Effetti degli incendi in suoli su substrati calcarei in area Mediterranea

This study investigated fire effects on soils evolved on calcareous substrates. Two areas in south-central Sardinia (Laconi, burned in 2013 and S. Antioco in 2010) were chosen considering specific features. A grid sampling with regular spacing (100x100 m) was conducted on the two areas, identifying 40 soil sampling points in the burned (B) and 40 in the unburned areas (UB). Analysis of bulk density, soil texture, electrical conductivity, pH, organic matter, nitrogen, phosphorus and hydrophobicity were conducted on the 160 soil samples. Surface rate of spread, fireline intensity and flame length, evaluated by BehavePlus 5.0.5, were the parameters of the investigated fires. The differences between the physical-chemical soil properties of the B and the UB area were identified by variance analysis (ANOVA). The multiple correlations were evaluated by Principal Factor Analysis (PFA). The results show that, in both areas, fires were characterized by high severity. This affected some physical-chemical properties of the soils, though these differences are often not generalizable but rather site-specific. In general, high severity fires seem to have played a key role, since in both sites the PFA extracts most of the parameters related to fires. Fires may have exerted a marked influence on surface hydrological processes and this influence may have been amplified by strong gradient conditions able to increase the severity of the fire and, consequently, of the underlying erosive processes.