Dataset on the Effects of Trampling Disturbance on Soil Organic Carbon Fractions in Urban Park Green Spaces

This study categorized sampling sites into three distinct levels of trampling intensity, determined by the percentage difference in soil bulk density between disturbed and undisturbed control (CK) plots, utilizing the Jenks Natural Breaks method: (1) Heavy Trampling (HT) ; (2) Moderate Trampling (MT) ; and (3) Light Trampling (LT) .1 Soil Aggregate FractionationSubsequent to air-drying, soil aggregates were fractionated utilizing a wet sieving technique. Specifically, 50 g of undisturbed air-dried soil was positioned on the uppermost sieve (2 mm diameter) of a nested sieve assembly within a soil aggregate analyzer. The sieves were submerged in water with a controlled water level to ensure sample saturation, followed by a 10-minute pre-wetting period. Mechanical oscillation was then conducted at an amplitude of 3.8 cm and a frequency of 30 oscillations per minute for a duration of 10 minutes. This procedure effectively separated the aggregates into four distinct size fractions: >2 mm, 2-0.25 mm, 0.25-0.053 mm, and <0.053 mm. Each fraction was subsequently oven-dried at 50°C and weighed to determine the mass percentage distribution(Han et al., 2024). For analytical purposes, we operationally defined the fractions as follows: >2 mm as macro-aggregates, 2–0.25 mm as medium-aggregates, 0.25–0.053 mm as small aggregates, and <0.053 mm as micro-aggregates. Determination of Soil Organic Carbon Content: soil organic carbon (SOC) content was determined using the potassium dichromate oxidation-external heating method for both oven-dried (105°C) bulk soil samples and the four aggregate fractions (>2 mm, 2-0.25 mm, 0.25-0.053 mm, and <0.053 mm) obtained through wet sieving. All samples were finely ground to pass through a 0.25 mm sieve prior to analysis.2 Acid-hydrolyzable Organic CarbonThe labile organic carbon fraction (LOC), recalcitrant organic carbon fraction (ROC), and inert organic carbon fraction (IOC) were determined using a two-step acid hydrolysis method.The formulas for calculating the Carbon Management Index (CMI) from soil organic carbon fractions are as follows:Soil Carbon Pool Activity (SCPA) = Labile organic carbon content / (Recalcitrant organic carbon content + Inert organic carbon content) (4)Carbon Pool Index (CPI) = Treated soil organic carbon content / Control soil organic carbon content (5)Carbon Pool Activity Index (CPAI) = Treated soil carbon pool activity / Control soil carbon pool activity (6)Carbon Management Index (CMI) = CPI×CPAI× 100 (7)3 Microbial Biomass Carbon (MBC)Determined using the chloroform fumigation-extraction method.