elahe zafarian; Ataollah Ebrahimi; Reza Omidipour
Abstract
Land cover mapping is essential for natural resource management. Satellite imagery can be used for mapping land cover. Several methods are available for land cover mapping whilst choosing the best method is one of the most important issue in this context. To compare pros and cons of three methods of ...
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Land cover mapping is essential for natural resource management. Satellite imagery can be used for mapping land cover. Several methods are available for land cover mapping whilst choosing the best method is one of the most important issue in this context. To compare pros and cons of three methods of classification including maximum likelihood, object-based segmentation and artificial neural network, first, the efficiency of these three methods were evaluated. Then the trend of land cover changes in Shahrekord basin was investigated for 1999, 2009 and 2015 using Landsat images of TM, ETM+ and OLI sensors, respectively. After geometric and radiometric corrections, the land cover map of 2015 was prepared based on the three methods. The results of the validation mapping methods revealed that object-based method was more promising than the others with 93 and 90% for total accuracy and Kappa coefficients of agreement, respectively. So, the object-based segmentation method is recommended for monitoring of land cover changes. The results of the land cover change indicated that residential areas increased from 1.727% in 1999 to 2.98% in 2015 and agricultural lands increased from 5.73% to 12.60% but rangelands were decreased by 9.05 in total. Moreover, bare-lands were increased from 1999 to 2009 by 6.19% but decreased from 2009 to 2015 by 5.27%. The result of this study showed that the object-based method is superior to pixel based method of Maximum-liklihood and neural network. So, object-based segmentation is recommended for estimating land cover changes.
Reza midipour; Reza Erfanzadeh; Marzban Faramarzi
Abstract
Intensive livestock grazing is one of the most important destructive factors in rangelands that leads to decrease of diversity and causes disappearance of sensitive plants. On the other hand, considering the scales in assessment of diversity is very importance to study the variability of plant diversity ...
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Intensive livestock grazing is one of the most important destructive factors in rangelands that leads to decrease of diversity and causes disappearance of sensitive plants. On the other hand, considering the scales in assessment of diversity is very importance to study the variability of plant diversity patterns in different scales. Therefore, current study aimed to investigate the impact of livestock grazing on diversity components in different scales using additive partitioning methods in western country rangelands in the Ilam province. Sampling was carried out in 40 plots of 4m2 in 8 rangeland sites including 4 exclosures and 4 grazing sites. Based on additive partitioning diversity methods, the total diversity was partitioned into additively components within and among samples. The results showed that diversity among sites (β2) had the highest contribution of total diversity that indicated the importance of this scale for conservation practices, and it was due to the variation of composition between sites. In addition, the results represented that exclosure in the semi-arid areas can increase diversity at plot scale, while in the regional scales (diversity among sites or β2) livestock grazing leads to increase in diversity. Therefore, exclosure of rangelands does not necessarily lead to increase in diversity. Also, long terms exclosure can lead to increase evenness that resulting in increasing competition among plants, therefore it could decrease plant diversity.
