Abstract
Soil microbes are of great significance to driving the biogeochemical cycles and are affected by multiple factors, including urbanization. However, the response of soil microbes to urbanization remains unclear. Therefore, we designed an urban-to-rural gradient experiment to investigate the response of soil microbial composition and diversity to urbanization. Here, we used a high-throughput sequencing method to analyze the biotic and abiotic effects on soil microbial composition and diversity along the urban-to-rural gradient. Our results showed that soil bacterial diversity was the highest in urban areas, followed by suburban areas, and was the lowest in exurbs; however, fungal diversity did not vary significantly among the three areas. Plant traits, i.e., tree richness, shrub richness, the number of tree stems, diameter at breast height of trees, and soil properties, i.e., pH, soil organic carbon, soil exchangeable calcium and magnesium, and soil water content, were only significantly influenced bacterial diversity, but not fungal diversity. The effect of trees and shrubs was higher than that of herbs on microbial composition. Soil organic carbon, pH, soil available nitrogen, soil exchangeable calcium, and magnesium were the major soil factors influencing the soil bacterial and fungal composition. Soil properties had a greater influence on bacterial than on fungal composition at genus level, while plant traits contributed more to fungal than to bacterial composition at genus level. Our study suggests that the urban-to-rural gradient affect the composition and diversity of bacterial community as well as the fungal composition, but not the fungal diversity.
Highlights
Acceleration of urbanization globally has led to an explosive increase in global urban population.In 2018, the global urban population of 4.2 billion accounted for 55% of the total population worldwide [1]
tree richness (TR), shrub richness (SR), and tree stems (TS) significantly increased along the urban-to-rural gradient (p < 0.01), whereas herb richness (HR) and diameter at breast height of trees (DBH) showed the opposite trend
We found that TR and SR had a greater impact on soil bacterial and fungal composition, whereas
Summary
Acceleration of urbanization globally has led to an explosive increase in global urban population.In 2018, the global urban population of 4.2 billion accounted for 55% of the total population worldwide [1]. Urbanization has resulted in a series of ecological challenges, such as urban heat islands [2], increased atmospheric CO2 concentration [3], nitrogen deposition [4], and decreased biodiversity [5]. Urban forests are associated with multiple ecological benefits such as absorption of carbon and release of oxygen, regulation of urban microclimate, and diminishing heat island effect, alleviating the impacts of urbanization [6]. As an essential component of urban forest ecosystem, soil microbes participate in many ecological processes and play an important role in urban forest ecosystem. Soil microbes drive biogeochemical cycles [7], via litter decomposition [8,9], catalyzing the turnover of soil carbon and nutrients [10] and alleviation of changes induced by urbanization.
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