Assessment of ecological connectivity for urban environments: A multispecies approach
Creators: name: Poodat, Fatemeh
Publisher: name: RMIT University
Year: 2024

description: The habitats of many ground-based fauna species in developing urban regions have altered in their structure and are often isolated from other habitat locations due to the urban growth. Habitat areas that are well connected to other fragments of habitat have been shown to assist particular fauna in their movement from one location to another. Two key benefits of faunal movement are the transfer of genes resulting in improved genetic diversity and support for larger populations of particular species. Habitat connectivity is therefore seen as critical to the survival of many fauna species in urban locations. Lack of habitat connectivity in the landscape poses the critical threat of extinction to many ground-based species. This thesis develops a multispecies method for assessing habitat connectivity in urban landscapes. While effective conservation management requires a multispecies approach to establishing conservation priorities, connectivity is in fact a species-specific attribute of the landscape. This study aims to assess connectivity by developing a multispecies method based on species-specific considerations, thereby addressing the differences in the two aspects. The application of graph theory is well suited to modelling the structure of urban landscapes. A graph-based multispecies method was designed based on specific criteria relating to a biologically realistic assessment of connectivity. This was then applied to Metropolitan Melbourne by determining the habitat networks of four ground-based fauna species and assessing connectivity across species networks. The method was then evaluated by testing the sensitivity of modelling outputs to the determination of the maximum effective distance for the target species and the resistance values that were used to quantify the species resistance layers. The species-specific connectivity outcomes were then overlaid and combined in order to assess overall ecological connectivity. The revised method comprises four key steps. These are: (1) choice of target species for a given urban region; (2) construction of species-specific networks within that region; (3) connectivity measurement of species-specific networks; and (4) combination of connectivity results to assess the ecological connectivity for the urban region. In general, this study offers three innovations. First, the graph-based multispecies method is innovative in terms of multispecies capacity to consider species-specific characteristics when assessing connectivity. Second, it establishes a rigorous set of graph-based metrics that determine essential dimensions of connectivity: connectivity between two specific habitats, connectivity of the whole network, and those habitats that contribute most to connectivity. Third, the study developed a new algorithm for the identification of gaps in species habitat networks. In addition, the method offers new insights into the development of species-specific resistance layers. The multispecies method allows for flexibility in decision-making by providing opportunities for trade-offs between different conservation alternatives. The method will serve as a foundation to support conservation planning and decision-making through the establishment of priority areas within the urban landscape that will enhance connectivity and support biodiversity. This multispecies method will assist any conservation authority to avoid redundancy in planning and decision-making, thereby ensuring long-term financial savings in conservation projects. <br>