Analysing carbon density in urban parks by considering the management of different functional parks: A case study in Beijing

Abstract

Urban parks are a major component of urban green spaces and are reserved for recreation, aesthetics and cultural heritage. With increasing attention to carbon neutrality in China, urban parks play an important role in carbon sequestration. This new expectation requires us to examine the impacts of current design and management in urban parks on carbon density. This study took Beijing as an example and investigated a total of 9 parks within 4 functional categories, i.e., landscape parks with small, medium, and large sizes and natural forests. As parks worked for various functions, their plants species and tree sizes were distinct. Big trees were scattered in small parks; while big parks had natural-like landscape with ample medium- and small-sized trees. We analysed their aboveground and belowground carbon density, as well as associated variables, such as biodiversity, soil bulk density, nitrogen (N) content, etc. Soil types were the same for different parks, but managements leaded to different soil properties. Medium- and large-sized landscape parks had the highest aboveground carbon density (60.86 t·hm−2 and 79.18 t·hm−2, respectively), which was higher than that of natural forests (43.20 t·hm−2), while small-sized landscape parks had the highest belowground carbon density (185.22 t·hm−2), which was slightly less than that of natural forests (207.17 t·hm−2). The high aboveground carbon density in landscape parks with medium and large sizes was attributed to the well-planted trees and high biodiversity, especially for the high ratio of brush (62.12 %). High belowground carbon density in small landscape parks resulted from careful management, such as timely fertilization and frequent soil loosening, which led to high organic matter and low bulk density (1.1206 kg·cm−3), promoting soil carbon sequestration. We therefore provide specific advice in managing different parks in regard to their carbon density, expecting to increase carbon density in urban parks by an average of 224 %.

Keywords

• Green space
• Park scale
• Carbon density
• City planning
• Park management