Effect of urban greening and afforestation on soil microarthropod communities in coastal reclaimed land: Insights from functional traits

Urban greening and afforestation are common practices to restore reclaimed land and improve urban environmental quality throughout the World. Soil microarthropods are essential for providing soil ecosystem services and are regarded as valuable indicators of habitat quality, but less attention has been given to their functional responses to restoration in coastal reclaimed land. In this study, we investigated Acari and Collembola communities in four differently restored habitats: unmanaged land, newly afforested land (without soil amendment), urban greenspace (with soil amendment) and old reclaimed afforested land in a reclaimed area of a coastal city in China to assess how taxonomic diversity and functional traits responded to different restoration methods and related soil and vegetation characteristics. We found that urban greening and afforestation significantly increased the taxonomic diversity of Acari but not of Collembola. Significant changes in community composition and functional traits were observed for both taxa. There were generally more large-bodied, well-sclerotized, K-selected, non-phoretic and litter-feeding Acari in the successfully restored habitats. The life form and related traits of Collembola exhibited adaption to different habitats, as unmanaged land and newly afforested land shared similar assemblages; urban greenspaces had the highest proportion of epedaphic Collembola (with developed furca, leg, antenna and ocelli) and algivores/herbivores, while old reclaimed afforested land had the lowest proportion of epedaphic Collembola. Multiple linear regression models revealed that the taxonomic diversity and functional traits of Acari were mainly determined by resource-related factors (soil organic matter and plant diversity), while the functional traits of Collembola were mainly determined by soil water content. Our study demonstrated that functional traits were important in determining the adaption of soil faunal communities to human activities and can be a useful tool for indicating habitat quality and related environmental changes.