Metabolic and Biological Responses of Degraded Black Soils to Poplar Plantation

    Soil micro-food webs are essential in maintaining soil health through individual life activities and intra- and interspecific interactions. However, black soils degradation destabilizes soil micro-food webs and causes loss of soil function. Although vegetation restoration is considered the most effective method for sustainable management of soil health and ecosystems, the existing knowledge on black soils - poplar - microfood web interconnections is still limited. In this experiment, we investigated the effects of Populus simonii × P. nigra (P. xiaohei) on soil biomes in different levels of degraded black soils, in particular amplifying the interactions between four biomes's key taxa and differential metabolites. We characterized soil chemical and enzyme activity properties, community composition of soil biomes, and metabolic profiles. We found that poplar could increase the diversity of four soil biomes in degraded black soils and promote soil micro-food web stability. In addition, P. xiaohei induced consistent changes in high trophic level protists and nematode communities in different degrees of degraded black soils. With deeper degradation, the survival strategy of P. xiaohei shifted from acquisition to conservation, and the driving microorganisms shifted from a resource acquisition strategy to a community with high growth potential. Futhermore, P. xiaohei enhanced soil metabolic processes by driving different trophic-level taxa in the soil micro-food web, and similar metabolites were accumulated to ultimately contribute to soil nutrient cycling. These findings provide insights into how poplar affects changes in soil biological and metabolic characteristics in degraded black soils and are critical for developing specific components of vegetation measures to protect the health of degraded black soils.