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TRENDS IN RECOVERY OF MEDITERRANEAN SOIL CHEMICAL PROPERTIES AND MICROBIAL ACTIVITIES AFTER INFREQUENT AND FREQUENT WILDFIRES

Authors

  • R. Guénon,

    1. Institut Méditerranéen d'Ecologie et de Paléoécologie, UMR CNRS 6116 IRD 193, Equipe Ecologie Microbienne et Biotechnologie, Service 452, Faculté des Sciences et Techniques de Saint-Jérôme, Université Paul Cézanne Aix-Marseille 3, 13397 Marseille cedex 20, France
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  • M. Vennetier,

    1. Cemagref, 3275 route de Cézanne, CS 40061, 13182 Aix en Provence cedex 5, France
    2. Fédération de Recherche ECCOREV (FR 3098), Europôle Méditerranéen de l'Arbois, Bâtiment du CEREGE BP 80, 13545 Aix en Provence cedex 4, France
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  • N. Dupuy,

    1. Institut des Sciences Moléculaires de Marseille, UMR CNRS 6263, équipe AD2EM, groupe systèmes chimiques complexes, service 451, Université Paul Cézanne Aix-Marseille, Faculté des Sciences et Techniques de Saint-Jérôme 13397 Marseille cedex 20, France
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  • S. Roussos,

    1. Institut Méditerranéen d'Ecologie et de Paléoécologie, UMR CNRS 6116 IRD 193, Equipe Ecologie Microbienne et Biotechnologie, Service 452, Faculté des Sciences et Techniques de Saint-Jérôme, Université Paul Cézanne Aix-Marseille 3, 13397 Marseille cedex 20, France
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  • A. Pailler,

    1. Institut Méditerranéen d'Ecologie et de Paléoécologie, UMR CNRS 6116 IRD 193, Equipe Ecologie Microbienne et Biotechnologie, Service 452, Faculté des Sciences et Techniques de Saint-Jérôme, Université Paul Cézanne Aix-Marseille 3, 13397 Marseille cedex 20, France
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  • R. Gros

    Corresponding author
    1. Institut Méditerranéen d'Ecologie et de Paléoécologie, UMR CNRS 6116 IRD 193, Equipe Ecologie Microbienne et Biotechnologie, Service 452, Faculté des Sciences et Techniques de Saint-Jérôme, Université Paul Cézanne Aix-Marseille 3, 13397 Marseille cedex 20, France
    2. Fédération de Recherche ECCOREV (FR 3098), Europôle Méditerranéen de l'Arbois, Bâtiment du CEREGE BP 80, 13545 Aix en Provence cedex 4, France
    • Institut Méditerranéen d'Ecologie et de Paléoécologie, UMR CNRS 6116 IRD 193, Equipe Ecologie Microbienne et Biotechnologie, Service 452, Faculté des Sciences et Techniques de Saint-Jérôme, Université Paul Cézanne Aix-Marseille 3, 13397 Marseille cedex 20, France.
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ABSTRACT

Since the 1970s, increase in fire frequency has been observed in all European Mediterranean regions. The objectives of this study were (1) to determine the effects of wildfire frequency on the recovery at short- and long-term of soil chemical and microbial properties and (2) to identify the mechanisms underlying the recovery of these sites properties. Soils from 17 plots (Maures mountains range, Var, France) were classified into 5 wildfire regimes (i.e. not burned since at least 57 years ago, infrequently and frequently burned-with time since fire between 4 and 17 years). Soil samples from these plots were analysed for their nutrient content, chemical functions of soil organic matter (SOM) using FT-MIR spectroscopy and microbial mineralising activities. Our results showed that the frequent wildfire regime slowed down the recovery in the short term of SOM spectroscopic properties and nutrient availability. Both low quantity and low quality (i.e. high percentage of aromatic and phenolic organic forms) of soil organic matter were found to be related to soil microbial recovery at 4 years after frequent wildfires. The frequent wildfires improved the recovery in net nitrification and nitrate content, leading to an increase in catabolic evenness and a recovery in microbial C-substrate utilisation profiles between 4 and 17 years. However, frequent wildfires slowed down the recovery of hydrolytic enzyme pool (i.e. FDA hydrolases) and phenol oxidase activity, both involved in soil C cycling. Overall, our observations suggest that 4 fires in 50 years is a threshold beyond which soil quality may be endangered. Copyright © 2011 John Wiley & Sons, Ltd.

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