Plant–soil feedbacks can exacerbate com- petition between invasive and native species, although the net effect of the interaction between soil biota and competition is likely to be species-specific. Very few studies have addressed the combined effect of soil and competition on plant performance and invasion by exotic woody species. This study explores plant growth and competition between Acacia dealbata and Pinus pinaster in three different soils—native, disturbed and invaded—in Portugal. The invasion of native P. pinaster forests by A. dealbata can be explained by the stronger competition ability of the exotic tree species. Competition is stronger in the native soil, allowing the establishment of A. dealbata in this soil and the displacementof P. pinaster. Duringinvasion, A. dealbata changes soil conditions and establishes positive plant–soil feedbacks that promote its own germination and growth and increase P. pinaster mortality. Soil disturbance by the introduction of a different exotic species, Eucalyptus globulus, did not promote invasion by A. dealbata. We found a signif- icant effect of soil legacy on both growth and compet- itive ability of the invasive A. dealbata. The ability of A. dealbata to outcompete the native P. pinaster in its own soil and the positive plant–soil feedbacks estab- lished after invasion are important mechanisms for A. dealbata invasion.
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