جستجوی مقالات مرتبط با کلیدواژه « پراکنش » در نشریات گروه « محیط زیست »

This study aimed to introduce and generate a distribution map of mesquite (Prosopis juliflora) across the Sahara-Sindhian region of Hormozgan province. Mesquite distribution was determined in three stages: Collecting information from the General Department of Natural Resources and Watershed Management of Hormozgan Province, conducting field visits, and digitizing polygons of mesquite distribution for mapping. During the field surveys, the geographical coordinates of the mesquite's natural presence and afforestation areas were recorded based on the elevation range. This plays a significant role in its distribution. The boundaries were identified on Google Earth images as polygons, and the area was calculated using ArcGIS Pro software. In Hormozgan province (Beshagard, Hajiabad, and Bastak), it is found as a single tree or scattered at low altitudes. Mesquite's total area of afforestation and natural forest (canopy cover higher than 5%) is 19275.34 and 18883.21 ha, respectively, accounting for 0.56 of the province's area. Also, mesquite is distributed as a single tree (canopy area lower than 5%) in 48.64 percent of Hormozgan province. The largest afforestation area for mesquite is in Jask City (for stabilizing flowing sand). Mesquite is naturally found in Jask, Sirik, Minab, Banda Abbas, Parisian, Khamir, Bander-e-Lengeh, and Gheshm, respectively. Vast mesquite areas in this province indicate favorable conditions for species regeneration and growth. According to the easy regeneration and fast distribution of P. juliflora in Hormozgan province, it is suggested that native species be used in afforestation.

Chondrostoma is a genus of the family Leuciscidae. Members of this genus have not been studied in Iran. During the years 2013-2021, Chondrostoma samples were obtained from the Caspian, Tigris, Isfahan and Kor basins using electrofisher and gill net. ArcMap 10.7 were used to create distribution map of this genus. IUCN Red List criteria v. 3.1 and GeoCAT software were used to assess the conservation status. The Cytb gene of the samples was amplified using a thermocycler and sequenced after purification. The phylogeny tree of the studied samples were drawn by Mrbayes and RaxML. In 87 stations of Tigris, Isfahan and Caspian basins, members of the Chondrostoma genus were found. According to the IUCN Red List, C. cyri and C. regium were the Least Concern and C. esmaeilii and C. orientale were placed as Critically Endangered. The highest genetic distance of 4.74 were calculated between C. esmaeilii and C. cyri and the lowest genetic distance of 1.40 was calculated between the two populations of C. regium in Asi and Tigris River drainage. According to the results of phylogenetic tree, monophyly in the genus Chondrostoma were not proven. Due to the absence of Squalius berak and Alburnus sellal at the type locality of C. esmaeilii and its haplotypes next to other species of the genus Chondrostoma in the phylogenetic tree, the hybrid hypothesis is not approved.

This research was carried out based on ecological monitoring of the Caspian Sea in depth of 30 meters project during 2018-2019. Sampling from the bed sediments of the southern Caspian Sea in 8 transects including Astara, Anzali, Sefidrood, Tonekabon, Nowshahr, Babolsar, Amirabad and Turkmen was done by a cat sampler. Sampling was done seasonally. The aim of this study was to investigate the species diversity, density and biomass and local distribution of different macrobenthos species. A total of 16 species were identified, belonging to 7 families which of Polychaeta, Crustacea and Bivalvia were found. In addition, Oligochaeta have been identified. The polychaeta comprised 59% of the total macrobenthos density. In contrast, Cerastoderma glaucum, although the frequency was 6.3% of the total density of macrobenthos, but comprised 59.9% of the total biomass. The results showed that the diversity indices had the highest value in spring and the lowest in summer. Polychaeta had the highest local distribution (100%) and Malacostraca Pterocuma sowinskyi and Cardiophila baeri had the lowest (8.2%). The lowest and highest mean (±SE) densities were recorded in winter and spring with 408±81.1 ind.m-2 and 1225±246.2 ind.m-2, respectively. In conclusion, the increase in biomass of bivalve molluscs versus the decrease in density can be due to the large size and having oyster shell and the increase in diversity indices in spring can be due to the presence of different species for reproduction after wintering period which is consistent with the density of macrobenthos in the spring.

