Urban biodiversity and carbon sinks – do they overlap? Case study of Helsinki Metropolitan Area, Finland.

Abstract Amongst the greatest global environmental challenges of our time are climate change and biodiversity loss. Feedback mechanisms associated with warming climate could also lead to large-scale biodiversity losses worldwide and it would therefore be logical to seek mitigation methods beneficial for both impact categories. However, research on the topic remains relatively scarce. Our study focuses on two key aspects of environmental sustainability, carbon storage capacity and species biodiversity, to determine whether these correlate at different levels of urban density. GIS-datasets are utilized to estimate the carbon storage potential and species diversity across the urban landscape as well as their association at different levels of urban land use intensity. The results highlight the importance of small green spaces at dense urban cores, indicating that in environments where green infrastructure is limited high species diversity and carbon storage are more likely to overlap, whereas at urban fringe the observed relationship is weaker and divergence of the two impact categories becomes more probable. The study draws attention to the role fragmented, limited green spaces play at establishing functioning ecosystems at local scale and provides new information to support the development of sustainable planning and management practices across the urban land use gradient.