BIOGEOCHEMICAL PARAMETERS SURROGATED TO THE RECOVERY OF SOILS AFTER FOREST FIRE EVENTS

Forest fires are considered as the main disturbance in the Mediterranean basin (Naveh, 1990) and exerts both immediate and lasting ecological and environmental impacts. This is in part caused by a depth transformation of soil physical, chemical and biological characteristics associated to qualitative and quantitative changes in the organic matter (OM) (González-Pérez et al., 2004) which is reflected in the structure of the whole system including microbial populations (Pastor and Post, 1986; Pietikäinen et al., 2000). This negatively affects soil health and quality favouring the occurrence of erosive processes and the lost of a non-renewable natural resource such is soil. However, the effects of fire on soil colloidal properties and on the microbial community are reversible. After the passage of fire soil properties may naturally revert to a situation close to that before fire; erodibility is reduced and soil functionality is again achieved (Cerdá, 2004). This is especially evident in the so-called cold fires including controlled burnings and fires in open forest at semiarid environments with pyrophytic vegetation (Mutch, 1970; Pyne, 1996). The starting hypothesis is that if reversible effects do occur, then we may be able to find out biogeochemical surrogated indicators informing on th