علوم مراتع
سال:1396 | دوره:7 | شماره:3 |تعداد مقالات:12

Evaluating rangelands means to identify and create potential and actual rangelands in order to utilize this valuable natural resource properly. Hence, one of the important factors in rangeland management is to determine range suitability and recognize factors affecting it. Weighted Linear Combination Method (WLC) is one of the most common methods used for locating and Analytic Hierarchy Process (AHP) method is one of the most used methods of criteria prioritization and weighting. The purpose of this study was to evaluate range suitability of Bagheran Birjand watershed area in Southern Khorasan Province, Iran using AHP-Fuzzy method in a region with an area of 11879 ha in 2014. For this propose, in the environment of Geographical Information System (GIS), the maps of factors affecting the suitability (slope, production, erosion, quality of water resources, water need estimation percent and distance from water sources) were prepared. Data were standardized using fuzzy method and for weighting the criteria, the Analytic Hierarchy Process method was used. The results of AHP-Fuzzy model based on the weighted linear combination showed that 55.43% of rangelands were in suitability class of moderate suitability (S2), 9.55% of the lands were in suitability class of low suitability (S3) and 6.21% of the lands were in non-suitability (N) class. So, the limiting factors in this model for sheep grazing in the study area are water resources, high slope and vegetation.

One of the most important issues in structure-function relationship modeling is that each rangeland has numerous functions and each of them can provide the most benefits in a certain state of that ecosystem. In fact, relationship between structure and function can be varied in different states. After presentation of the Linear Structure-Function Model based on the Clementsian succession theory, another conceptual model was proposed to modify it based on more realistic State and Transition theory. While previous models mostly suppose one single function in their simulations, in this article, we suggest a conceptual model that summarizes the relationships between Ecosystem Structure and Multiple Functions (ESMF) in various states. The model can be useful for rangeland managers to get a rather correct understanding about multiple functions in rangelands. By this right understanding, the rangeland managers will be able to identify the best states for their ecosystems and try to reach to these states which can provide totally maximum benefits. This model shows that some functions in rangelands may conflict with or overlapped each other and some functions may not show a meaningful relationship with structure in ecosystems so that it is a very important task for managers to choose the states with the highest benefits and less conflict.

Introduction: Scientists call pasture a natural ecosystem and range is an agricultural ecosystem.In this point of view although pasture that was full of plants growing by itself and not growing by human being (Pirdashti, 2007; Mohgadam, 2005) and two groups of living beings such as human being, plants, domesticated, and not living being like weather, Wind, gradient which are effective in making of pasture.....