Landscape Ecological Analysis of Green Network in Urban Area Using Circuit Theory and Least-Cost Path

Quantitative securing of green space in already developed cities has many practical limitations due to socio-economic limitations. Currently, South Korea is planning a green network to secure and inject effective green space, but it is difficult to reflect it in the actual space plan due to the abstract plan. This study utilizes circuit theory and least-cost path methods for presenting a green network that is objectified and applicable to spatial planning. First, an analysis of the Least-cost Path revealed 69 least-cost paths between 43 core green areas of the study site. Most least-cost paths have been identified as passing through small green areas and streams in the city. Using the circuit theory, it was also possible to distinguish areas other than least-cost paths from areas with high potential for development, areas where target species are concentrated within corridors. In particular, areas with relatively high green network improvement effects were derived within and around corridors. This study is most significant in establishing and evaluating existing urban green networks, overcoming the limitations discussed at the linear level and expanding to the area level. To increase the utilization of this study in the future, field surveys and monitoring studies on target species need to be supplemented.

Ecological connectivity in fragmented agricultural landscapes and the importance of scattered trees and small patches

Background Fragmentation and habitat loss can restrict species movement and reduce connectivity, negatively impacting biodiversity. Characterising the overall connectivity of an area can inform better management of human modified landscapes. Contemporary connectivity modelling methods seldom incorporate fine-scale movement patterns associated with movement between fine-scaled structural connectivity elements such as scattered trees, roadside corridors and small patches of habitat. This study aims to characterise connectivity within the Karuah-Myall catchments, a typical woodland ecosystem that is fragmented by agriculture, using least-cost path analysis and a graph-theoretic approach; it focuses on how fine-scaled vegetation such as scattered trees support connectivity. We mapped scattered (and paddock) trees within this agricultural landscape where the main human modified land use was pasture. We modelled connectivity for a general representative woodland species using an interpatch dispersal distance and gap crossing threshold, and resistance from different land cover types. The gap crossing distance threshold was used to model movement between fine-scaled vegetation features. We compared the least-cost paths modelled with and without scattered trees. Results Our results show that by excluding scattered trees, least-cost paths across the cleared pasture landscape did not reflect the types of movement patterns typically observed from field studies, such as those associated with a foray-search strategy used by small and medium mammals and birds. The modelling also shows that the Karuah-Myall catchments are well connected and provide value to biodiversity beyond the catchment borders, by connecting coastal vegetation to the Great Eastern Ranges national wildlife corridor initiative. Conclusion Connectivity models that exclude fine-scale landscape features such as scattered trees and small, linear patches risk misrepresenting connectivity patterns. Models of regional-scale connectivity can be influenced by the presence or absence of even the smallest features, such as scattered trees.

Assessing the Impact of Including Traversal across Slope on Least Cost Path Accuracy: A Roman road case study

Despite the methodological issues of Least Cost Path analysis being well known, the inclusion of traversal across slope has not been assessed. This paper uses a Roman road built along a ridge in Cumbria, England as a case study. The ‘High Street’ Roman road provides a suitable case study as its route along the ridge is dictated by the topography. By comparing the computed Least Cost Path results when including and not including traversal across slope as a cost component, this research has found that the inclusion results in Least Cost Paths that more accurately model the known route of the Roman road along the ridge. The Least Cost Path model when not including traversal across slope resulted in 84.8% of the Least Cost Path being within 600m of the known route, compared to 100% when including traversal across slope. Due to the application of anisotropic cost functions, this research also identified that both Least Cost Path models predicted the route from the south towards the north frontiers more accurately, suggesting the Roman road was built with this direction of movement in mind.

Connectivity Study in Northwest Spain: Barriers, Impedances, and Corridors

Functional connectivity between habitats is a fundamental quality for species dispersal and genetic exchange throughout their distribution range. Brown bear populations in Northwest Spain comprise around 200 individuals separated into two sub-populations that are very difficult to connect. We analysed the fragmentation and connectivity for the Ancares-Courel Site of Community Importance (SCI) and its surroundings, including the distribution area for this species within Asturias and in the northwest of Castile and León. The work analysed the territory’s connectivity by using Geographic Information Systems (GIS). The distance-cost method was used to calculate the least-cost paths with Patch Matrix. The Conefor Sensinode software calculated the Integral Connectivity Index and the Connectivity Probability. Locating the least-cost paths made it possible to define areas of favourable connectivity and to identify critical areas, while the results obtained from the connectivity indices led to the discovery of habitat patches that are fundamental for maintaining connectivity within and between different spaces. Three routes turned out to be the main ones connecting the northern (Ancares) and southern (Courel) areas of the SCI. Finally, this work shows the importance of conserving natural habitats and the biology, migration, and genetic exchange of sensitive species.