Document Type : Research Paper
Authors
1 MSc, Department of Natural Resources and Environmental Engineering, Shiraz University, Iran
2 Associate Professor, Department of Natural Resources and Environmental Engineering, Shiraz University, Iran
Abstract
Destroying natural resources and environment is one of the most important problems in different regions around the world, especially in arid zones. So that extent areas of these zones are being destroyed in extensive spectrum of these destruction processes. For this reason, evaluating and providing vulnerability map of vegetation degradation in our country can considerably help the management and executive planning. In the present research, the criteria used in a new model called NIDLTS are proposed for evaluating the vegetation degradation. These criteria are natural index(N), human indirect index (I), human direct index (D), livestock pressure (L), trend of degradation (T) and state indicators (S). In order to estimate each criterion, a number of risk index were used. Natural indices studied in this research were climate change, draught, climate and suitability of lands. Human indices which were studied are population density, population growth, governmental expenses from executive works and researches, changing natural resources land to agricultural lands, percentage of unemployment, percentage of illiteracy. The indices of studied status are percentage of crown cover, production of the present biomass and production of the present biomass to the potential. Hazard index related to each destruction group were classified in to five classes of hazard intensity with numerical values in order to be analyzed in GIS. Then, the weight of each index and each main group of NIDLTS framework were calculated by Hierarchy Analysis Process (AHP); so that giving priority was done through investigating their share and effects in the vegetation decline. Finally, the vulnerability map of vegetation risk was generated through overlaying all the layers for each criterion in GIS. Results showed that among the human factors, the changing land use from natural resources to agriculture is the most important factor, whereas among the natural factors, drought is the most important factor in the study area. Also, among all the criteria, natural index has the highest effect and the trend of degradation of natural resources lands has the lowest effect in the vegetation degradation during the time. The final hazard map showed that the most widespread hazard class is moderate, followed by no-hazard in the region. It seems logical that the proposed model of NIDLTS for assessing the hazard of vegetation degradation can provide a more accurate estimation of vegetation degradation in a region with taking into consideration of the ecological, anthropogenic and hazard trend in comparison with some other evaluations that only consider the current state of vegetation degradation.
Keywords
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