Evaluation of changes in soil in the short and medium term due to a forest fire in the pine forest of Tenerife (Canary Islands, Spain)

Forest fires lead to important changes in soil properties, which sometimes are non-reversible. In the Canary Islands, fires burn mainly Canarian pine (Pinus canariensis) forests. This work evaluates the impact and evolution of some relevant physico-chemical and biological properties in burned soils affected in an area under Canarian pine forest in the NW of Tenerife. Four sites with different understory composition were selected, together with similar, unaffected neighboring areas as controls. In these areas, soil samples were gathered periodically (four times in each plot), along a period ranging between three months and three years after the fire. Samples were analyzed for different physico-chemical and biological parameters. The results showed increases in burned areas for pH, EC1: 5 and NH4+-N three months after the fire, without differences in further samplings. Increases were also found for the oxidizable carbon (Cox), total nitrogen (Ntot) available cations, and water repellency. Furthermore, a considerable increase in soil respiration in the area affected by the fire was observed in the first sampling. However, this zone is also characterized by an initial decrease in the microbial biomass-linked organic C, and some enzymatic activities, particularly the phosphomonoesterase. In time, the enzymatic activities studied recovered progressively, without reaching the values measured at unburned areas.