Experimental prescribed burning in Turkey oak forest of Cilento and Vallo di Diano National Park (Southern Italy): effects on vegetation and soil

Abstract

An experimental prescribed burn was conducted in February 2011 in a Quercus cerris forest in the Cilento e Vallo di Diano National Park (Southern Italy) to analyze fire effects on vegetation and soil. Fuel fire behavior characteristics and were assessed to define the burning conditions that allowed a rate of fire spread between 0.10 and 0.22 m min-1, fireline intensity never below 50 kW m-1 and maximum flame temperatures in the litter of 600°C but the average residence time above 60°C and 300°C were 198 and 12 seconds, respectively. Litter fuel consumption ranged between 80% and 90%. The effect of fire on vegetation was evaluated in terms of floristic composition and structure by means of phytosociological and dendrometric samplings randomly located in burned and unburned plots two years after fire. The effect of fire on soil was evaluated by determining soil chemical (pH, water content, total and extractable organic C content, total and mineral N) and microbial properties (microbial biomass, soil potential respiration) in the 0-5 cm soil at different time since fire (3 hours, 30, 94, 209 and 394 days). Moreover, water holding capacity and bulk density were measured in burned and unburned plots at first sampling. Results on vegetation evidenced no significant differences in species richness and diversity, in both burned and unburned plots. No changes have been found in frequency and cover values of endemic species (Digitalis micrantha, Echinops ritro subsp. siculus, Lathyrus jordanii, Teucrium siculum). Woody species showed a great resilience with very low tree mortality. Sapling persistence by high sprouting rootstocks evidenced no significant difference in the abundance of some species (Quercus cerris, Acer campestre, Carpinus betulus, Crataegus monogyna) or an increase for few species (Ruscus aculeatus, Ilex aquifolium, Erica arborea, Fraxinus ornus, Sorbus torminalis, Carpinus orientalis) in burned plots. Results on soil showed that prescribed burning did not affect soil chemical and microbial properties, so indirect effects on plants deriving on effect of fire on soil may be excluded. Our findings highlight the sustainability of prescribed burning in Quercus cerris forests and support its future use as a management tool of fire risk reduction without significant impact on vegetation and soil.