Seasonal variation of soil organic carbon stocks and sequestration rates in the CU Centenary Park

Abstract

Urban areas are major contributors of CO₂ emissions, but at the same time greenspace in urban parks can offset CO₂ from the atmosphere and store carbon in vegetation and soils. The CU Centenary Park is designed to serve multi-functional purposes from an ecological aspect to human well-being. However, knowledge on the capacity of soils to store carbon that link to effects from seasonal variation, vegetation covers, and environmental factors is limited. Twenty seven soil samples were collected (0-15 cm) and were divided equally within three land cover types: tree, grass, and shrub. The sampling collection was conducted in September 2019 (represented the wet season) and December 2019 (represented the dry season). Soil organic carbon content was measured by the TOC analyzer. Soil temperature, soil moisture, pH, and bulk density were analyzed using standard methods. Between the dry and wet seasons, there was no difference of SOC stocks. Shrub soils dominantly expressed high SOC stocks over grass and tree (p-value < 0.001). While soil temperature and bulk density did not show statistically significance in the multiple linear regression model (p-value > 0.05), soil moisture was significantly positively influenced on SOC storage (p-value < 0.001) and can be a predictor for estimating SOC stocks. To offset more CO₂ from the atmosphere, the results suggested the proper vegetation planning and irrigation system to be placed in the park.