Moslem Rostampour; Mohammad Saghari
Introduction: Each of the different exploitation and management methods in rangelands has different effects on the rangeland ecosystems functions. Incorrect and inappropriate ways of rangelands using, especially in the last few decades, have caused severe damage to the natural resources. There are a ...
Introduction: Each of the different exploitation and management methods in rangelands has different effects on the rangeland ecosystems functions. Incorrect and inappropriate ways of rangelands using, especially in the last few decades, have caused severe damage to the natural resources. There are a few researches on the effects of grazing on sand habitats of desert areas. The aim of the current research is to investigate the effect of different methods of rangeland utilization on ecological characteristics, including the percentage of vegetation cover, plant density, species richness, diversity, evenness and dominance, and species similarity in the studied rangelands.Materials and methods: This research was conducted in Outskirt, Seminomadic, Settled nomadic and Enclosure in Zirkouh, South Khorasan province. In each rangeland, the list of plant species, density and vegetation cover of each species was determined separately. Also, range condition was evaluated by modified four factors method. In addition to numerical indices, the ranking of species diversity was investigated using the Renyi diversity ordering curve. In order to check the species similarity between the four studied rangelands, Jaccard's similarity index was used, and hierarchical cluster analysis (Euclidean distance and Ward's method) was used to better display the species similarity. Finally, the relationship between vegetation cover and the number of species and biodiversity indices was tested by Pearson's correlation coefficient.Results and discussion: Based on the modified four factors method, the condition of outskirt and seminomadic rangelands were moderate and settled nomadic rangeland was poor and enclosure rangeland, has been evaluated as good. The results of ANOVA showed that the effect of grazing methods on the vegetation cover (at the 0.05 level) and the total and average species richness (at the 0.01 level) were significant. Enclosure rangeland has the highest plant cover percentage and plant density (54.73% and 80, respectively) and the settled nomadic rangeland has the lowest plant cover percentage and plant density (15% and 5, respectively). The highest species richness belongs to enclosure rangeland and there is no difference between other rangelands. Compared to other rangelands, the seminomadic rangeland has the highest proportion of native plants and the lowest proportion of increaser plants in the plant composition of total richness. The highest proportion of increaser plants is observed in settled nomadic rangelands. In terms of species diversity, enclosure rangeland has the highest Shannon-Wiener diversity index (2.03) and Simpson diversity index (0.80) compared to other rangelands. The results of the correlation coefficients of vegetation cover and the number of species and species diversity indices showed that, in general, the diversity indices and vegetation cover and the number of species have a significant positive correlation, and the species evenness and dominance indices and vegetation cover and the number of species have a significant negative correlation. The results of the Jacquard similarity index show that the highest degree of species similarity is observed between the outskirt and the settled nomadic rangelands (62%).Conclusion: The results showed that the overgrazing around the livestock pen in the settled nomadic rangeland is clearly visible and it has led to a significant decrease in vegetation cover, plant density and species diversity. Resting to rangelands (in the enclosure) and delay grazing (in seminomadic rangeland) can also enhance vegetation and biodiversity. In terms of the percentage of vegetation cover, density and plant composition, the seminomadic rangeland is located is next to the enclosure. The most proportion of forage species was observed in the plant composition of the seminomadic rangeland. If we accept the hypothesis that range enclosure causes the plant succession towards the climax stage and in range management, the sub-climax stage is always better than the climax stage, in this case, in terms of livestock and range management, the temporary settlement of nomads will be more beneficial than range enclosure.
Hanieh Khodad Saryazdi; Samira Hosseinjafari; Mohammadreza Elmi
Introduction: Railway construction is one of the important activities in the development of any country. Railway construction operations can have an impact on the environment around the railway. This study investigated the effects of Yazd-Eghlid railway construction on some vegetation and soil characteristics ...
Introduction: Railway construction is one of the important activities in the development of any country. Railway construction operations can have an impact on the environment around the railway. This study investigated the effects of Yazd-Eghlid railway construction on some vegetation and soil characteristics of artemisia and camel grass species located in Kalmand-Bahadoran Protected Area.Material and methods: In order to evaluate the vegetation and soil variables in the studied types, random-systematic sampling method was used. Random-systematic sampling method is used; Thus, within each brigade, three areas with different distances by rail include the first area (distance 0 to 250 meters), the second area (distance 250 to 500 meters) and the third area (distance 500 to 1000 meters) from Railway was considered and vegetation and soil samples were taken. Within each area, 4 100-meter transects were randomly placed and 2 plots at the beginning and end of each transect were systematically placed. The reason for comparison of more than two groups was analyzed using one-way analysis of variance and Duncan test using SPSS software.Results and discussion: The results of this study showed that the construction of a railway in the Kalmand-Bahadoran Protected Area and the measures taken during the construction process may affect the physical and chemical properties of soil and vegetation, which in the Artemisia type causes a significant decrease in the production of plant vegetative form srub (0.81 g) (P <0.05). Also, a significant decrease in electrical conductivity (0.78 ds/m), potassium (0.64), acidity (7.7),lime percentage (26.25) (P <0.05), and percentage of clay (4%) (P <0.01) was observed. In the Cornulaca type, construction of railways significantly increased production (6.13 g), density (1.42), and percentage of cover form shrub (6.01) (P <0.05). It also significantly reduced the production of shrub vegetative form (0), the percentage of shrub vegetative form cover (0.17) (P <0.05) and the density of shrub vegetative form (0) (0.01), (P <0.01). Regarding the effect of railway construction on soil parameters of this type, it can be said that railway construction causes a significant increase in the percentage of rock (93%) and a significant decrease in the percentage of silt (2%), electrical conductivity (ds / m66 (P <0.05) and also significantly reduced organic matter (0.18), phosphorus (5.25 ppm) and potassium (0.63 ppm) (P <0.01).Conclusion:The construction of the railway and activities that take place during the processes for the construction of the railway units can cause the movement of soil around the railway, whichcauses soil and water erosion in the region that may lead toa decrease in soil quality in the areas near the railway and consequently, the decrease of vegetation production in the area.
