Using remote-sensing and citizen-science data to assess urban biodiversity for sustainable cityscapes: the case study of Athens, Greece

Context Urban biodiversity is an important and growing research area as cities continue to expand and human populations concentrate in urban centers. In order to effectively conserve urban biodiversity and inform future urban planning, a thorough understanding of the patterns and underlying factors affecting biodiversity is essential. However, a methodology of assessing urban biodiversity that would be replicable to different cities has been challenging, primarily due to data limitation on habitats and species in urban areas. Objectives In response to these challenges, this work implements a biodiversity analysis framework, adapted for the municipality of Athens, Greece, a city that is facing its own unique challenges in preserving biodiversity while accommodating urban growth. The analysis granularity is at the zipcode level. Methods A k-means clustering scheme that leads to theclassification of urban habitats is incorporated using earth observation data, while citizen science-generated species occurrence data from the Global Biodiversity Information Facility (GBIF) platform is used for biodiversity analysis and validation. This integrative approach allows us to account for fine-scale environmental variation, which plays a crucial role in species' abundances and distributions in urban settings. Results Our analysis shows that the fact that almost 80% of the Athens land cover is impervious and lacks vegetation has serious effects on biodiversity in the city, which is very limited and is only abundant in Urban Green areas. The city’s dense urban fabric, followed by intense cementification, lack of open streams and noisy large arterial roads take a toll on urban species occurrences, which are up to 100 times less than the green and blue areas. Conclusions This work highlights the significance of zipcode-level analyses in understanding the complex interplay between urbanization and biodiversity. Furthermore, it shows that it is possible to assess urban biodiversity using free and open satellite data, without previously acquiring a high-resolution species occurrence dataset through field surveys, thus providing a comprehensive understanding of urban biodiversity patterns in cities like Athens.