Fertile islands lead to more conspicuous spatial heterogeneity of bacteria than soil physicochemical properties in a desert ecosystem

Abstract

The “fertile islands” resulting from discrete plants are important for the structure and function of dryland ecosystems. To understand the spatial heterogeneity of soil biotic and abiotic resources as a result of fertile islands in deserts, soil bacterial and physicochemical profiles were measured at four soil depths (0–10 cm, 10–20 cm, 20–40 cm, and 40–60 cm) in three soil patches (under mid-canopies, at the edge of canopy cover, and in bare soil) around legumes (Hedysarum scoparium shrubs) and non-legumes (Artemisia ordosica shrubs). Unexpectedly, the patches of the two plants showed similar soil abiotic and biotic patterns. Copiotrophs and potential decomposers were enriched under mid-canopies, with more phylogenetically clustered bacterial communities, and co-occurrence networks with lower connectivity and higher modularity than in bare soil. In bare soil, oligotrophs and potential nitrate reducers were enriched. Soil properties showed less conspicuous spatial heterogeneity than bacterial communities. The only soil physicochemical properties enriched under mid-canopies were soil organic matter, dissolved organic carbon, and nitrate; their enrichment was significantly related to bacterial communities. This study elucidates the spatial patterns of soil properties and their relationships, which are observed in fertile islands of desert ecosystems, and provides further insights into the mechanisms of soil nutrient redistribution.