Plant-Soil Interactions of an Invasive Plant Species in its Native Range Help to Explain its Invasion Success Elsewhere

Abstract

Abstract Purpose: To compare plant-soil feedback (PSF) of invasive Cirsium vulgare and non-invasive C. oleraceum in their native range to test a hypothesis that the invasive species is more limited by specialized pathogens in the native range and/or able to benefit more from generalist mutualists, and thus may benefit more from loss of specialized soil biota in a secondary range.Methods: We assessed changes in soil nutrients and biota following soil conditioning by each species and compared performance of plants grown in self-conditioned and control soil, from which all, some or no biota was excluded. Results: The invasive species depleted more nutrients than the non-invasive species and coped better with altered nutrient levels. The invasive species had higher seedling emergence which benefited from presence of non-specific microbes. The invasive species biomass responded less positively to specialized (self-conditioned) microbiota and more negatively to specialized larger-sized biota compared to the non-specialized control biota, suggesting the species may benefit more from enemy release and suffer less from loss of specialized mutualists when introduced to a secondary range. The invasive species showed greater ability to decrease its root-shoot ratio in presence of harmful biota and thus reduce their negative effects on its performance.Conclusions: Our study highlights the utility of detailed PSF research in the native range of species for understanding the factors that regulate performance of invasive and non-invasive species in their native range, and for pinpointing the types of biota involved in their regulation and how this changes across the plants life cycle.