FIRE-INDUCED TRANSFORMATION OF SOIL ORGANIC MATTER FROM AN OAK FOREST

Abstract

This study is about the effects of forest fire on the organic matter from a Dystric Xerochrept under Quercus rotundifolia. In laboratory experiments carried out to simulate the effects of fire on isolated humic fractions, several physicochemical characteristics were described in the heated samples, as well as in humic substances extracted from samples of control and postfire soil areas. The results obtained suggested that humic and fulvic acids underwent moderate structural modifications, but we found important changes in their colloidal properties, particularly regarding solubility. The composition and properties of pyromorphic humus are discussed by using a tentative model for humus transformation on the basis of different fire-induced modifications of the soil organic fractions.