At What Depth Are The Properties of a Gypseous Forest Topsoil Affected By Burning?

Abstract

Wildfires represent one of the main factors of land degradation in Mediterranean environments having negative effects to several ecosystem services. In this work, the fire‐induced changes associated with depth (O horizon and Ah at 0–1, 1–2 and 2–3 cm depths) were studied in a gypseous soil under Aleppo pine forest. Topsoil monoliths were burned in an outdoor combustion tunnel simulating a fire of moderate intensity. In the O horizon, burning caused an immediate and significant decrease in water repellency (WR), total organic carbon (TOC) and pyrolyzed carbon (PyC) and an increase in total inorganic carbon. The Ah horizon was also significantly affected by fire, but mainly in its first shallower centimetre and with a different direction according to soil properties: TOC, gypsum, WR and PyC decreased, whereas soil aggregate stability and pH increased. Soil burning not only involved the loss of the pre‐fire organic matter content of the O horizon and the upper centimetre of the Ah horizon but also decreased their relative abundance of markers of resins, lignin and polysaccharides. Moreover, the soil burning exerted the cracking of alkylic long‐chain molecular series, some of them until the 2 cm Ah depth. The reduction of organic lipophilic molecules in the upper soil centimetre may be related to the fire‐induced decreases in WR. Moderate burning of the studied gypseous ochric horizon does not modify any of the properties studied at depths greater than 2 cm. Copyright © 2013 John Wiley & Sons, Ltd.

Effect of prescribed fire on soil properties and soil erosion in a Mediterranean mountain area

“…The direct and indirect effects of fire were often studied in soil surface (e.g., Arocena and Opio, 2003;Huseyin, 2006;Thomaz and Fachin, 2014;Meira-Castro et al, 2015;Armas-Herrera et al, 2016;Aznar et al, 2016), but some works showed that these effects reach deeper soil layers, at least down to 30 cm (Fonseca et al, 2011;Dennis et al, 2013;Heydari et al, 2017). The present work is in agreement with the results presented by the former authors, contributing to reinforce the idea that more attention should be given to the direct and indirect effects of fire at deeper depths.…”

Soil microbiological properties and enzymatic activities of long-term post-fire recovery in dry and semiarid Aleppo pine (<i>Pinus halepensis</i> M.) forest stands

“…Fire may alter physicochemical soil properties (i.e., soil organic matter content and structure, hydrophobicity, pH and nutrient cycles) and microbiological or biochemical soil properties (i.e., microbial biomass, microbial activity, soil enzymes activities) (Mataix-Solera et al, 2009). These changes mostly occur below 5 cm of the surface, where the soil temperature rarely overtakes 100 • C (Úbeda and Outeiro, 2009;Aznar et al, 2013). Post-fire silvicultural treatments may also modify the soil microbiological and biochemical variables, such as belowground biological activity and soil nutrients' availability (Grady and Hart, 2006) or enzyme activities (Wic-Baena et al, 2013).…”

Molecular characterization of wildfire impacts on organic matter in eroded sediments and topsoil in Mediterranean eucalypt stands

“…The effects of fire on SOM quality continue an important research gap, also because recent advances and, in particular, the use of pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), also called analytical pyrolysis, have shown that these effects can be very complex (Aznar et al, 2013;Badía-Villas et al, 2014a;De la Rosa et al, 2008bGonzález-Pérez et al, 2004). Analytical pyrolysis provides information concerning the structure of organic molecules, including N species, which cannot be released by hydrolysis.…”