Article
Effect of a Wildfire and of Post-fire Restoration Actions in the Organic Matter Structure in Soil Fractions
Author/s | Jiménez Morillo, Nicasio T.
Almendros, Gonzalo De la Rosa, José M. Jordán López, Antonio Martínez Zavala, Lorena María Pascual Granged, Arturo José |
Department | Universidad de Sevilla. Departamento de Cristalografía, Mineralogía y Química Agrícola |
Publication Date | 2020 |
Deposit Date | 2023-02-22 |
Published in |
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Abstract | The impact of wildfires and of restoration actions on soil organic matter (SOM) content and structure was studied in a soil under pine (Pinus pinea) from Doñana National Park (SW Spain). Samples were collected from burnt ... The impact of wildfires and of restoration actions on soil organic matter (SOM) content and structure was studied in a soil under pine (Pinus pinea) from Doñana National Park (SW Spain). Samples were collected from burnt areas before (B) and after post-fire restoration (BR) and compared with an unburnt (UB) site. Analytical pyrolysis (Py-GC/MS) was used to investigate SOM molecular composition in whole soil samples and in coarse (CF) and fine (FF) fractions. The results were interpreted using a van Krevelen graphical-statistical method. Highest total organic carbon (TOC) was found in UB soil and no differences were found between B and BR soils. The CF had the highest TOC values and FF presented differences among the three scenarios. Respect to SOM structure, the B soil was depleted in lignin and enriched in unspecific aromatics and polycyclic aromatic hydrocarbons, and in all scenarios, CF SOM consisted mainly of lignocellulose derived compounds and fatty acids. In general, FF SOM was found more altered than CF. High contribution of unspecific aromatic compounds and polycyclic aromatic hydrocarbons was observed in B-FF whereas BR-FF samples comprised considerable proportions of compounds from labile biomass, possibly due to soil mixing during rehabilitation actions. The fire caused a defunctionalisation of lignin-derived phenolics and the formation of pyrogenic compounds. The van Krevelen diagram was found useful to—at first sight—differentiate between chemical processes caused by fire and of the rehabilitation actions. Fire exerted SOM demethoxylation, dealkylation and dehydration. Our results indicate that soil management actions after the fire lead to an increase in aromaticity corresponding to the accumulation of lignin and polycyclic aromatic compounds. This suggests additional inputs from charred lignocellulosic biomass, including black carbon, that was incorporated into the soil during rehabilitation practices. |
Funding agencies | Ministerio de Economía y Competitividad (MINECO). España Fundação para a Ciência e a Tecnologia. Portugal Ministerio de Ciencia e Innovación (MICIN). España |
Project ID. | CGL2016-78937-R
CGL2013-43845-P CGL2013-47862-C2-1-R PCIF/RPG/0079/2018 BES-2013-062573 |
Citation | Jiménez Morillo, N.T., Almendros, G., De la Rosa, J.M., Jordán López, A., Martínez Zavala, L.M. y Pascual Granged, A.J. (2020). Effect of a Wildfire and of Post-fire Restoration Actions in the Organic Matter Structure in Soil Fractions. Science of the Total Environment, 728, 138715. https://doi.org/10.1016/j.scitotenv.2020.138715. |
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