Spatial variation and relationship between soil dissolved organic matter and bacterial community in urban greenspaces

Large-scale investigations of soil dissolved organic matter (DOM) and the relationship between bacterial diversity and DOM with climatic gradients are important to reveal the influence of climatic factors on soil DOM. The objectives of this study were to (1) investigate the distribution pattern of DOM at a large scale, (2) investigate the effects of climate change on DOM components and microbial communities, and (3) investigate the relationship between microbial communities and DOM components. This study involved the collection of 54 urban greenspaces samples from five climate zones in mainland China and utilization of FT-ICR-MS and 16S rRNA sequencing techniques to reveal the relationship between microbial communities and DOM. Our results showed that the DOM in soil was DOM inated by lignins, followed by proteins, unsaturated hydrocarbons and lipids. Structural equation modeling (SEM) indicated that lignins and proteins shared a negative response pattern with mean annual precipitation (MAP), while lipids and tannins showed a positive correlation with MAP. The differences in bacterial community composition among different climatic zones were not significant, and the DOM inant bacteria in the soil were Proteobacteria, followed by Acidobacteria and Actinobacteria. Bacterial diversity was highest in the subtropical monsoon climate, lowest in the tropical monsoon climate. In addition, SEM indicated that there was a significant correlation between the composition and diversity of DOM and the diversity and abundance of bacteria. Our results provided a deeper understanding of the impact of climatic factors on DOM components and the relationship between bacterial diversity and DOM in urban greenspaces. Graphical Abstract