Evaluation of soil enzymes activities in an Araucaria–Nothofagus forest after a wildfire

Abstract

Catastrophic events in temperate forest ecosystems, such as wildfires, alter the dynamics of biogeochemical processes. Soil enzymes are critical to soil nutrient cycling function and their potential activities can be sensitive bioindicators of the temperate forest ecosystems resilience after wildfire events. In this context, this is a preliminary study, which has as main objective to evaluate the soil enzymes activities and their relationships with soil chemical parameters in Araucaria–Nothofagus forest after three years of the wildfire. Soil samples were collected from 0-20 and 20-40 cm depths, from two burnt plots (P1 and P2) and one non-burnt control plot (PC), three years after wildfire. We analyzed a composite soil sample from each plots (PC, P1 and P2) and each depth. The soil enzyme activities measured were catalase (CA), cellulase (CE) and urease (UR). Moreover, total nitrogen, total carbon, Olsen phosphorous, total phosphorous, sum of exchangeable bases and pH was measured. A multiple linear regression analysis was carried out in order to relate the soil enzymes activities and soil chemical properties. The results showed that the enzymes activities did not show any evident seasonality. On the other hand, the multiple lineal regression analysis demonstrated a weak association between the soil chemical parameters and the CA activity
(R² = 0.47) and CE activity (R² = 0.20), and a strong association with the UR activity (R² = 0.83). As a preliminary conclusion, soil UR activity could be a potential bioindicator of the alterations provoked by wildfire in Araucaria–Nothofagus forests, as three years post-wildfire there are still differences in its activity between burnt and non-burnt plots.