Abstract
Abstract
Human modification of the landscape leads to habitat loss and fragmentation. The ability of remnant habitat to host viable populations of certain wildlife species may depend on patch size and connectivity in these fragmented landscapes. Habitat fragmentation leads to disconnection between subpopulations, and connectivity between patches is necessary to mitigate the negative effects of fragmentation. Corridors ensures connectivity between habitat patches and facilitates species migration and dispersal between suitable habitats. Maximum entropy Species Distribution Modeling is a useful method to gain insight into where there is suitable habitat for different species of wildlife using presence-only to predict probability of presence of a species. Circuit theory derived from electrical engineering has been adapted for use in ecology to model organisms movement in the landscape. Circuit theory is a conceptual framework that treats landscapes as conductive surfaces through which organisms move like currents in an electrical circuit and helps understand how landscape features influence movement. This thesis explores how available different types of green spaces affect habitat suitability and how different type of green spaces affect urban connectivity. To achieve this, I employed Maxent and Circuitscape software to analyze 82 species of terrestrial vertebrate species with data collected by citizen science in Trondheim municipality. Species were grouped together for simplicity. I added layers of different urban green spaces and distance to city boundary and conducted analyses with generalized linear models and linear models on habitat suitability and connectivity. My research revealed that being inside a green area had a positive effect on habitat suitability and connectivity for most species groups, with the exception of amphibians and upland birds. Habitat suitability and connectivity decreased with an increased distance to boundary for most groups, but this effect was often non-linear, suggesting that habitat suitability and connectivity varied with distance to boundary. Connectivity was strongly associated with aquatic landscape features, indicating that blue-green corridors had a significant impact on urban connectivity. R2 values were low for all species groups and single species, suggesting that the predictors used in this study did not satisfactorily explain urban connectivity. Since citizen science data were not collected using a standardized method, this may have biased the results of this study. However, Maxent and Circuitscape software are useful tools to assess habitat suitability and connectivity both inside and outside urban environments.
