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Wageningen University (2012)

Ash unraveled : a descriptive study about physical, chemical and spectral characteristics of ash and soil in a Mediterranean forest after a large wildfire Mount Carmel area, Israel

Vincentie, H.

Titre : Ash unraveled : a descriptive study about physical, chemical and spectral characteristics of ash and soil in a Mediterranean forest after a large wildfire Mount Carmel area, Israel

Auteur : Vincentie, H.

Université de soutenance : Wageningen University

Grade : Master of Science (MS) 2012

Résumé
The presence of wildfires is a growing issue in Mediterranean areas. Defining a standardized method of assessing fire impact on soils is a challenging task due to high environmental heterogeneity. In this study an attempt is made to take up that challenge and see whether it is possible to combine traditional field and lab methods with modern hyperspectral analysis in the Carmel mountains, Israel (5 months after a large wildfire) in order to develop a tool with which wildfire effects on soil can be examined quickly. In recent literature, a number of soil parameters are described as major soil characteristics that are influenced by wildfires. Soil moisture, water repellency, organic matter content and aggregate stability are a few of these parameters. The different top soils in a severely burnt area show that there is a relation between ash type and water repellency. White ash contains a relatively high percentage of silt and is either highly wettable (top soil) or strongly water repellent (subsurface soil). Black ash contains a high amount of organic matter (as expected because of the dark color) and bare soil is the least water repellent of the three. PLSR (partial least square regression) examines the ability to predict each of these soil characteristics with spectral signatures. This seems possible for water repellency and soil organic matter content. Spectral analyses are surprising as this study shows that white is not always white. White ash gives significantly lower spectral signatures in both the visible ( 400-700µm) and the total spectrum (350-2500µm).

Mots clés : wildfires / soil chemical properties / soil physical properties / soil properties / ash / spectral analysis / organic matter / soil water / land degradation / israel / mediterranean region

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Page publiée le 26 janvier 2015, mise à jour le 19 octobre 2018