The Importance of Connected and Interspersed Urban Green and Blue Space for Biodiversity: A Case Study in Cork City, Ireland

Abstract

Urban green and blue space (UGBS) is becoming increasingly important for supporting biodiversity, with the spatial configuration of these landscapes essential to supporting a range of taxa. The role of UGBS for supporting biodiversity is well established, but there remains a lack of consensus on the importance of the overall landscape configuration and the scale at which these configurations are analyzed. Moreover, statistical models are often compounded by coarse representations of UGBS that ignore ‘invisible’ spaces (i.e., gardens and brownfield sites). Using Sentinel-2 satellite data and a maximum likelihood classification, a comprehensive landcover map of Cork City, Ireland was produced with reliable accuracy. FRAGSTATS was then used to capture landscape metrics regarding the spatial configuration of the study area, at a city scale and at three spatial extents for each field site. Field surveys at 72 locations captured data on bird species richness and abundance, before generalized linear models (GLMs) were parameterized between biodiversity metrics and the landscape metrics at 50, 100, and 200 m scales. The UGBS classification revealed that two-thirds of the city is composed of green and blue space. The field surveys recorded 62 species in the city, while GLMs revealed that green space was a significant driver in increasing species richness and abundance, while blue space produced inversions in coefficient estimates, suggesting a more nuanced relationship. The edge effect phenomenon was suggested to play a key role in increasing bird diversity, with a diversified and varied urban landscape important. The impact of scale also affected how blue space was viewed as a connective network within the city, particularly in relation to biodiversity metrics. Overall, this study has demonstrated that UGBS is intrinsically linked to bird diversity. Moreover, 38% of the species recorded are listed as species of conservation concern in Ireland, highlighting how urban spaces can provide habitats for vulnerable species and should inform discussion on the role of geography within the implementation of conservation and planning initiatives for urban environs.