Age-associated increase in soil organic matter enhances soil microbial diversity in urban green spaces

Urban green spaces (UGS) are increasingly recognized as a solution to mitigate urban challenges by providing essential ecosystem services, supported by soil microbiomes crucial for biogeochemical processes. Previous studies comparing microbial diversity between UGS and natural ecosystems have shown inconsistent results, potentially due to overlooking the time elapsed since UGS construction, a significant factor influencing soil properties. To investigate this, 30 UGS across Seoul, South Korea were selected based on their age, along with 7 natural ecosystem sites outside Seoul for comparison. The study focused on exploring the relationship between UGS age and changes in soil chemical and microbial properties. The findings reveal a notable correlation between the elapsed time since UGS construction and various soil characteristics, including chemical properties, microbial community structure, diversity, and functional properties. As UGS mature, these properties gradually resemble those found in natural ecosystems, which was further confirmed through global meta-analysis. This indicates that as UGS age, soil chemical properties, especially soil organic matter, increase, thereby enhancing microbial diversity and shifting functional profiles to align more closely with natural ecosystems. This insight implies that current UGS management practices positively influence soil health and ecosystem functions. This study not only enhances our understanding of soil microbial ecology in UGS but also offers valuable guidance for managing UGS to promote sustainable urban ecosystems.