EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Molecular characterisation of soil organic matter under different burned vegetation canopies

Nicasio T. Jiménez-Morillo1, Ana Z. Miller2,3, Nuno Guiomar1,4, José M. De la Rosa3, Cristina Barrocas-Dias2, Ana Manhita2, and José A. González-Pérez3
Nicasio T. Jiménez-Morillo et al.
  • 1MED-University of Évora, Núcleo da Mitra, Ap. 94, 7006-554 Évora (Portugal).
  • 2HERCULES Laboratory-University of Évora, Palácio do Vimioso, 7000-809 Évora (Portugal).
  • 3IRNAS-CSIC, Avda. Reina Mercedes, 10, 41012, Seville (Spain).
  • 4EaRSLab, Earth Remote Sensing Laboratory, Colégio Luis António Verney, 7000-671 Évora (Portugal).

Forest fires are a recurrent ecological phenomenon in the Mediterranean basin. They induce molecular changes in soil organic matter (SOM) leading to immediate and long-term environmental consequences [1]. The SOM is of paramount importance as indicator of soil health [2]. Fire-induced changes in SOM include the alteration of biogenic chemical structures and the accumulation of newly formed ones, enhancing dynamics in the complex balance between the different C-types [2,3]. Therefore, understanding SOM molecular composition, before and after fire, is fundamental to monitor changes in soil health, as well as its natural or man-mediated recovery [3,4]. Our aim was to assess the molecular composition of organic matter in fire-affected leptosols, at two depths (0–2 and 2–5 cm) under different vegetation types located in the southwestern of Portugal (Aljezur, Algarve). The SOM characterization was conducted by analytical pyrolysis (Py-GC/MS), a technique based on the thermochemical breakdown of organic compounds in the absence of oxygen at elevated temperatures [5]. The Py-GC/MS has been found suitable for the structural characterization of complex organic matrices [4], providing detailed structural information of individual compounds considered fingerprinting of SOM. However, due to the relative high number of molecular compounds released by analytical pyrolysis, the use of graphical-statistical methods, such as van Krevelen diagrams, are usually applied to help monitoring SOM molecular changes produced by fire [3,4]. This work represents the first attempt to evaluate the fire effects in SOM using a detailed molecular characterisation of SOM under different vegetation canopies, recently affected by wildfire, in southern Portugal.



[1] Naveh, Z., 1990. Fire in the Mediterranean – a landscape ecological perspective. In: Goldammer, J.G., Jenkins, M.J. (Eds.), Fire in Ecosystems Dynamics: Mediterranean and Northern Perspective. SPB Academic Publishing, The Hague.

[2] González-Pérez, J.A., González-Vila, F.J., Almendros, G., Knicker, H., 2004. The effect of fire on soil organic matter—a review. Environ. Int. 30, 855–870.

[3] Jiménez-Morillo, N.T., De la Rosa, J.M., Waggoner, D., et al., 2016. Fire effects in the molecular structure of soil organic matter fractions under Quercus suber cover. Catena 145, 266–273.

[4] Jiménez-Morillo, N.T.; Almendros, G.; De la Rosa, J.M.; et al., 2020. Effect of a wildfire and of post-fire restoration actions in the organic matter structure in soil fractions. Sci. Total Environ. 728, 138715.

[5] Irwin, W.J., 1982. Analytical pyrolysis—a comprehensive guide. In: Cazes, J. (Ed.), Chromatographic Science Series, 22: Chapter 6. Marcel Dekker, New York.


Acknowledgments: This work was funded by national funds through FCT–Fundação para a Ciência e a Tecnologia (EROFIRE project, ref. PCIF-RPG-0079-2018). This research was funded by the European Union through the European Regional Development Funds in the framework of the Interreg V A Spain-Portugal program (POCTEP) through the CILIFO (Ref.: 0753_CILIFO_5_E) and FIREPOCTEP (Ref.: 0756_FIREPOCTEP_6_E) projects. In addition, this research was funded by the EU-FEDER co-funded project MARKFIRE (ref. P20_01073) from Junta de Andalucía. A.Z.M was supported by a CEECIND/01147/2017 contract from FCT, and a Ramón y Cajal contract (RYC2019-026885-I) from the Spanish Government (Ministerio de Ciencia en Innovación – MCIN).

How to cite: Jiménez-Morillo, N. T., Miller, A. Z., Guiomar, N., De la Rosa, J. M., Barrocas-Dias, C., Manhita, A., and González-Pérez, J. A.: Molecular characterisation of soil organic matter under different burned vegetation canopies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4571,, 2022.