Unravelling how urbanization influences soil invertebrate community assembly, food web interactions and associated ecosystem functions

随着全球城市化程度的不断提高，大多数人生活在人们仍然知之甚少的城市生态系统中。城市土壤有不同的来源，受到人类活动的严重干扰和管理，并拥有新颖的植物群落，其中包括城市规划者和园丁选择的非本地物种。这些植物为土壤提供了新的有机物质输入来源，但也经常被从生态系统中移除(例如秋叶凋落物、枯木)，这可能会对土壤生物群产生重要影响。尽管无脊椎动物对有机质分解、土壤结构和养分循环等关键生态系统功能做出了贡献，但人们对城市栖息地类型和管理实践的镶嵌如何影响土壤无脊椎动物群落及其食物网相互作用知之甚少。这项研究计划旨在了解与城市化相关的不同非生物过滤器(如土壤压实、封闭表面或污染物)和生物过滤器(去除落叶、非本地植物物种和微生物群落)如何影响土壤无脊椎动物群落组合、土壤食物网相互作用和相关的生态系统功能。我们是否观察到土壤无脊椎动物消费者及其资源的同质化，或者加拿大城市的城市化梯度保持了功能多样性？城市化是否影响城市土壤食物网中消费者和资源特征的空间协变以及随后的消费者与资源的相互作用？了解优势无脊椎动物的扩散特征、非本地蚯蚓的存在或由于清除落叶而导致的碎片化是否有助于解释这种模式？支持生态系统服务的提供，如凋落物分解期间的养分循环或土壤渗透，是否随着城市化而保持不变？利用实地和实验室的观察、实验和建模方法，以及最先进的工具，如氨基酸的化合物特定稳定同位素分析，我们将探索这些问题。这项研究计划将为促进对土壤食物网的基本了解以及凋落物和土栖无脊椎动物之间的功能相互作用做出新的贡献。此外，它将基于加拿大城市的研究，为城市生态系统管理者和城市开发商提供关键的基线知识，通过考虑土壤生物多样性及其支持的生态系统服务，在城市规划中做出更明智的决策。

With increasing urbanization across the planet, a majority of humans are living in urban ecosystems that are still poorly understood. Urban soils have diverse origins, are heavily disturbed and managed through human activity and host novel plant communities that include nonnative species selected by urban planners and gardeners. These plants provide new sources of organic matter input to soils, but are also often removed from the ecosystem (e.g. autumn leaf litter, dead wood) with potentially important consequences for soil biota. Despite invertebrates contributing to key ecosystem functions such as organic matter decomposition, soil structure and nutrient cycling, little is known about how the mosaic of habitat types and management practices in cities affects soil invertebrate communities and their food web interactions. This research program aims to understand how different abiotic filters (e.g. soil compaction, sealed surfaces or pollutants) and biotic filters (leaf litter removal, nonnative plant species and microbial communities) linked with urbanization influence soil invertebrate community assembly, soil food web interactions and associated ecosystem functions. Do we observe homogenization of soil invertebrate consumers and their resources or is functional diversity maintained across urbanization gradients in Canadian cities? Does urbanization influence the spatial covariation of consumer and resource traits and subsequently consumer-resource interactions in urban soil food webs? Can understanding dispersal traits of dominant invertebrates, the presence of non-native earthworms or fragmentation due to removal of leaf litter help explain such patterns? Is supporting ecosystem service provision such as nutrient cycling during litter decomposition or soil infiltration constant with urbanization? Using observational, experimental and modelling approaches in the field and laboratory, as well as state-of-the-art tools like compound specific stable isotope analysis of amino acids, we will explore these questions. This research program is poised to make novel contributions to advance fundamental understanding of soil food webs and functional interactions among litter and soil-dwelling invertebrates. Additionally, it will provide critical baseline knowledge for urban ecosystem managers and urban developers, based on research in Canadian cities, to make more informed decisions in city planning by considering soil biodiversity and the ecosystem services they support.