Efficiency and Impact of Prescribed Burning in Pinus laricio Forest ^†

Like many Mediterranean regions, Corsica is frequently exposed to forest fire risk. The development of preventive techniques is therefore essential to preserve these ecosystems. Prescribed burns allow the reduction in surface fuels and are often combined with other forest-management methods such as pruning or grinding. Nevertheless, little is known about the impact of prescribed burning on the soil of Pinus laricio forests.

In order to provide new insights, prescribed fires were conducted by forest managers in autumn 2020 in both thinned and untreated plots. The study site was located in a Pinus nigra subsp. laricio pine forest in the Bavella massif (1200 m altitude, Corsica, France). Temperature measurements were performed at the surface and at different depths in the soil using thermocouples. A GIS representation of the different fuel (grass, litter, and thinning residues) was realized before and after burning. Concurrently, a monitoring of the physicochemical parameters of the soil and the recolonization of the environment by organisms (arthropods, bacteria, fungi, etc.) was carried out.

The results show significant increase in the temperature at the soil surface (near 1000 °C) during fire spread. Conversely, low in-depth temperature variations (+13 °C max at 3 cm deep) were observed, resulting in low fire impact within the soil. Most of the litter, herbaceous stratum, and particles smaller than 6 mm in diameter (post-thinning residues and shrubs) were heterogeneously removed from the plots, creating a mosaic of environments for soil organisms. Post-burning sampling (24 November 2020) exhibit the presence of surviving organisms on the burned plots, which could allow for rapid recolonization of the environment. Post-fire monitoring (arthropods, soil litter) is also conducted up to 1.5 years after burning.