundance method. Results showed that the effects of plant organs on PEs were significantly different at the end of 210 days incubation, which can be ascribed to contrasting organs traits especially non-structural carbohydrates and water-soluble compounds. Transport fine roots and fresh leaf induced positive PE, whereas absorptive fine roots induced negative PE. Leaf litter did not change the native SOC decomposition. Plant organ addition can change the microbial community and result in the reduction of bacteria-to-fungi ratio. Our results suggest that with regard to determining the PE of the entire ecosystem, using fresh leaf to represent leaf litter and aboveground to represent underground is implausible.

Highlights

Soil organic matter (SOM) mineralization represents one of the largest fluxes in the global carbon (C) cycle [1]
Repeated-measures ANOVA and k showed the CO2-C derived from plant organs was significantly affected by litter components (P < 0.001) (Fig 2 and Table 2)
N and litter components significantly affected the amount of organ-derived CO2-C (P = 0.017 and P < 0.001, respectively)

Summary

Introduction

Soil organic matter (SOM) mineralization represents one of the largest fluxes in the global carbon (C) cycle [1]. Forest SOMs are the biggest C pool in the terrestrial ecosystem; a litter change in these SOMs will vastly affect the global C balance [2]. Understanding the factors that regulate SOM turnover is essential to predict the terrestrial feedback on climate change [3]. Fresh organic matter can form new soil organic carbon (SOC) during litter decomposition [4]. Fresh organic substrates can stimulate the decomposition of stabilized SOC through a phenomenon called the priming effect (PE) [5]. Plant litter typically comprises different organs, such as leaf litter, twigs, fine roots, and others (e.g., reproductive organs, bark, and detritus).

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Conclusion