# Urban forest plant diversity affects soil organic carbon by regulating functional genes in Nanning

## TL;DR

Urban forests with higher plant diversity in city centers help regulate soil carbon through specific microbial genes.

## Contribution

Identifies specific functional genes (K15635 and K01965) linked to soil carbon regulation in urban forests.

## Key findings

- Urban centers showed higher plant diversity and active soil organic carbon fractions.
- Microbial functional genes, not diversity, regulate soil carbon sequestration in urban forests.
- Plant diversity influences active, but not stable, soil organic carbon fractions.

## Abstract

Urban forests serve as reservoirs of soil organic carbon (SOC) within ecosystems and play a critical role in the carbon (C) cycle. However, the regulatory mechanisms underlying SOC dynamics across urbanization gradients in urban forests remain poorly understood. In this study, we investigated the interrelationships among plant diversity, SOC and its oxidation-stable fractions, and functional genes across an urbanization gradient encompassing an urban center (UC), subcenter, suburb, and exurb. Our findings revealed that urbanization significantly enhanced plant diversity and altered SOC dynamics. UC exhibited higher plant diversity and increased concentrations of active SOC fractions. Although urbanization did not significantly affect microbial α-diversity, it selectively enriched the relative abundance of specific taxa. C sequestration-related functional genes, particularly K15635 and K01965, were strongly associated with the regulation of SOC dynamics in the urban forest. Our findings underscore the importance of conserving diverse tree communities to enhance the C-sequestration function of urban forests.

•Plant diversity was higher in urban centers than in exurban areas•Urbanization did not significantly affect microbial diversity or community composition•Microbial functional genes regulate soil organic carbon sequestration in urban forests•Urban plant diversity influences active, but not stable, soil organic carbon fractions

Plant diversity was higher in urban centers than in exurban areas

Urbanization did not significantly affect microbial diversity or community composition

Microbial functional genes regulate soil organic carbon sequestration in urban forests

Urban plant diversity influences active, but not stable, soil organic carbon fractions

Natural sciences; Environmental science; Ecology; Plant ecology; Soil ecology