Comparison of soil enzyme activity and stoichiometry between urban park and forest in the Pearl River Delta region, China

Urban green spaces are critical in sustainable urban planning, maintaining ecological balance, and enhancing environmental quality and human well-being. However, soil enzyme activity and stoichiometry between urban parks and forests remain poorly understood. Hence, this study was conducted to investigate the role of soil properties, enzyme activities, enzyme stoichiometry (E C:N , E C:P , and E N:P ), vector angle, and vector length by collecting a total of 162 composite soil samples, including two land use types (urban park and forest) across nine cities in the Pearl River Delta region of China. The results revealed that soil water content, organic carbon (SOC), ammonium nitrogen (NH 4 + -N), C:P, N:P ratios, acid phosphatase activity, peroxidase activity, and vector angle in urban parks were significantly lower than in forests. Furthermore, urban parks exhibited higher soil pH, nitrate nitrogen (NO 3 − -N), E C:N , E C:P , E N:P , and vector length than forests. The lower SOC and higher enzyme vector length in urban parks suggested stronger C-limitation than in forests. Meanwhile, vector angle ranged from 52.03° to 61.88° in urban parks and from 54.16° to 65.23° in forests, indicating microbial P-limitation in both soil systems. Structural equation modeling revealed that the soil property was positively correlated with microbial community PLFAs in both soil ecosystems (urban park soil: p < 0.05, forest soil: p < 0.001). Litter C, N, and P contents were negatively linked to VA in urban parks and forests. These findings underscore the potential for tailored management strategies in urban parks, such as selective litter retention and targeted C and P fertilization, to mitigate microbial nutrient limitations, enhance soil fertility and enzymatic functions, and improve urban ecosystem services in the Pearl River Delta region. • Proposing enzyme vector analysis (vector angle/length) as a sensitive indicator of microbial element limitation. • Linking management practices (e.g., litter removal, compaction) to degradative shifts in microbial functions. • Providing actionable strategies for urban planners to optimize green space sustainability in high-density regions.