13C NMR spectroscopy characterization of particle-size fractionated soil organic carbon in subalpine forest and grassland ecosystems

Yo-Jin Shiau,Guanglong Tian,Tay-Lung Chung,Chih-Yu Chiu,Jenn-Shing Chen

doi:10.1186/s40529-017-0179-5

Yo-Jin Shiau, Guanglong Tian + Show 3 more

Open Access

https://doi.org/10.1186/s40529-017-0179-5

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Journal: Botanical Studies	Publication Date: May 30, 2017
Citations: 11	License type: open-access

Affiliation: Biodiversity Research Center, Academia Sinica

Abstract

BackgroundSoil organic carbon (SOC) and carbon (C) functional groups in different particle-size fractions are important indicators of microbial activity and soil decomposition stages under wildfire disturbances. This research investigated a natural Tsuga forest and a nearby fire-induced grassland along a sampling transect in Central Taiwan with the aim to better understand the effect of forest wildfires on the change of SOC in different soil particle scales. Soil samples were separated into six particle sizes and SOC was characterized by solid-state 13C nuclear magnetic resonance spectroscopy in each fraction.ResultsThe SOC content was higher in forest than grassland soil in the particle-size fraction samples. The O-alkyl-C content (carbohydrate-derived structures) was higher in the grassland than the forest soils, but the alkyl-C content (recalcitrant substances) was higher in forest than grassland soils, for a higher humification degree (alkyl-C/O-alkyl-C ratio) in forest soils for all the soil particle-size fractions.ConclusionsHigh humification degree was found in forest soils. The similar aromaticity between forest and grassland soils might be attributed to the fire-induced aromatic-C content in the grassland that offsets the original difference between the forest and grassland. High alkyl-C content and humification degree and low C/N ratios in the fine particle-size fractions implied that undecomposed recalcitrant substances tended to accumulate in the fine fractions of soils.

Highlights

Soil organic carbon (SOC) and carbon (C) functional groups in different particle-size fractions are important indicators of microbial activity and soil decomposition stages under wildfire disturbances
total organic carbon (TOC) and total nitrogen (TN) content in different particle-size fractions was seemingly increased with decreased particle sizes, but was masked statistically (P = 0.62 and 0.15, respectively) (Table 3)
TOC content was higher in forest than in the grassland and transition zone (P < 0.001), with no difference in C/N ratio or TN among the three locations

Summary

Introduction

Soil organic carbon (SOC) and carbon (C) functional groups in different particle-size fractions are important indicators of microbial activity and soil decomposition stages under wildfire disturbances. Soil organic carbon (SOC) is one of the most important indicators of soil quality (Reeves 1997) It improves soil physical properties such as holding soil water and reducing soil bulk density (Manns and Berg 2014) and helps in the development of the microbial community (Beyer 1995). The chemical composition of SOC in particle-size fractions may affect soil microbial activity and decomposition rate of SOC (Beyer 1995) This information can be valuable for determining changes in the SOC pools with changes in plant cover or climate (Rossi et al 2016). Wildfire decreases humic substance content and affects the aromaticity of humified fractions (Vergnoux et al 2011b)

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