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

Identification of the marine mammals’ suitable habitats is one of the requirements for coastal ecosystem conservation plans in southern Iran. A total of 42 points of Finless Porpoise (Neophocaena phocaenoides) presence were collected based on direct and random observation from late autumn to late winter of 2021. Depth map was created using a logarithm ratio model with a coefficient of determination of 0.784 and along with bed slope, channel width, average channel depth and width, channel length, channel width ratio and channel depth ratio (relative to the channels connected to it) were submitted into the Maxent model as predictor variables. The porpoise habitat suitability map was produced with an area under the curve of 0.887 for training and 0.832 for test data. According to the results of the Jackknife test, depth with an S-shaped response curve had the largest contribution (50.23%) to predicting suitable habitats of the porpoise. The suitability of the porpoise habitats increased with increasing depth and average channel depth, while the probability of the species' presence decreased with increasing slope, channel width, average channel width and channel length. The two variables of channel width ratio and channel depth ratio had insignificant effects on the probability of the species' presence. Moreover, an area of 4400 ha (10.6% of the total area) was identified as suitable habitat. Since these areas cover a small percentage of the study region and commercial fishing is performed more in such deep areas than the shallow waters, it is important to protect deep waters and reduce the resulting conflicts of interest with humans, thus ensuring the long-term survival of porpoise in the region. Therefore, it is necessary to outline porpoise conservation projects in deep areas and focus on efforts aiming to alleviate conflict with humans.

Awareness of climate change impacts on suitable habitats of wildlife species is a prerequisite for long-term management of wildlife populations. In this research, we applied maxent approach to investigate the consequences of climate change on climatic habitat suitability for sand cat (Felis margarita) for present, the best, and the worst greenhouse gas emission scenarios for 2050 and 2070, throughout the country.  Modeling results indicated that nearly 18 percent of area of the country is currently suitable for the sand cat. However, only 15 percent of suitable habitats are conserved inside the protected area network. Sand cat avoids areas with high annual precipitation and prefers areas with high mean annual temperature. Under influence of climate change in lowest emission scenario in 2070, the area of suitable habitats and conserved habitats increases. In other scenarios, there are negligible decrease of suitable habitats. Therefore, it could be concluded that sand cat is the winner of climate change.

Meighan wetland is one of the valuable wetlands of Iran in Markazi Province which is known as an important wintering habitat for the common crane (Grus grus). This desert wetland has faced with several environmental challenges, in the last two decades, due to successive drought and the lack of proper management. In the current study, modeling of habitat suitability for the common crane was conducted in Meighan wetland and aquatic ecosystems of Markazi province, using 38 presence points of the crane and with nine environmental variables (climate, vegetation cover, slope, elevation, land use distance to road, rivers and villages) in maximum entropy model (Maxent). In addition, habitat destruction factors were prioritized using a hierarchical analysis process (AHP). The area under the curve (AUC) of the model was estimated 0.997, showing the high accuracy of the model. Three areas were selected as suitable habitats for the common crane including, Mighan wetland, Kamal Saleh Dam in Shazand and 15- Khordad Dam in Delijan city. An area of 4360 hectares equals to 18 percent of Meighan wetland was classified as suitable habitats for the common crane. Suitable habitats were located on the coastal margin of Meighan wetland. Central parts of the wetland and areas far from the wetland were classified as unsuitable habitats. Environmental variables including land use, vegetation type and distance to the roads accounted for the highest contributions to the model. Habitat destruction factors were prioritized using a hierarchical analysis process (AHP). The results of AHP indicated that three factors including road construction, human settlements and land use changes were the most damaging factors with the highest weights. These factors have priority for habitat restoration to improve the ecological habitat of this species.

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.

N. kaiseri, from the southern Zagros Mountains in Lorestan and Khuzestan Provinces, is characteristically different from the other two newts of the genus Neurergus (N. microspilotus and N. crocatus) occurring in Iran by a long and narrow band of yellow color with several round blotches of white color. Modeling the distribution patterns of species is a generally efficient tool to assess their ecological characteristics. In this study, we used maximum entropy, MaxEnt, a method as a tool to assess potential distribution for Neurergus kaiseri in regional scale. The MaxEnt model predicted potentially suitable habitats for N. kaiseri with high success rates (AUC Training data = 0.904 ± 0.057). According to the map constructed, four important variables had a high contribution to species presence: elevation (38%), Precipitation of Warmest Quarter (15.8%), Min Temperature of Coldest Month (10.3%) and Precipitation of Coldest Quarter (8.7) variables. According to our results in the present study, Lorestan newts prefer mountain area with low rainfall in southern Lorestan and northern Khuzestan provinces, although the species need fountains for survival and reproduction.

