The Soil Type As a Key Factor in the Ecosystem Response to a Forest Fire. Some Lessons Learned from Mediterranean Study Areas.

In the Mediterranean environment, forest fires are common and must be considered as an ecological factor, but changes in land use, and human activities, especially in the last five decades have provoked a modification in their natural regime. High severity fires are usual during the summer season affecting soil properties, but after decades of studies we can affirm that the soil type can control some of these changes even provoking different responses. In this contribution we want to summarize the main findings from different study sites in the Mediterranean basin, where we could check how the changes in some soil properties occurring after the fire were very dependent on the type of soil. In particular we will focus on 2 soil properties, aggregate stability and soil water repellency, that can show a very different response after fire depending on the soil type affected. We will show 3 different types of aggregate stability patterns of behaviour with fire intensity depending on the main binding agents involved in soil aggregation. In the case of soil water repellency, we observed that in most cases this property increases after fire, but we also observed that some soils like Òterra rossaÓ have very low susceptiblity to expressing water reppellency and after laboratory and field studies we conclude that clay content and mineralogy of clays are the main responsible factors for this behaviour. All this information must be useful for post-fire management strategies, avoiding doing some things that are not necessary, which in some cases could affect soil degradation more than the fire itself. Acknowledgements: to the ÒMinisterio de Econom’a and CompetitividadÓ of Spanish Government for finance the POSTFIRE project (CGL2013- 47862-C2-1-R), and Sierra de Mariola and Montg— Natural Parks por their collaboration