Solidago canadensis enhances its invasion by modulating prokaryotic communities in the bulk soil

Several explanations have been proposed for the rapid spread of Solidago canadensis in various environments. Yet, the specific role of soil prokaryotes in this process remains unclear. To understand the prokaryotic role, we conducted a field study in eastern China, where S. canadensis invaded the native plant Humulus scandens. Prokaryotic communities in the soil were studied across three levels of invasion intensity: low, medium, and high (S. canadensis less than 10, about 50, and above 90%, respectively). We found that the S. canadensis invasion decreased the total prokaryotic abundance in the bulk soil (1.61 ± 0.57 × 10⁸ to 5.78 ± 3.65 × 10⁷ copies g⁻¹ DW), but increased the total prokaryotic abundance in S. canadensis (7.72 ± 5.11 × 10⁷ to 1.27 ± 0.71 × 10⁸ copies g⁻¹ DW) and H. scandens rhizosphere (1.11 ± 0.28 × 10⁸ to 1.79 ± 0.68 × 10⁸ copies g⁻¹ DW). S. canadensis invasion enhanced nutrient-releasing microorganisms (Actinobacteria) (p < 0.05) and disease-resistant microorganisms (Nocardioides) (p < 0.05), while decreasing N-cycling microorganisms (Thaumarchaeota and Nitrospirae) (p < 0.05). This study suggests that S. canadensis may enhance its invasion by modulating the species and relative abundance of functional microorganisms in the bulk soil.