In this paper biocultural diversity, its assessment and conservation has been investigated by reviewing different articles. The most striking characteristic of life on earth is its enormous diversity which is formed not only by the variety of plant and animal species and ecosystems, but also by the variety of cultures and languages in human societies. However, currently both biological and cultural diversity are showing an unprecedented rate of decline in human history. Studies in late 20th century have demonstrated that there is a direct link between distribution, threats and loss of these diversities on both regional and global levels. Increasing awareness of commonalities and linkages among biological, cultural and linguistic diversity and realizing the fact that breaking down of these linkages underlies many of the environmental and social problems humanity faces today; have led to the development of a new field named "biocultural diversity".  In this regard, many researches have been completed in different countries as well as in the world, the main lines of which can be grouped as: global and regional analyses of the correlations between linguistic and biological diversity; tools for measuring and assessing the state of biocultural diversity; and studies about the persistence and loss of biocultural diversity. It seems therefore that carrying out such studies in Iran considering its biological and cultural diversity, could be of higher importance.

Sand dune seas and dune fields or ergs are the results of the wind erosion process in the sedimentation phase, although they are also observed in the transport area. It is crucial to prepare a map of wind sediment dispersion in the country from the point of view of wind erosion, the challenge of fine dust, and the damages caused by their movement. So far, various statistics have been presented on the area of windy sand unevenness of the country. To study the distribution and other features of the country's sandstones, as well as to prepare spatial databases using digital images (Landsat, IRS, and Google Earth database), aerial photographs (1993-2003), and field operations, a new map of their distribution in 20 provinces of the country was determined. The results showed that the area of sand fields in the country is about 4.7 million hectares, which is the highest in Kerman province (1224512 hectares) and the lowest in Tehran province (73 hectares). Yalan or Lut with 1458320, Jazmourian with 566326 and Jan with 477880 hectares are the three largest sand dunes in the country, respectively. There are differences in the area of sands in the country.

The striped hyena (Hyaena hyaena) is a global scale endangered species and has a high risk of local extinction in its population, therefore, investigation and evaluation of its habitat for covered areas seems necessary. This study was done to investigate the distribution status of this species in the Shaho Mountain domain in Kermanshah province. In this study, after collecting species presence points, habitat variables including slope direction, elevation, distance from rangelands, distance from agricultural land, distance from main road, residential density, ecotone, slope percentage and viewshed was identified and used in the analysis. In this regard, firstly, using single-class support vector machine models the habitat of the species was modeled. By confirming the validity of the model output through AUC criteria was used from the binary output of the model in order to provide quasi-absence sites 10 times the presense points within almost 5 km distance. Then maximum entropy models (MaxEnt), Back-Propagation (BP) Neural Network model (BP-ANN), and two-class support vector machine (SVM) were then used for modeling. The validity of which were calculated as 0.97, 0.97, 0.89 respectively. Then, all models were used in an aggregation scenario according to the weight obtained from model validation (AUC). Model sensitization was performed using random forest method. The results showed that the variables; viewshed, road distance and distance from the fields were the most important habitat variables affecting the striped hyena habitat in the region.

