Decision scenarios using ecosystem services for land allocation optimization across Gharehsoo watershed in northern Iran

The primary objective of this study was to use ecosystem services in land allocation across Gharehsoo watershed in Golestan Province, north of Iran. Hence, land suitability was assessed using multi-criteria evaluation (MCE) methods to develop forestry, agriculture, range management, construction, and conservation land uses. Ecosystem services including water yield, habitat quality, and aesthetic quality were also quantified using integrated valuation of environmental services and tradeoffs (InVEST) and MCE methods. Next, the land allocation was investigated under five scenarios developed based on the land suitability and ecosystem services, namely land suitability, water yield, habitat quality, aesthetic quality and integration scenarios. The scenarios were then implemented using particle swarm optimization algorithm and compared to each other, based on the spatial land use variability and land use fragmentation. The results revealed that there is an obvious difference between the northern and southern parts of the region in terms of their land suitability and ecosystem services. An almost increasing trend was also observed for the allocated area to forestry, range management, and conservation land uses in the following order of scenarios: land suitability, aesthetic quality, water yield, integration, and habitat quality. However, an almost decreasing trend was obtained for agriculture and construction land uses in the same order of scenarios. Besides, range management and agriculture land uses had the highest and lowest spatial variability in all the scenarios, respectively. The results also clarified that the land use fragmentation decreased more in the water yield scenario than the other scenarios. This study indicated that using ecosystem services in land allocation can improve land use pattern and arrangement, consequently, helping take into account the ecosystem conditions in land use planning. In conclusion, this approach can help land managers to make appropriate decisions for maintaining ecosystem services in any region.