Landscape management alters relationships between edaphic conditions, bacterial diversities, and nitrogen-cycling traits

Abstract

Urbanization has dramatic effects on riparian ecosystem functioning. China implemented ecological restoration through the landscape construction of riverside green spaces. Soil microbiome restoration is key to the recovery of riverside ecosystem functioning. However, it remains unknown how restoration strategies affect biodiversity-function relationship. Here we examined bacterial communities and functional profiles using high-throughput sequencing, quantitative polymerase chain reaction in adjacent pairs of landscaped and undeveloped riparian green spaces. We also explored how soil properties, bacterial communities, and functions interact using structural equation modeling. Results showed that the landscaped system had higher soil nutrients and moisture, and more uniform bacterial alpha and beta diversity than the undeveloped system. Landscaped systems harbored more abundant denitrification genes, while undeveloped systems had more abundant nitrification genes. In the landscaped system, bacterial alpha diversity is independent of soil factors and negatively correlated with multiple nitrogen-cycling processes. In resource-limited undeveloped system, bacterial alpha diversity negatively responded to soil nutrients, but positively affected nitrification. Moreover, soil nutrients negatively and positively impacted denitrification and dissimilatory nitrate reduction to ammonium (DNRA), respectively in the undeveloped system. In the landscaped system, high soil moisture promoted denitrification and anammox (anaerobic ammonium oxidation), which contributed to nitrogen loss. Collectively, landscape management influenced bacterial diversity, function, and their relationship by altering soil resource.