The present study aimed to the biodiversity of Chondrichthyes and distribution of this group of aquatic animals in the Persian Gulf and Oman Sea using biodiversity indices and finally, the maps were ploted using the GIS software. Data collection was carried out from October to December 2018 using bottom trawler by Ferdows from Sistan and Baluchestan and Hormozgan provinces waters in the Persian Gulf and Oman Sea. A total of 4014 specimens were caught in the study area, of which 245 specimens belonged to 10 species and 4 families of sharks and 3769 specimens belonged to 21 species and 12 families. The results showed that Margalef species richness index varied from zero to 1.82 for sharks and from zero to 2.65 for batoids. Also, the Pielou’s evenness index varied from 0.43 to 1 for sharks and from 0.11 to 1 for the batoids. Also, the Shannon index varied from zero to 1.9 for sharks and zero to 1.86 for batoids. The Shannon Diversity Index distribution for sharks only showed a range of 54 to 56 degrees longitude (range south of Qeshm Island to Bandar-lengeh) as a hotspot compared to the rest of the study area. On the other hand, the distribution of this index showed two points, range from 57 to 59 degrees longitude (Sirik to Meydani) and of 53 to 55 degrees longitude (Kish Island to Qeshm Island) as hotspots for the presence of batoids.

The two- spotted mite Tetranychus urticae Koch is one of the cosmopolite pests, which attack many agricultural and greenhouse plants. The Maximum Entropy model (Maxent) was used to potential distribution in 70 stations (orchards) of Tehran provinces. Distribution model was obtained using out of 19 environmental variables that only six environmental predictors and presence records had a greater impact on this species were used in the modeling. The accuracy models were also evaluated by the area receiver operating characteristic curve (AUC) value. According to the Jacknife test, rainfall variables of the warmest season of the year and the maximum temperature of the warmest month of the year were the most contributing in two-spotted spider mite distribution modeling in Tehran province that the rainfall of warmest season was more important. The AUC values, based on training data, was 0.75 confirning the high accuracy of Maxent in predicting the distribution model of two-spotted spider mite.

Recently, pollutant particles, in particular suspended particles with a diameter of less than 2.5 microns, have been the most common pollutant in Tehran. One of the most important processes to solve the problem of suspended particles is to obtain appropriate information on the distribution of these pollutants at different time periods. The goal of this study is to propose a spatial approach for modeling and analyzing the spatial and temporal distribution of suspended particles based on GIS analyzes.

At first step, PM 2.5 and PM 10 pollutants was collected from Tehran Air Quality Control Company. Then, the accuracy of different interpolation methods was evaluated. Finally, the IDW method was selected as the best interpolation method for plotting the concentration of these pollutants in Tehran

Daily, Monthly average and annual average concentrations map were prepared according to the daily data of these pollutants in the years 93 and 94. As a result, spatial and temporal analysis of distribution of PM 2.5 and PM 10 contaminants in Tehran was made
Discussion and conculation: According to the performed study, it can be said that the highest concentration of PM10 pollutants is found in the southwest of the city and the highest concentration of PM 2.5 pollutants is found in Shahr-e-Ray and central part of the city.

Among the 57 genera, Astragalus genus with 3494 species is the biggest herbal genus all over world. Astragalus species have certain genetic characteristics due to their wide distribution in the world. This study deals with the diversity, distribution and ecology of this genus members in the world.

Brown Bear is the country's largest species in carnivorous which is distributed in a wide range of Alborz and Zagros mountains. Its distribution range in the western part of the country reaches Lorestan province. Sephid-Koh protected area with its vegetation, its breadth and ecological condition has created a good habitat for this species. In order to identify the range of distribution and favorable habitat of this species in the mentioned area, the presence points of species were collected in spring and summer seasons of 1396. 14 effective variables in the distribution of the species were identified. After performing the multicollinearity analysis, 4 variables were omitted due to variance inflation index (VIF) more than 10 and modelling was performed by using 10 habitat variables, 10000 randomized background points and 500 iterations in MaxEnt software. The significance of variables in modeling was done using jackknife analysis. In order to obtain habitat binary map, threshold of the LPT (Lowest Presence Threshold) was used the results of the model validation showed that the model was successful in the average run (AUC = 0.85); and the habitat variables of distance from human settlements, sub roads and altitudes had the most effect on species distribution. Based on the findings, 65% of the Sephid-Koh area is suitable for the brown bear. Regarding the distribution of species in the region, this species can be considered as a health index and a key species of the Sephid-Koh region.