Extended Abstract
Introduction: Forests and rangelands are considered among the richest sources of ecosystem services. With population growth and the intensification of natural resource exploitation, the demand for these services has increased dramatically. Understanding these services and the extent of human dependence on them highlights the need for the development of systematic frameworks for their economic valuation. Among these ecosystems, the Zagros rangelands stand out as one of the most critical ecological systems in Iran, currently facing escalating threats. Although these rangelands play an irreplaceable role in regulating water and soil cycles, conserving biodiversity, and supporting the livelihoods of local communities, increasing pressures from overexploitation and unsustainable management have placed their survival at serious risk. The objective of this study was to conduct an economic valuation of the most important ecosystem services provided by the rangelands in the Kolashak watershed.
Materials and Methods: In this study, the Kolashak watershed, encompassing an area of 9,110.2 hectares and located in Gilan-e Gharb County, Kermanshah Province, was investigated. First, all essential base maps, including topography, vegetation cover, land use, and soil maps, were prepared and processed within a GIS environment. Subsequently, the most important ecosystem services were assessed, comprising regulatory services (functions: carbon sequestration and oxygen production)****, supporting services (functions: soil formation and nutrient conservation)****, and provisioning services (function: forage production). The economic valuation of these services was conducted using the replacement cost method. Finally, the total economic value of ecosystem services in rangeland land use was estimated.
Results and Discussion: The economic value of each hectare of rangeland in the study area was estimated at 784,247 Thousand Rials per hectare per year. Among the assessed services, oxygen production (503,795 Thousand Rials) and carbon sequestration (248,976 Thousand Rials) contributed the most to this economic value. The average carbon sequestration in the rangelands was estimated at 24.96 tons per hectare; 87% of which (21.74 tons) is stored in the soil, highlighting the role of rangeland soils as key carbon sinks. Regarding oxygen production, calculations based on photosynthesis equations indicated that each hectare of rangeland annually produces an average of 3.7 tons of oxygen (equivalent to 11,077.8 tons across the entire watershed), sufficient to meet the annual oxygen needs of 12 individuals. These findings suggest that rangelands with greater vegetative cover and larger areas have a higher capacity for carbon sequestration and oxygen production. Furthermore, the economic value of forage production was calculated at 29,540 Thousand Rials per hectare. The rangelands of the Kolashak watershed also play a vital role in soil conservation and erosion prevention. With an average erosion rate of 13.85 tons per hectare, these rangelands perform better than the region’s agricultural lands (17.43 tons per hectare). The rangelands prevent the annual loss of approximately 3,580 kg of soil per hectare, equating to an economic value of 1,815 Thousand Rials per hectare for nutrient retention. Additionally, the economic value of soil formation was estimated at 121,633 Thousand Rials per hectare. Although this value appears lower than that of other functions, it reflects the long time required for soil formation and the replacement cost-based valuation method. Overall, these results underscore the substantial ecological and economic importance of rangelands in maintaining biogeochemical cycles and moderating climate change.
Conclusion: Valuing environmental resources such as rangelands has two important applications. First, it is used in cost-benefit analysis to attract economic support for rangeland protection and to determine the amount of damage caused by rangeland degradation. Second, the estimated economic values can be used in generating the gross income of a sector of the economy. The findings highlight the significant economic value of ecosystem services provided by the rangelands in the Kolashak watershed. This valuable ecosystem is under increasing threat from factors such as overgrazing, land-use change, water erosion, and shifts in precipitation patterns. These threats emphasize the urgent need for sustainable management. The results of this study can serve as a scientific foundation for management decisions and conservation planning, particularly in balancing livestock numbers with rangeland carrying capacity and improving grazing practices. Such measures can help simultaneously address the livelihood needs of local communities while ensuring the long-term health and functionality of rangeland ecosystems.