Is urban park a carbon sink or source? A study based on an annual evaluation framework

Abstract

Background Urban parks play a critical role in both carbon reduction and sequestration, thereby contributing to the carbon balance in the urban carbon cycle. However, while these parks provide valuable recreational services, they also generate significant carbon emissions. This study aims to evaluate whether urban parks can effectively serve as carbon sequestrations. By establishing a carbon balance evaluation framework, we assessed the annual carbon balance of 15 urban parks in Nanjing, China, and identified significant landscape indicators influencing this balance. Results The case-study results from Nanjing, China, indicate that under the context of regional carbon intensity, the annual carbon balance of the 15 parks exhibits significant variability. Eight urban parks serve as carbon sinks and seven as carbon sources. Larger parks with higher vegetation coverage demonstrated greater carbon sequestration capacity. Moreover, green waste and building operations and management were the primary sources of carbon emissions. The green space ratio, tree canopy area, shoreline length, lawn area and water surface ratio were closely linked to achieving a carbon balance. Conclusions This study is significant because it advances urban carbon balance goals, provides data support for the renewal and transformation of urban parks, and offers valuable insights for optimizing management practices.