Post-fire erosion control: monitoring the effects of soil bioengineering techniques

Forest fires significantly increase susceptibility to soil erosion, primarily due to the loss of vegetation cover and alterations in soil hydrophysical properties, including reduced infiltration capacity and increased surface runoff. The processes that occur can have significant economic, ecological and socio-cultural impacts. Mediterranean environments are particularly susceptible to erosion due to the combination of climatic, pedological, and geomorphological factors, including rainfall patterns, soil physical and structural characteristics, land use, topography, and fire occurrence. Furthermore, the climate change scenarios currently in place are set to accentuate erosion rates in areas affected by fires. In this context, soil bioengineering interventions represent effective low environmental impact mitigation strategies for the reduction of post-fire erosive processes.

The study aims to understand the effects of post-fire through the application of targeted intervention strategies such as soil bioengineering techniques. This study allows to explore deeper into the effects of carrying out a pilot soil bioengineering intervention within the 1900-hectare wooded area “Bosco Difesa Grande” located in Gravina in Puglia (Bari, Italy), where a fire of 1170 hectares was recorded on 12/08/2017, and to analyze the restoration of the soil development capacity of some selected species. Between 2022 and 2023, interventions were carried out in two equally sized areas located along slopes with the same general conditions (slope, soil type, fire severity), except for exposure. Various works were carried out, such as the construction of a trellis, the removal of weeds, the construction of palisades and wattles, and the planting of native shrubs and tree species.

A monitoring plan was planned, through field activities during which counts of surviving live plants were carried out, and using satellite imagery to assess the average NDVI of the area, to understand the effects of the soil bioengineering interventions carried out. Two years later, the two areas have recorded different results: in area 1, the survival rate has reached approximately 87%, while in area 2, spontaneous plants have a very intense development that prevents the correct development of project plants. Regarding NDVI values, a mean increase was detected in both areas.