نشریه مرتع و آبخیزداری
سال هفتاد و ششم شماره 2 (تابستان 1402)

Groundwater is important water resource supply, especially in arid and semi- arid regions. Increased utilization of the ground water aquifer leads to significant reduction in the storage of reservoirs. This study evaluates the hydrogeological drought in Garmsar plain using Groundwater Resource Index (GRI). First, we used 17 piezometric wells data over 2001-2011 statistical period to calculate GRI in the beginning, middle and end of the period. So, we used different interpolation method including geostatiscal method ordinary kriging (OK), simple kriging (SK) and deterministic methods including inverse distance weighting (IDW) to prepare the maps over three periods. The mean absolute error (MAE) and root mean square error (RMSE) indices were used to evaluate the accuracy of simple kriging, ordinary kriging and IDW classification based on the drought maps. The results showed that the values of MAE and RMSE criteria for simple Kriging is better than the other methods and indicates the suitability of this method for zoning GRI. According to the results, the most severe hydrogeological drought in Garmsar plain was at the end of 2011, that 91.16 % of the study area was suffered from severe drought. SPI was used for considering the effects of meteorological drought in the time scale of 3, 6, 9, 12, 24 and 48 months on groundwater. The correlation between SPI and GRI showed long-term timescale of 48 monthly has the greatest correlation with groundwater level.

Degradation of the Earth's biodiversity has resulted in damage that in many cases is irreparable to humans. The purpose of the present study is to determine the boundaries and environment of the proprietary and medicinal species of Kozal Damavandi (Diplotaenia damavandica Mozaffarian, Hedge & Lamond). This plant has received a lot of attention due to the presence of special effective compounds that have therapeutic effects on most skin complications. For this purpose, a habitat map was first prepared with local visits and previous reports. Then, its environment including physiography, accompanying species, lithology, soil and water resources characteristics were studied. The results showed that this plant species grows at the altitude of 2400 to 3600 meters above sea level, with a slope of above 60% and an altitude of above 35ᵒ 40’. Lithological study of the habitat area in dense areas shows the thick green tuffs, Jeirood foundation, shale, and dark sandstone. Also, in terms of soil science, there were significant differences between the examined parameters of K, P, and SO4, while regarding the water resources the significant parameters are Cl and NO3. Investigating the deterioration of vegetation also showed that the highest coverage density in the region was in 2014. The results of the present study will be used to determine the limiting factors of the habitat and to investigate the possibility of the growth of this exclusive species.

Land use changes in countries like Iran, which is facing space limitations, should be thoughtful and in accordance with proper planning, just like water consumption. On the other hand, the inherent dynamism of human beings and their needs has made the way and extent of land use change over time. Therefore, the aim of this research is the dynamic modeling of land use changes based on the human-environmental system in Taleghan watershed. For this purpose, land use maps for the years 1994, 1999, 2002, 2009, 2014, 2019 were classified into six classes of pasture, forest, agricultural land, barren land, residential land, and water using Landsat satellite time series images. After the validation of the maps and the detection of changes, under the three scenarios of current economic growth, rapid economic growth and sustainable development, simulation was carried out until 1435 using dynamic system modeling. The results of detecting land use changes during the period show that the trend of changes in agricultural lands, pastures, forests, has been decreasing, and barren lands and residential areas have always had an increasing trend during the survey period. The results of the simulation show that among the three scenarios examined, the sustainable development scenario of coordination between the amount of land utilization and meeting the needs of the community and economic growth has been acceptable. Therefore, it can be concluded that the sustainable development scenario is an important basis for land use planning in the coming years in order to reduce the destruction of natural resources and maintain a stable state in it, and this scenario will bring favorable economic growth in the future.

Rangelands played an effective role in the country's economic and political development prior to its dependence on oil and its derivatives. Therefore, paying attention to the environmental and social stresses brought to these ecosystems highlights the need to use new technologies to diversify production sources and reduce costs. This study was conducted at the Taleghan range station with the aim of financially evaluating electric fences to encourage pastoralists to use this technology in rangelands. For this purpose, the income from the fencing project was investigated. The financial evaluation of the electric fencing project and the time period for its capital return in 2016 was done using the equations of net present value, benefit-cost ratio, internal rate of return, and net present value criterion at different discount rates. The total fixed and current costs of this project were equal to 330 million rials. The income from animal meat production, medicinal plants, the added value of electricity production, the income from the replacement of shepherds, and the net income were equal to 73%, 23%, 7.5%, 103%, and 120% respectively. The criterion of net present value at different discount rates was equal to 127%. Considering the economic nature of fencing technology and the existence of economic benefits resulting from it in the form of a wide spectrum of ecosystem services for the beneficiaries of rangelands, the importance of promoting the use of new technologies in rangelands to maintain and support the production chain of rangelands is highlighted.

In recent years, the use of digital soil mapping (DSM) based on machine learning algorithms with the aim of preparing soil maps has become widespread with the basis of soil class prediction with the help of modeling the relationships between them and environmental variables. One of this method's challenges is the imbalanced nature of soil distribution in landscape, which leads to overfitting and underfitting of classes, and as a result, reduces the accuracy of many used models. This study was conducted to evaluate the ability of two machine learning algorithms, including random forests and support vector machines, for the digital mapping of soil classes with an imbalanced data set. This study was conducted on 95 soil profile classes at the family level, in 4000 hectares of land in the Honam sub-basin, Lorestan province. The issue of imbalance in soil classes was investigated by using six data sets, including the original soil data set and five data sets created by several resampling approaches including two manual classifications and three over-sampling, under-sampling, and Synthetic Minority Over-Sampling Techniques in the R software. The results showed that despite the low values of overall accuracy, the Geographical distribution of soils with high frequency in the study area in digital soil map obtained from the random forest and the original data set as well as Synthetic Minority Over-Sampling Technique, with conventional soil map of study area is significant. Therefore, the low observation number of other soil classes and as a result incorrect training of models can be considered as one of the main reasons for the low accuracy of the used models.

The positive economic and social effectiveness of rangeland restoration projects activates the process of sustainable development and leads local communities to sustainable prosperity. The purpose of this study is to assess the socio-economic and environmental effectiveness of restored rangelands with Atriplex canescens plantation in Mallard county, Tehran province, Iran. The descriptive-analytical research method based on questionnaire was applied within the statistical population including 65 experts, 132 pastoralists and 29 local communities. The selection of samples was random and sample size were determined using Cochran's formula for three groups of experts (55), pastoralists (99) and local communities (27). To determine the validity of the questionnaire, a group of experts were used and Cronbach's alpha coefficient was used to estimate the reliability of the questionnaire. Also, Kruskal-Wallis test was used to compare opinions of the studied statistical societies. The results of the comparison of economic, social and environmental indicators showed that A. canescens plantation had a significant effect on social index and had no effect on the other two indicators. Social- environmental effectiveness of planting A.canescens is related to increasing livestock products and improving the condition of ranching, According to pastoralists, the greatest economic, social and environmental effectiveness from planting A.canescens has been related to increasing livestock products and improving the condition of ranching, increasing the level of public awareness. In general, results of effectiveness planting from the point of view of all three groups are close to each other and they often agree on the effectiveness of planting Atriplex. This alignment in thinking of plantation will lead to success in the implementation of projects and the achievement of goals and perspective,.