Chin J Plant Ecol ›› 2014, Vol. 38 ›› Issue (11): 1174-1183.DOI: 10.3724/SP.J.1258.2014.00113

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Effects of vegetation restoration on content and spectroscopic characteristics of dissolved organic matter in eroded red soil

LIU Zhu,YANG Yu-Sheng,SI You-Tao(),KANG Gen-Li,ZHENG Huai-Zhou   

  1. State Key Laboratory Breeding Base of Humid Subtropical Mountain Ecology, School of Geographic Sciences, Fujian Normal University, Fuzhou 350007, China
  • Received:2014-04-30 Accepted:2014-09-07 Online:2014-04-30 Published:2014-11-17
  • Contact: SI You-Tao

Abstract: Aims Dissolved organic matter (DOM) plays an important role in soil nutrient cycling. The chemical stability, capability of absorption on mineral soil surface and availability to microbes of DOM could be influenced by its composition and chemical structure. The objective of this study was to investigate the effects of vegetation restoration on content and spectroscopic characteristics of DOM in eroded red soil.Methods The study site is located in Changting, Fujian Province, in subtropical China. Soil samples in the depth of 0-60 cm from eroded red soil (ERS) and vegetation restoration (VR) sites were collected in July, 2013. Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) contents were determined and the spectroscopic characteristics of soil DOM were measured by means of ultraviolet (UV) absorbance, fluorescence (in emission and synchronous modes) and fourier-transform infrared (FTIR) spectroscopic techniques. Important findings The content of soil DOC in VR was significantly higher than in ERS. For soil layers from 0 to 60 cm at a 10 cm interval, content of DOC in VR was 5.6, 4.7, 4.6, 3.1, 2.4 and 2.2 times of that in ERS, respectively. The difference in DON content between VR and ERS varied inconsistently across soil layers. In all soil layers, the Special Ultraviolet-Visible Absorption (SUVA) of DOM from VR was significantly higher than that from ERS; HIXem (Humification Index, emission mode) of DOM from VR was slightly higher than that from ERS; while there was no apparent difference in HIXsyn (Humification Index, synchronous mode) of DOM between the two sites. In the synchronous fluorescence spectra of DOM, the main emission peaks arose from protein-like and aromatic-aliphatic fluorophores. FTIR spectra showed that there were more functional groups in DOM from VR, with higher absorption proportion of aromatic rings and carboxylates. The aromaticity and humification index of soil DOM decreased with increasing soil depth at both sites, which were positively related to total soil organic carbon and nitrogen. In conclusion, vegetation restoration significantly increased the content of soil DOC and the aromaticity index of DOM, and slightly increased the humification index of soil DOM, rendering soil DOM to be more complex and less susceptible to degradation in favor of soil fertility recovery.

Key words: dissolved organic carbon, dissolved organic nitrogen, red soil, spectroscopic characteristics, vegetation restoration