نشریه مرتع و آبخیزداری
سال هفتاد و ششم شماره 1 (بهار 1402)

Reliable estimation of precipitation is one of the most essential needs in water resources management. However, in many parts of the world, especially in Iran, the lack of time and place of rainfall data is very noticeable. Therefore, the use of satellite information is one of the ways to compensate for the lack of information. The purpose of this research is to compare the accuracy of rainfall information of TRMM-3B42 and PERSIANN-CDR products on a daily scale. The products of these two satellites are available daily for free in the pixel size of 0.25 degrees. The daily rainfall of 12 stations in the southern slopes of Alborz in a statistical period of 2000-2014 was used. The results show that these two satellite products are not the same in different statistical parameters, so that CDR and 3B42 have estimated 100% and 25% more rainfall events than the stations, respectively. Also, PERSIANN satellite is significantly superior to 3B42 in terms of RMSE, POD and CSI parameters, but on the other hand, it is weaker in terms of Bias and FAR parameters. Therefore, the selection of the desired satellite product should be based on the proper parameters.

This study aimed to investigate the effect of Juniperus sabina (evergreen) and Berberis integerrima (deciduous) and herbaceous patches on some soil properties (pH, EC, aggregate stability, microbial respiration, organic carbon and nitrogen) in their habitats. In June, when maximum growth of the dominant plant species in rangelands of central Alborz was occurred, of each plant patch, 10 patches were randomly selected and soil were collected beneath of the canopy species in each from two depths: 10-0 and 20-10 cm (in total 60 soil samples). Then, soil physico-chemical characteristics were measured in the laboratory. In order to examine the differences between each soil characteristics associated with patches and depths, two-way ANOVA using GLM was applied. In addition, one-way ANOVA and post-hoc tests were used to compare soil characteristics between patches, in each depth separately. The results showed different effect of different patches on the soil characteristics. In upper soil layer, the highest contents of organic matter (4.62%) and aggregate stability (36.08) were observed under J. sabina, while the highest total nitrogen was found under B. integerrima. In deeper soil layer, the highest content of organic matter (5.19%) was found under J. sabina. The highest microbial respiration contents in both depths were observed under herbaceous patch. The variation of other soil characteristics were less pronounced by type of patches. In general, the results of this study cleared that different woody plant species have different effects on soil characteristics, should be mentioned in the rangeland development and improvement projects.

Different forms of land use development and human activities in protected areas are considered to be the main drivers of change, which have many effects on habitats, habitats, diversity and richness of species. The purpose of this research is to model the effect of human activities on the diversity of vegetation using the artificial neural network method and determine the impact of ecological and human variables on them. This research was done in the Central Alborz protected area under the management of Alborz Province. To achieve the mentioned purpose, firstly, 101 plots and 101 soil samples were collected and, soil and vegetation analysis were performed on the samples. Finally, using the multilayer perceptron neural network method and using 18 input variables including physical and chemical variables of the soil, physiographic variables, and human factors variables , the effect of human activities on the diversity of vegetation in the study area modeled. According to the results, the vegetation diversity model with the structure of 1-5-18 according to the highest value of the coefficients of determination in the three categories of training, validation, and test data is equal to 0.82. 0.81 and 0.68 show the best structure optimization performance, distance from roads, electrical conductivity, and percentage of organic matter in the soil show the greatest effect on the diversity of vegetation in the study area. The model presented in this research is used as a decision support system in evaluating the effects of human activities on the diversity of vegetation in protected areas and provides the possibility of predicting the extent of these effects on the diversity of vegetation in these areas.

Climate change is one of the main determinants of plant species redistribution and biodiversity loss. This study aims to predict the impacts of climate change on the geographic distribution of Agropyron intermedium in Chaharmahal-va-Bakhtiari province as a part of Central Zagros, Iran. The presence points of studied species were recorded from our field surveys in the studied area. In this study, we used the ensemble predictions based on five species distribution models. The future projections were made for the year 2070 with three scenarios SSP126, SSP370, and SSP585, and two general circulation models GFDL-ESM4 and MRI-ESM2-0. According to the results, Random forest model and the generalized boosted model were recognized as the most reliable models for predicting species distribution. The most effective variables in the suitability of the A. intermedium species habitat were, respectively, elevation, Precipitation of wettest month, and slope. According to the finding, about 21.26% of the study area for A. intermedium species have had suitable habitats. The decline of suitable habitats of A. intermedium will be 36.06% to 63.20% under the GFDL-ESM4 general circulation model and 36.69% to 65.17% under MRI- ESM2 general circulation model due to climate change. The results also indicated that climate change will alter the range size of studied species and will probably shift to higher elevations in the future. The results of this study can be used to protect the habitat of the range plant species, as well as its rehabilitation and restoration.

Accurate slope map and the governing river network of a river basin are key inputs of hydrologic models. The purpose of this study was to investigate the effectiveness of the PriorityFlow tool in topographic data processing with the aim of improving slope map extraction in the eastern Faryab Basin. PriorityFlow is a tool in the R programming environment, which aims to generate the correct slope map and to form a network of continuous pathways that matches the observed river network. To process the digital elevation model and prepare the slope map, three input files were used, including the digital elevation model, the representative map of the watershed and the representative map of the observed river network of the study area. After producing the slope map using this package, the obtained results were compared with the outputs obtained from other traditional tools available in the Parflow hydrological model. Specifically, the river network map related to the two slope maps were extracted by the Parflow model under the condition of very low permeability of the domain surface and compared with the observed river network of the study basin. The results showed that the slope map produced by the PriorityFlow tool has led to the production of a more accurate river network that matches the real river network of the eastern Faryab basin. Also, this software package is able to produce the slope map with enhanced accuracy and based on non-diagonal connections along the cell levels in the digital elevation model of the study area.

The desert environment is aeolian, being dominated by the wind. The dynamics of wind erosion are driven by both natural processes, including climate and its fluctuations, and human activity. Separating the climatic and anthropogenic causes of wind erosion can improve the understanding of its driving mechanisms. The aim of current research is to evaluate the spatio-temporal dynamics of the aeolian process based on the sand dunes morphology and the analysis of the spatial correlation between wind erosion dynamics and climate fluctuations. Based on meteorological, remote sensing and field observations data, the impacts of climate fluctuations on the temporal and spatial changes of the aeolian process were evaluated according to the indicator of the creation and expansion of sand dunes .MODIS remote sensing data was used to study the sand dunes morphology. The temperature, precipitation, wind speed and other meteorological data used in this study were all derived from two synoptic stations of Qom and Kashan. The analysis of the elongation and form of the sand dunes as the wind direction indicator showed that the studied area is affected by the winds region of the Qom (northwest and west). The results of climate studies showed that over the last 27 years, the region has a rising temperature trend, while the average precipitation in the region has decreased in the same period. The relationship between drought conditions and aeolian process showed that the region experienced severe drought conditions more than normal or abnormally dry conditions during 1369 to 1395.