Mahmoud Ahmadi; Zahra Alibakhshi; Manouchehr Farajzade Asl
Introduction: Change detection is a process to find the paradoxical regions in different temporal imageries of a similar area. Vegetation is very effective at the absorption of grime and lead, prevention of the spread of contaminations in urban environments, clearing the air, and reduction of heat islands. ...
Introduction: Change detection is a process to find the paradoxical regions in different temporal imageries of a similar area. Vegetation is very effective at the absorption of grime and lead, prevention of the spread of contaminations in urban environments, clearing the air, and reduction of heat islands. The need to investigate the decrease or increase in vegetation is extremely important in Tehran as a metropolis, as well as its satellite counties because of the increase in population and construction. The purpose of this research was to investigate the spatiotemporal changes in the vegetation of Tehran and its satellite cities in association with temperature during different temporal periods. The results of this research can be useful in studies concerning urban viability, reducing the effects of urban heat islands, and environmental sciences. Material and methods: Initially, the extraction and preparation of data were carried out using the ETM+ sensor of Landsat 7 satellite from 2001 to 2015, with June being selected as the hottest month of the study area. Then, the selection of days to be studied and correcting imagery, preparing LULC maps and plotting the area percentage was done. The computation of vegetation indices and built-up areas and the calculation of land surface temperature along with the assessment of the accuracy of surface temperature data were other stages of the research methodology. Finally, the area percentage of each index, as well as the scatter plot and Gaussian function chart were produced and the spatial variation of vegetation was studied. Results and discussion: According to the land use and land cover map (LULC) in 2001, 2005, 2010, and 2015, the vegetation significantly increased in 2015 compared to previous courses. The development of the residential area in the west region was higher than in other regions. In the charts of the area percentage for each land use class and its change over the four selected years, the vegetation percentage has been decreased since 2001, which continued in 2010 and 2015. In this study, the relationships between surface temperature and NDVI and SAVI indices were not linear, which showed that there is another controlling factor. In the normal density function chart, which is usually described by mean and standard deviation, variations of NDVI and SAVI indices were similar in the second and third periods, and the mean increased in these two periods compared to the first period, and the height of curve increased due to the reduction of variance. In this study, the results showed a decrease in the value of LST in the second and third periods from 2006 to 2015. On the other hand, the vegetation area was increasing in the region. From a spatial point of view, Tehran has the highest percentage of class one of NDVI that have no vegetation surfaces. Conclusion: Regarding the study of NDVI, SAVI and NDBI indices, the overall trend of vegetation cover in the study area was increasing. Considering the values of 15R2"> , the vegetation in Ray County was defunct. In the cities of Robat Karim and Tehran, vegetation cover was increasing. The high growth of satellite towns in the surroundings of Tehran has led to the allocation of land and fields and vegetation to residential areas, which exacerbate the heat islands and the unfavorable conditions of life.
Seyyed Shahab addin Tayyebi; Shahindokht Barghjelveh; Mojtaba Soleimani-Sardo
Introduction: Enhanced consumption of fossil fuels has increased the amount of carbon dioxide in the atmosphere, which is one of the most important causes of urban pollution, as well as global warming. The development of plant cultivation and the creation of green spaces is one of the most effective ...
Introduction: Enhanced consumption of fossil fuels has increased the amount of carbon dioxide in the atmosphere, which is one of the most important causes of urban pollution, as well as global warming. The development of plant cultivation and the creation of green spaces is one of the most effective methods for carbon storage. Several studies have been conducted to determine the ability of different plants to reduce carbon contents of the atmosphere, many of which recognized the high efficiency of some plants in carbon storage. The aim of this study was to investigate the ability of Petunia hybrida and Tagetes patula in terms of carbon storage, as two key species in Kerman green space developmental projects. Therefore, the results of the present study can be used for urban green space designing with a focus on carbon storage. Material and methods: In this study, the organic carbon content of the samples was determined by an S-N-H-C element analyzer after collecting, weaning and weighing. Subsequently, after surveying the field and taking into account the traffic nodes, the target areas were identified by measuring the highest rates of pollution in certain regions of the Kerman city. Finally, by assessing the green spaces of Kerman, the urban ecological map was prepared for carbon storage. Results and discussion: The results of this research indicated that the carbon storage ability of Petunia hybrida is more than Tagetes patula. Therefore, we suggest that in the western regions towards the center of Kerman city, which had more traffic nodes, Petunia hybrida should be chosen for the development of green spaces. Conclusion: Since the components of green spaces have unique roles in urban spaces, assessing and understanding the potential capacity of green spaces are so crucial for designing suitable programs for reducing the environmental problems of urban spaces. This study showed that by understanding the capabilities of components of green spaces, we can decrease some urban challenges. Consequently, the cultivation and development of Petunia hybrida will cause more carbon storage than Tagetes patula. Considering the benefits that these kind of plants provide, they should be considered in green spaces’ developmental plans.