Effects of multi-scale structure of blue-green space on urban forest carbon density: Beijing, China case study

Landscape structure influences the amount of carbon that can be stored in an ecosystem. Currently, majority of research have been focused on the responses of landscape structure and functional relationships to urbanization, and few have specifically focused on blue-green space. In this study, Beijing was used as a case study to explore the relationship among the blue-green spatial planning structure of green belts, green wedges and green ways, the landscape configuration of bluegreen element and carbon storage of urban forest. The blue-green elements were classified using high-resolution remote sensing images (0.8 m) and the above-ground carbon storage estimations of urban forest based on 1307 field survey samples. The results show that green belts and green wedges have a higher coverage percentage of blue-green space and big blue-green patches than that of built-up areas. However, they have lower carbon density in urban forests. The shannon's diversity index of blue-green space was found to have a binary relationship with carbon density, in which, urban forests and water bodies were the key combination in increasing carbon density. The presence of water bodies in urban forests increases the carbon density to up to 1000 m. The effect of farmland and grassland on carbon density was found to be uncertain. With this, this study provides basis for sustainable planning and management of blue-green spaces.