In the current century, the destruction and separation of the habitat has had significant ecological effects on wildlife species, particularly species that are under threat. In the meantime, the leopard has been classified as endangered (EN) species by the International Convention for the Protection of Nature and Natural Resources (IUCN). Golestan National Park, as the first national park in Iran, is divided by the Gorgan-Bojnourd road, practically into the northern and southern divisions, which has had a profound effect on the desirability of the carnivorous habitat, especially the panther. Therefore, recognizing the factors affecting the usefulness of the Leophor's habitat as a useful tool in managing and protecting the remaining habitats in Golestan National Park can help conservation managers in this effective management. In this research, for optimizing the leopard habitat model, the maximum entropy approach was utilized using 15 habitat variables and 77 species points. Eventually, after using the Maxent model, the potentiality of the Iranian leopard habitat was predicted in Golestan National Park. The obtained AUC is 0.9, which indicates the high predictive power of the model. The results of the jacknife test show that the distribution of the leopard in Golestan National Park is primarily influenced by the distribution of prey, including wild boar, wild goat, wild sheep and red deer, and then to other environmental variables including altitudes of 500 to 1000 m, distance to water resources and roads, it is dependent.

Wildcat Felis silvestris, is one of the 8 members of felids in Iran which is distributed widely across the country and is observed all over the country except forests located in north slopes of Alborz Mountains. As there is little information about the status of the wildcat and its habitat, distribution modelling of the species across the country was performed using maximum entropy algorithm (MaxEnt), which is a modelling method, based on only-presence data. Potential distribution map of wildcat and factors affecting distribution of the species were obtained using 144 occurrence records along with 10 eco-geographical variables. Performance of the model was tested by the area under the curve (ROC). The value of AUC = 0.816 for training data revealed that the model has a good possibility for producing potential habitats of Wild Cat in the country. In addition, results of Jack Knife's analysis, land- use, slope and dem out of 10 variables were identified as important factors affecting wildcat distribution in Iranian plateau. Response curve of wildcat to land-use variation showed farms, arid places and desert limit Wild Cat presence in different landscape in present study furthermore Model indicated northern slopes of Alborz Mountains are potentially suitable for wildcat distribution. Based on results of present study, systematic habitat study in order to finding environmental requirements for Wild Cat, additionally conservation planning for wildcat populations in designated regions by the model particularly protected areas away from human settlements is highly recommended.

The Hyrcanian forests are rich in terms of biological diversity. Besides, they are known to be much valuable due to geographical isolation and having the fauna and flora. However, these forests, because of the wide range of human activities, are among the most endangered ecosystems of Iran. In this study, the Great Spotted Woodpecker has been used as a surrogate for determining patches with high value of preservation. To do this, first, we gathered the habitat points in which the related species exist. Then, the environmental variables effective on the species distribution were prepared for developing a habitat suitability model for the species. The model, finally obtained, showed that the majority of forest habitats to be protected have been located in the eastern half of Golestan Province. Two variables, i.e. Normalized Difference Vegetation Index (NDVI) and altitude were known to be the most effective indices in achieving the final habitat suitability model. Referring to the results of the study, the first two altitude classes of Caspian forests, the community of oak trees and the areas with dense canopy were decided to be in priority of conservation. According to what mentioned, it is, therefore, necessary and inevitable to ecologically enrich the forests through forest proper management and make them more sustainable ecologically.

Among 4 species of fox in Iran, Branford's fox is the smallest one. The previous studies on this species are limited and not significant. Therefore we researched the main factors that affect its distribution and its potential distribution throughout Iran using MAXENT modeling based on the presence data. The presence data gathered from camera trap pictures and some of the incidental observations and also several environmental variables including climatic, topographic and manmade were used for modeling. The output model indicates that rainfall in the coldest season; slope and daily temperature mean are the 3 variables that respectively have the most impact on Branford's fox distribution in Iran. Moreover 64787.5 km2 of Iran, mainly in the central region, is assumed as suitable habitat for Branford's fox.