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Urbanization negatively impacts aboveground biodiversity, such as bird and insect communities. City parks can reduce these negative impacts by providing important habitat. However, it remains poorly understood how the degree of urbanization and vegetation types within city parks (e.g., lawns, woodland) impact soil biodiversity. Here we investigated the impact of the degree of urbanization (urban vs. suburban) and vegetation type (lawn, shrub-lawn, tree-lawn and tree-shrub mixtures) on soil biodiversity in parkland systems. We used eDNA metabarcoding to characterize soil biodiversity of bacteria, fungi, protists, nematodes, meso- and macrofauna across park vegetation types in urban and suburban regions in Xiamen, China. We observed a strong effect of the degree of urbanization on the richness of different soil biota groups, with higher species richness of protists and meso/macrofauna in urban compared to suburban areas, while the richness of bacteria and fungi did not differ, and the difference of nematode richness depended on vegetation type. At the functional level, increased degree of urbanization associated with greater species richness of bacterivores, plant pathogens and animal parasites. These urbanization effects were at least partly modulated by higher soil phosphorous levels in urban compared to suburban sites. Also, the vegetation type impacted soil biodiversity, particularly fungal richness, with the richness of pathogenic and saprotrophic fungi increasing from lawn to tree-shrub mixtures. Tree-shrub mixtures also had the highest connectedness between biotas and lowest variation in the soil community structure. Overall, we show that soil biodiversity is strongly linked to the degree of urbanization, with overall richness increasing with urbanization, especially in bacterivores, plant pathogens and animal parasites. Targeted management of vegetation types in urban areas should provide a useful way to help mitigate the negative effect of urbanization on soil biodiversity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Urbanization is threatening terrestrial biodiversity and ecosystem functions. Nematodes, as one of the most abundant animals on Earth, play diverse roles within soil food webs and contribute to vital ecosystem services. However, the effects of urbanization on soil nematode functional groups, and the ecological functions and services they provide remain poorly understood. Here, we investigated functional groups of soil nematodes across 12 cities in China and validated the results by using a global nematode dataset. Specifically, we found the proportions of omnivores (by 45∼60%) and predators (by 40∼50%) as well as temporal ecosystem stability (by 10∼20%), as indicated by the normalized difference vegetation index, were reduced in urban ecosystems, while the proportions of fungivores and bacterivores increased (30–60% and 10–20%, respectively). We identified total soil phosphorus and nitrogen as the main drivers influencing soil nematode feeding groups in urban ecosystems. Soil pH, mean annual precipitation, and mean annual temperature were predominant factors in non-urban ecosystems. We further demonstrated that nematode functional guilds contributed to ecosystem stability in urban ecosystems, but this was not true in non-urban ecosystems. Our findings evidence the homogenization effects of urbanization on key functional guilds of soil nematodes and their roles in maintaining ecosystem stability. The fact that ecosystem stability and the abundance of nematode functional guilds are closely related and driven by climatic, edaphic, and anthropogenic factors may help in setting priorities for urban soil management. • Temporal stability was reduced in urban soils. • Omnivores and predators were decreased in urban soils. • Total soil phosphorus and nitrogen were the main drivers of urban nematodes. • Soil nematodes contributed to ecosystem stability in urban ecosystems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Community and functional traits of Collembola in suburban and urban greenspaces. • An increase in soil pH and phosphorus caused by urbanization favored soil microbial communities. • Bacteria and fungi correlated with the taxonomical and functional structure of Collembola, respectively. • Collembola communities and functional traits were homogenized in urban greenspaces. • Collembola richness was (in-)directly inhibited by urbanization and greenspace type. Urban regions are rapidly expanding worldwide resulting in biotic homogenization and loss of ecological functions in urban ecosystems due to management practices targeting at satisfying aesthetic and health demands of urban residents. These practices also modify living conditions and food recourses of soil invertebrates thereby affecting the structure and functional diversity of soil animal communities including collembolans. Here, we assessed the response of the community composition and functional diversity of collembolans as a major component of soil food webs to urbanization (suburban vs urban region) and greenspace types (including forest and four park-associated greenspaces: lawn, lawn with shrubs, lawn with trees, and lawn with shrubs and trees). Our results highlight that both urbanization and greenspace type significantly affect soil properties and community structure of collembolans. The negative effect of urbanization and park-associated greenspaces on species and functional composition of collembolan communities were likely due to both changes in soil abiotic conditions and bacterial community composition, whereas the reduction of collembolan functional traits likely resulted from changes in soil abiotic conditions and fungal community composition. In park-associated greenspaces richness and diversity of bacterial communities were highest in lawns with trees and lowest in forests. By contrast, species richness and diversity of fungal communities were highest in lawns with shrubs, but, similar to bacteria, lowest in forests. Community composition and functional traits of collembolans were more homogeneous in urban than suburban greenspaces pointing to reduced functioning of collembolan assemblages in urban areas. Overall, our results suggest that changes in soil properties and bacterial communities caused by urbanization and greenspace type are important factors contributing to taxonomic homogenization of collembolan communities, while the loss of functional traits of collembolan communities in urban greenspaces is likely caused by changes in soil properties and fungal community composition. [ABSTRACT FROM AUTHOR]

Urbanization-induced environmental changes such as habitat fragmentation impact arthropod assemblages and food web-related ecosystem functions, such as nutrient cycling and energy fluxes. Yet, we lack insight into how arthropod food webs are structured along urban fragmentation gradients. Here, we investigated the community composition and food web structure of litter-dwelling arthropods along fragmentation gradients (green median strip, i.e. green fragments in the middle of roads, urban park, urban forest and natural forest) in Xiamen City, southeast China. We found the density of litter-dwelling arthropods in median strips and urban parks to be two to four times higher than in urban and natural forests, with, as indicated by literature-based stable isotope values, 67%–68% of the individuals comprising primary consumers (trophic level I). Consequently, more complex food webs were found in small urban fragments (i.e., green median strip and urban park) than in the other fragments studied, including higher linkage density and higher energy flux. The biomass of litter on the floor was significantly correlated with the density of arthropods of trophic levels I, III and IV, and each trophic guild positively correlated with each other pointing to the dominance of bottom-up forces. Overall, our results suggest that small urban fragments maintain a high density of arthropods forming complex food webs and thereby may contribute to maintaining high energy fluxes and providing important ecosystem functions in urban areas. [Display omitted] • Structural changes in arthropodan food web along urban fragment size, using fluxweb package. • Food webs of litter-dwelling arthropods in urban fragments were complex and structured. • Small fragments had more complex food web structures than natural forest. • Urban forest had the simplest food web structure, but presented as urban biodiversity hotspot. • The density of adjacent trophic levels correlated positively indicating bottom-up control. [ABSTRACT FROM AUTHOR]