Temporal variations of runoff, erosion and soil nutrients affected by fires in oak forests of Lake Zaribar

Fires cause physical, chemical and biological changes in the soil such as porosity, specific gravity, infiltration rate, runoff, erosion, pH and nutrient cycling. The Eijkelkamp rainfall simulator and 0.09 m2 plots were used to investigate the temporal variations of runoff, erosion, suspended load concentration and the amount of total nitrogen, total phosphorus, and extractable soil potassium, and finally, how the burned areas in the Zarivar Lake Watershed returned to the previous conditions from 2014 to 2017 were analyzed. Results at the 95% confidence level showed a two-fold increase in the runoff in the short term, and a decreasing trend in the long term. The suspended load removed from the plots increased threefold in the short term. The fire also significantly increased total nitrogen, total phosphorus, and extractable potassium in the first year by 70, 286 and 48%, respectively. But in the long term, only the extractable potassium returned to the normal condition. Therefore, it was found that, after four years of fire in the oak forests of the Zaribar Lake Watershed, except for the suspended load concentration and extractable potassium, the other variables did not return to the normal conditions.