Estimation of the Economic Value of Soil Nutrition Protection in Zagros Forest Ecosystems (Case Study: Noujian Watershed in Khoramabad)

Soil is one of the most important natural resources of any country for which there is no alternative. One of the most important services and functions of forest ecosystem is to prevent soil erosion and increase nutrient retention capacity, which is especially important in steep and mountainous areas. In this research, one of the most important functions and services of the Noujian forests in Lorestan province, conservation and maintenance function of soil nutrition has been evaluated.

For this purpose, the first current status of erosion and sedimentation in each sub-basin of study area were investigated using the MPSIAC improved model. The test lasted about one year. With the development of two scenarios for the conversion of natural forest (Current forest) with 30-50% canopy into uncovered land through by rating the model, the changes in erosion and sedimentation have been estimated. Then, the soil nutrient content of the natural forest was determined by soil sampling and laboratory analysis. After that, considering the difference in the amount of erosion in the two condition and the amount of each nutrient component in soil, the amount of nutrient wasted was calculated. Then using the replacement cost method, the value of the function of maintenance of soil nutrients in forest ecosystem was estimated.

The results show that each hectare of forest in the study area can hold 0.09 kg of phosphorus, 2.60 kg of potassium and 37.89 kg nitrogen per year, at an approximate value of 328.47 thousand Rials/ha/year and prevent their loss due to soil erosion.

Estimating value of the ecosystem service in Zagros forests represents the very effective role of these forest ecosystems in controlling erosion and soil nutrient conservation. The obvious difference between the rate of erosion in the natural state and each of the deforestation cases indicates the key role of the forest in controlling soil erosion. In addition, the obvious difference between the estimates related to different sub-basins indicates the effective relationship between the structure and performance of the ecosystem. Evaluating ecosystem services can provide information that is more accurate to managers and planners in order to protect natural resources and lead to more detailed plans in this area.