Landscape-scale impacts of transportation infrastructure on spatial dynamics of two vulnerable ungulate species in Ghamishloo Wildlife Refuge, Iran

摘要

Development of roads through protected areas can have deleterious effects on natural habitats containing species of conservation concern. During the past decades road construction has affected many former remote areas and led to fragmentation and isolation of wildlife populations. The present study focuses on the ecological impacts of Isfahan's West Freeway, which passes through Ghamishloo Wildlife Refuge; an IUCN category IV protected area, in Isfahan Province. The two key affected species, both classified as vulnerable by IUCN, the goitered gazelle {Gazella subgutturosa subgutturosa) and the wild sheep (Ovis orientalis isphahanica) were subject to impact analyses. We used habitat evaluation procedure (HEP) as a habitat-based impact assessment methodology which considers habitat quality and quantity. Habitat quality was measured as habitat suitability index (HSI) for each species. By literature review and field observations, five variables defining habitat suitability were identified and suitability maps for both species generated. Habitat units (HUs) were derived from multiplying the HSI for each species by the habitat area before and after freeway construction. The results showed that due to the construction of the freeway, about 14% of the HUs for goitered gazelle and about 9% of the HUs for wild sheep were lost. In addition, for quantifying landscape pattern change due to freeway construction, various landscape metrics were calculated for the species distribution polygons for two times before and after freeway construction. Results obtained through quantifying landscape metrics showed that mean nearest neighbor (MNN) and number of patches (NP) metrics increased. On the other hand, CONTAG metric decreased in both goitered gazelle and wild sheep distribution polygons, demonstrating the negative effect of freeway on these species distribution polygons integrity. According to the results of this study, mitigation and compensation activities should be considered in Ghamishloo Wildlife Refuge. Our study demonstrated that HEP method combined with quantifying landscape metrics might provide a powerful tool for assessing ecological impact of technical infrastructures on populations of far-ranging species of conservation concern.