Impact on soil and tree community of a threatened subtropical phytophysiognomy after a forest fire

Knowledge about the effects of fire on tree communities of Araucaria forests (AF) is scarce, although this physiognomy is among the most threatened ones in the entire Brazilian hotspot Atlantic Forest. With this study, we sought to answer the following questions: After three years of the fire, how has the soil of this forest remnant been recovering? Are fires in the AF able to change the structure, composition and species richness of tree community? The survey was carried out in a remnant of AF in an integral protected area in Brazil. Two areas were selected, one that has no fire history in the last 30 years (unburned) and another that burned recently. In each area 25 permanent plots of 20 × 10 m were allocated and all shrub-tree vegetation with DBH ≥ 4.8 cm was sampled. Our initial expectations were largely refuted, since we found no differences between the two areas in composition and richness of tree species and in most soil environmental variables, but only in the community structure. The majority of the dead individuals were concentrated in the smallest diameter classes (DBH < 9.8 cm). The only soil environmental variables that presented differences were pH and organic matter. Our study shows that the AF presents a significant resistance against forest fires, probably due to the evolutionary history of this physiognomy with fire. Nevertheless, several individuals died, so it is also important to highlight that preventive measures against fires are always relevant for conservation of this endangered physiognomy.