This study compares the long-term effects of a wildfire on basic topsoil properties – bulk density, particle-size distribution, pH, electrical conductivity, total C and N, inorganic C, cation exchangeable capacity, available N, P, Ca, Mg, and K – in the Zagros oak forest, Iran, with those induced by agricultural activity in a vineyard planted 30 years earlier in place of the forest. The soil, Calcaric Cambisols according to the World Reference Base, was studied in: i) the unburned forest, both inside (FI) and outside (FO) sprout clumps; ii) the burned forest, in areas subjected to high (BHI) or moderate (BMI) severity (both inside sprout clumps) and low (BLO) severity (outside sprout clumps); iii) the vineyard, both under the foliage of vines (VI) and outside it (VO). In VI, VO, BHI and BMI most soil properties were significantly different from those of the unburned forest. A Hierarchical Cluster Analysis grouped together BHI and BMI and separated their unburned counterparts with 72% and 47% dissimilarity, respectively. The VI and VO treatments in the vineyard were closely related each other but separated from their unburned counterparts in the unburned forest soil with 149% and 69% dissimilarity, respectively. Overall, thirty years of farming were more impacting on soil than a single fire, although severe; nevertheless, severe fire appears to have been much more impacting than every single yearly plowing.
