Increased fine roots, exudates and altered rhizospheric functions in the invasive plant Sphagneticola trilobata compared to the native Sphagneticola calendulacea

The invasion of exotic plants has a significant impact on terrestrial ecosystems, while the underlying mechanisms are diverse and sometimes contradictory. A systematic study on root morphology and functions in the rhizosphere would shed light on a convincing invasion mechanism and practical control measures. We conducted a greenhouse experiment with the invasive Sphagneticola trilobata and the native Sphagneticola calendulacea to and systematically investigated their root morphology and rhizospheric functions. The growth, photosynthesis, root morphology and exudates, as well as the microorganisms in the rhizosphere were measured. The invasive S. trilobata not only grew faster and better, but also had a higher organic acid content in the root exudate than the native S. calendulacea, although their exudate chemical properties were similar. The invasive S. trilobata also had a greater amount of fine roots and a higher SRL than the native S. calendulacea, allowing for more root exudates to support the growth and reproduction of soil microbes, which in turn regulate the plant's nutrient uptake. We also found that S. trilobata alters the microbial composition of the soil, and influenced the β-diversity of fungi. These coordinated responses could promote the growth performance of S. trilobata and facilitate its invasion. Our results provide a framework for the mechanisms of plant invasion from the perspective of ecological processes in the subsurface rhizosphere.