The restoration of urban sealed soils is a major stake for urban planners. In particular, characterizing their resilience from a biotic perspective is of primary importance for remobilizing these artificialized substrates in urban green spaces. Using Marseille (France) as a case study, we implemented a metabarcoding next generation sequencing approach to characterize the diversity and the composition of ectomycorrhizal (EM) fungal communities present in soils sealed for 60 years. Based on an inoculation experiment, we tested the ability of the remaining spore bank to establish EM interactions with plants. Altogether, we aimed at assessing the potential of -urban natural habitats to provide an efficient soil EM inoculum for the restoration of urban soils. We found that: (i) long-term sealing drastically reduced the diversity of EM fungi in urban soils, (ii) long-leaved spores of hypogeous gastroid fungi were efficient to establish EM symbioses with plants, and (iii) the efficiency of EM fungal inoculation depended on the natural habitat used as an inoculum source. Oak forests provided species-rich but poorly efficient inoculum. Contrastingly, soils collected in disturbed shrublands (garrigues) hosted moderately-rich EM communities containing droughtadapted species with high ability to colonize urban soils. Our findings highlight that -urban landscapes are promising candidates to feed local systems of urban soil restoration. In this perspective, poorly-considered habitats such as shrublands can be considered as valuable sources of soil biota to prevent the over-exploitation of agricultural areas.

中文翻译：

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城市土壤密封后的寿命：外生菌根接种的弹性和效率的实验证据


城市密封土壤的恢复是城市规划者的主要关注点。特别是，从生物角度表征它们的恢复能力对于在城市绿色空间中重新利用这些人造基质至关重要。以马赛（法国）为案例研究，我们实施了元条形码下一代测序方法来表征密封 60 年土壤中存在的外生菌根 (EM) 真菌群落的多样性和组成。基于接种实验，我们测试了剩余孢子库与植物建立电磁相互作用的能力。总之，我们的目的是评估城市自然栖息地的潜力，为城市土壤的恢复提供有效的土壤微生物接种物。我们发现：（i）长期封闭大大降低了城市土壤中 EM 真菌的多样性，（ii）地下胃真菌的长叶孢子能够有效地与植物建立 EM 共生关系，以及（iii）EM 的效率真菌接种取决于用作接种源的自然栖息地。橡树林提供了物种丰富但效率较低的接种物。相比之下，在受干扰的灌木丛（灌木丛）中收集的土壤中存在中等丰富的 EM 群落，其中包含适应干旱的物种，这些物种具有在城市土壤中定居的高能力。我们的研究结果强调，城市景观是为当地城市土壤修复系统提供支持的有希望的候选者。从这个角度来看，灌木丛等未考虑到的栖息地可以被视为土壤生物群的宝贵来源，以防止农业区的过度开发。