Estimating the economic value of the preservation and maintenance functions of soil nutrients in Zagros forest ecosystem (case study: Dalab Ilam region)

In this research, one of the most important functions and services of the forest, the function of maintaining soil nutrients in the forests of the Dalab watershed in Ilam province, has been valued. First, the amount of erosion and sedimentation in the study area was checked using the modified MPSIAC model in the current condition. By developing two scenarios of converting the (current) natural forest with 30 to 50% canopy cover to bare land through scoring the model, the changes in the amount of erosion and sedimentation were estimated. Next, the amount of soil nutrients was determined by soil sampling and laboratory analysis. Then, taking into account the difference in the amount of erosion in the state of natural forest (current) with 30-50% canopy cover and bare land, the amount of each nutrient element in the soil, and the loss of soil nutrients was also calculated. Then, using the replacement cost method, the service value of forest ecosystem soil nutrient maintenance was estimated. The results showed that the studied forest can maintain 2.52 tons of phosphorus, 35.55 tons of potassium, and 251.96 tons of nitrogen per year with an approximate value of 2,275,700 million rials per year and prevent its loss due to erosion. Also, the value of each hectare of forest for this function was estimated at 88.13 million rials. The estimation of the value of this ecosystem service in Zagros forests indicates the very effective role of forest ecosystems in controlling erosion and protecting soil nutrients.