Assessment of landscape connectivity indices and habitat quality to identify essential habitat patches for Ovis orientalis × Ovis vignei (a case study: Varjin Protected Area, Tehran)

 Landscape connectivity plays an essential role in the conservation of protected areas. The Alborz wild sheep (Ovis orientalis × Ovis vignei) is the dominant species in Varjin Protected Area. The population of the species has been decreased during the last 20 years due to habitat loss and fragmentation. So far, many studies have been done on the environmental impact assessment of urban area developments on the protected area, but there is still a lack of habitat connectivity and quality analysis in the area. Based on the spatial location of Varjin Protected Area, connectivity analysis can help conservation planners to identify key patches and corridors that more than others, contribute to upholding species dispersal. The aim of this research is to prioritize habitat patches for conservation by analyzing the connectivity of the habitat patches and considering habitat quality as the second important factor in species distribution. Applying this method could lead to better conservation prioritization between habitat patches.

 Landsat satellite images 7 and 8 have been used as inputs for the Habitat Quality model and Connectivity analysis. The connectivity metric was analyzed by calculating the probability of connectivity (dPC) and betweenness centrality (dBC) at different spatial scales of landscape and patch. All the analyses have been done in Graphab open-source software using graph theory and applying network analysis containing nodes and edges. The threshold was pre-defined for the species, and all the calculations were based on Euclidian distance. This research used the InVEST Habitat Quality model to analyze the spatial status of habitat quality. Finally, spatial analysis was performed by ArcGIS 10.4 and the maps were classified based on natural breaks.  

 Results demonstrated that the value of dPC was between 0 to 0.796, and the value of dBC varied from 0 to 7.58E+11. Different importance values have been obtained for all 23 patches. This suggested that patches 1 and 4 showed the highest dBC and dPC metric values. The values of InVEST habitat quality decreased in the south and northeast of the area, respectively, due to proximity to urban areas and other threats. Patches with good performance in improving connectivity and higher habitat quality values were identified. By overlaying the output values of the maps, prioritized patches were recognized and suggested to be placed under protection.

 Patches with a high level of connectivity and habitat quality were located in the east and southeast of the region. This research has taken a novel step toward conservation by using connectivity analysis and habitat quality as an ecosystem service in protected areas. Landscape and patch scales as two spatial indices can be used in other regions and for other essential species. As the Varjin Protected Area is located between two important ecological areas, Lar national park and the Central Alborz Protected Area, the priority of patches would be changed by a great extent when taking those areas under consideration.