Prediction of the most suitable areas for forestry, pasture and agriculture land uses using the multi-criteria evaluation (MCE) method

Introduction
In recent decades, the change in most land uses, regardless of the capabilities and limitations of the environment, has led to many problems such as soil degradation and pollution of aquatic ecosystems. Therefore, this study has been conducted to investigate how to reduce the effects of possible future land use changes in the Gorganrood watershed by examining the potential of lands as a solution to protect natural resources. Land management and appropriate use of natural resources in the region and the country in accordance with environmental characteristics are the basic and important principles of sustainable development. One of the basic points in land use planning is to observe the suitability of existing land uses for future utilizations. The meaning of land suitability is to match the characteristics of the land according to the type of use and activities. If the characteristics of the land can meet the needs and requirements of its use, that land will be suitable for its use. Assessing and determining land suitability involves comparing the requirements of each land use type based on the specifications and quality of each land unit. The study of ecological potential determines the appropriate type of land use for a region that can be considered as a base for sound land management. Several studies have been conducted in the field of assessing the ecological potential of the lands using geographical information system and multi-criteria evaluation methods, While, no study has been done to evaluate the ecological potential of future uses, which is an innovation of the present study. Predicting and locating potential areas can provide useful managers and tools for sustainable land management. As a result, the ineffectiveness of the one-dimensional approach and the need for comprehensiveness in adopting the best decisions and management methods, the use of different expertise, and the presentation of different management options and scenarios are necessary to choose the best scenario for land use changes in the future.
 
Materials and methods
The primary step in this study is to investigate how to reduce the effects of possible future land use changes in the Gorganrood watershed by examining the potential of lands as a solution to protect natural resources. Therefore, the Land Change Model (LCM) was used to investigate the possible changes in future land use, and then, using the Geographic Information System (GIS) and multi-criteria evaluation method (weighted linear composition), the most desirable areas for agricultural use, forests and pastures were determined. Land change modeling provides the possibility of analyzing changes to plan and experimentally model future land use changes and land cover. The main stages of land change modeling in order to model and land use changes are as follows: 1) preparation of land use maps; 2) Analysis and identification of changes in land use classes (analysis of changes);3) Modeling the transfer potential of land uses; 4) Predicting land cover changes; 5) Assessment of modeling accuracy (validation); 6) Modeling transmission potential and predicting future changes. Assessing the most suitable areas for future forestry, rangeland, and agricultural uses and preparing a map of the suitability of the area for these three uses using the multi-criteria evaluation method in several stages is described according to the following steps: 1) Goal setting and determining the effective criteria, 2) Standardization of criteria (factor and limitation); 3) Weighting of factors, 4) Integration using linear combination method.
 
Results and discussion
The results showed that during the study period (1990 to 2020), deforestation (279.53 km²), reduction of rangelands (542.598 km²), and agricultural development (413 km²) occurred in the Gorganrood watershed. According to the projected land use plan for 2040, the area of forest, agriculture, and rangeland will reach 1364.98, 2396.09, and 3481.1881 km² based on the current changes. Meanwhile, based on the ecological potential (Makhdoom model), the area of forest, agriculture, and rangeland will reach 1427.54, 2258.55, and 3567.549 km². According to the projected land use plan for 2040 under two management scenarios, the area of forest, agriculture, and rangeland in the first scenario (based on the current trend of change) by a change of -5.37, 35.8, and 8.28 km² to 1364.98, 2396.09, and 3481.18 km² will be reached. In this regard, reducing the area of forest lands and increasing the area of agricultural lands, rangelands and residential areas indicate that the human factor will play an important role in changing the land use of the Gorganrood watershed. Forest conservation such as afforestation, conservation of irrigated lands as well as rangelands, or limiting agricultural development in sloping lands or creating gardens in upstream rangelands and as a result sustainable watershed management should be adopted. Meanwhile, in the second scenario (based on ecological potential), the area of forest, agriculture, and rangeland changed by 4.27, -100.86, and 96.58 km² to 1427.54, 2258.55, and 3567.49 km² will be reached.
 
Conclusion
According to the results obtained during the study period, there was deforestation, loss of pastures, development of agricultural lands, and development of residential areas in the Gorganrood watershed. The assessment of land cover changes in the Gergunrood watershed showed that during the study period, the most changes were in forest cover and pasture destruction, and the largest increase was related to agricultural use, which was concentrated in the northeastern part of the watershed. The restoration arias with high priority should be determined according to changes in land cover use and in areas where changes in land cover change scenarios are predicted, preventive and protective measures should be taken considering the conditions of land use in the second scenario. Reducing the area of forest lands and increasing the area of agricultural lands, rangelands and residential areas indicate that the human factor will play an important role in changing the use of Gorganrood watershed lands. Preservation of irrigated lands as well as rangelands or limiting agricultural development in sloping lands or creating gardens in upstream rangelands and as a result sustainable watershed management should be adopted.