جستجوی مقالات مرتبط با کلیدواژه « ارتباطات سیمای سرزمین » در نشریات گروه « اکولوژی »

Following the unbalanced development and overexploitation of the country's watersheds, land fragmentation has become a major concern for the conservation of ecosystem services and land health. For this purpose, the present study was planned to evaluate and compare the landscape connectivity indices of KoozehTopraghi Watershed as one of the ecologically susceptible watersheds located in Ardabil Province. To this end, the landscape connectivity was investigated according to both structural and functional viewpoints, based on the green patches (rangelands and orchard) distributed at 36 sub-watershed areas. The mentioned indices were first calculated using the Fragstats Software and graph theory at each sub-watershed; then, they were standardized according to interval standardization between zero and one in order to consider the scale effect and draw a comparison in the same variation range. Therefore, the landscape connectivity was calculated, classified and mapped for each studied  sub-watershed and the whole watershed. Structural connectivity results showed the high level of landscape connectivity between green patches in all studied sub-watersheds. In addition, the results showed that the landscape connectivity was obtained with the mean and standard deviation of 0.50 ± 0.52, being varied from 0.50 to 0.97. The results also proved that out of the 36 sub-watersheds located in the KoozehTopraghi, only 15 sub-watersheds had natural lands (orchard and rangelands). Also, the sub-watershed 27, with the highest value of landscape connectivity (0.97), had the highest priority.

The Baluchistan Black Bear (BBB), a critically endangered subspecies (CR), is distributed in the southeastern Iran. Modelling of landscape connectivity of the BBBs among habitat patches can be insightful for the conservation managers working in Iran. Our study was designed to identify the potential corridors among 31 habitat patches of the BBBs in Iran using the circuit theory method. Habitat suitability map was generated in MaxEnt using 101 presence points and nine environmental variables, which were later inversed and used in corridor modeling. By using the circuit theory method, areas of high migration density were compared with four clusters determined in a previous study based on the least-cost model. Three main clusters with the high migration density of BBB were detected. Moreover, we identified eight insular habitat patches of the species that required urgent management actions to connect with other patches in the southeastern Iran. Circuit theory method clearly confirmed the main clusters introduced for the conservation of the BBBs in the southeastern Iran. Results of this study could be, therefore, used as a suitable pattern for the conservation priorities of BBBs habitats in this part of Iran.

Despite the importance of central Iranian desert as a refuge for threatened carnivores, conservation strategies for these species have been hindered by scarcity of data on distribution and habitat connectivity. The present study aimed to 1) determine the ecogeographical variables affecting distribution of three fox species including sand fox (Vulpes rueppellii), Blandford’s fox (Vulpes cana), and red fox (Vulpes vulpes); 2) identify important core habitats and dispersal corridors of the three fox species; and 3) evaluate habitat patch importance to landscape connectivity. At first step, ensemble models were built for each species using three distribution algorithms and 12 ecogeographic variables. Distribution of the foxes was affected by annual precipitation, shrubland density, human settlement density and topographic roughness. In the next step, negative exponential function was used to convert ensemble distribution maps to resistance surfaces. Core patches and significant corridors were predicted using resistance kernel approach. Most of the habitat core patches were located in Protected Areas (PAs), which could be related to high landscape resistance outside the areas under protection. Finally, the importance of identified core patches was evaluated using graph network. The patch importance to connectivity was significantly correlated with core extent, mean of relative density of dispersing individuals and probability of occurrence in patch. Results showed that the habitat quality indices are more effective than habitat quantity in predicting landscape connectivity. The obtaining results suggest that effective conservation of carnivores demands for an integrated landscape management aiming at functional connectivity among habitat patches.

Modeling of ecological connectivity across landscape is important for understanding a wide range of ecological processes. Modeling ecological connectivity between habitats and incorporating these models into conservation planning require quantifying the effect of spatial patterns of landscape on the degree of habitats connectivity. Recently، concepts from electrical circuit theory have been adapted to model habitats connectivity، predict patterns of movement and identifying corridors. Circuits are defined as network of nodes connected by resistors (electrical components that conduct current). the application of circuit theory to ecological problems is because of connections between ecological and electrical connectivity: as multiple or wider conductors connecting two electrical nodes (in parallel) allow greater current flow than would a single، narrow conductor، multiple or wider habitat swaths connecting populations or habitats also allow greater movement between them.. This theory treats landscape as a conductive surface and creates a network by converting pixels to nodes and connecting them to their immediate neighbors. Results of this theory are current and voltage maps، which can be related to ecological processes like individual movements. In this study circuit theory was applied to evaluate habitats connectivity for Persian gazella (Gazella subgutturosa) and Isfahan wild sheep (Ovis omon isfahanica) between Mooteh and Ghamishloo wildlife refuges in Isfahan province-Iran. Based on current maps، movement patterns and، functional connectivity for target species was evaluated. furthermore، area important for connectivity across the study area was identified.