Wildfire effects on lipid composition and hydrophobicity in bulk soil and soil size fractions
Low soil-water affinity and soil water repellency (SWR, hydrophobicity) prevents water from wetting or infiltrating soils in burnt and unburnt ecosystems, causing various changes on their hydrology, geomorphology, geochemistry, and biochemistry. Wildfire may destroy, develop or enhance SWR in previously wettable or water-repellent soils (e.g., Doerr et al., 2009; Jordán et al., 2013 and references therein). SWR is at least in part attributed to a lipid-like cover, rich in fatty acids (FAs). Recently, it was shown that FAs had a major role in increasing the water repellency of unburnt sandy soils in Doñana National Park (DNP, SW-Spain), with Mediterranean climate and developed under trees (Quercus suber, Pinus pinea) and shrubs (Pteridium aquilinum, Halimium halimifolium) dominated vegetation (Jiménez-Morillo et al., 2016). To get further insight into how fire affect the distribution of soil lipids and their role in the SWR, a study was performed on different size fractions of a DNP sandy soil under Quercus suber canopy cover. Two soil samples were taken, one in a burnt site and another in an adjacent unburnt (control) one, both having the same physiographic characteristics. SWR was determined using water-drop-penetration-time test in the <2 mm sieved (bulk) soils and in six size fractions: 1-2 mm, 0.5-1 mm, 0.25-0.5 mm, 0.1-0.25 mm, 0.05-0.1 mm and <0.05 mm. Lipids were extracted from all samples (n = 14), and the FAs and neutral lipids were identified and quantified by GC/MS and GC/FID. The carbon isotope ratios (¿13C values) for the individual fatty acids were determined by GC/C/IRMS.
| Main Authors: | , , , , , |
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| Format: | comunicación de congreso biblioteca |
| Published: |
Université de Genève
2016-11-18
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| Online Access: | http://hdl.handle.net/10261/160464 |
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