Nitrogen and phosphorus cycling following prescribed burning in natural and managed Aleppo pine forests

Two prescribed burnings (downhill and uphill fires) were conducted in two stands of Aleppo pine (Pinus halepensis Mill.): a natural stand and a managed stand that was subject to thinning, pruning, and shrub removal. The concentrations of nitrogen (N) and phosphorus (P) in the pine needles and regrowth of the main shrub species, Quercus coccifera L., and the quantities of N and P in the needle fall and in the forest floor were measured during the 6 months following the fires. The concentrations of N and P in the pine needles and leaves of Q. coccifera increased compared with the unburned control after both fires in the natural stand, where there was only a slight reduction in fuel during prescribed burnings and where there was an abundant fall of scorched needles. In contrast, the chemical composition of the foliage was unchanged after the fires in the managed stand, where there was a greater reduction in fuel, and where only small quantities of scorched needles fell. This study showed that first opening prescribed burnings (natural stand) were less severe in terms of nutrient balance than maintenance prescribed burnings (managed stand) and that the forest floor reduction was a good indicator of fire severity.