Estimating soil respiration rates between wet and dry seasons in an urban park of Thailand

Abstract

Soil respiration (Rs) is considered the largest component in the terrestrial-atmospheric carbon exchange system. While soils offset organic carbon from the atmosphere, Rs can be a significant source of CO₂ emission. In urban areas where the balance of carbon sink and source is still under debate whether which one is dominant. To understand the dynamics of the amount of urban carbon, in particular a green space, is the key linking to climate change issue. This research investigated Rs rates between the wet and dry seasons, and further analyzed the relationships between Rs rates and environmental covariates i.e. (soil temperature, soil moisture content, soil organic carbon and vegetation cover types). The measurement of Rs rates were conducted in twenty-seven soil samples around trees, grass and shrubs in the CU Centenary Park using a close chamber technique. The difference between average Rs rates in the wet season (1.70±0.41 g CO₂ m⁻² hr⁻¹) and dry season (1.29±0.34 g CO₂ m⁻² hr⁻¹) was found to be statistically significant (p-value < 0.0001). The linear regression model showed no statistically significance of relationship between Rs rates and environmental covariates in both seasons. However, higher mean Rs rate in the area covered by grass was determined when compared to the Rs rates covered by trees. The results indicated that low organic matter input from litterfall management and soil temperature around trees could affect the decomposition process and microorganism activity in the soil.