The establishment and productivity of new forestry plantations can be significantly impacted by the presence of native vegetation. In a study site in New South Wales, Australia, the growth of a Pinus radiata plantation has been virtually halted in areas dominated by the native shrub Allocasuarina nana, effects that persist even after its physical removal. We undertook a series of analyses and manipulative experiments to determine the mechanism by which A. nana impedes P. radiata growth. We compared the fungal soil community and metabolomic profile of soils in regions rich in A. nana with adjacent healthy P. radiata areas and the transition zone between them. This data was complemented by a pot experiment to assess P. radiata growth in the different soil types with and without a viable microbial soil community or the addition of A. nana roots or exudates. In my talk, I will discuss the apparent mechanisms by which A. nana appears to be manipulating soil microbial communities and soil parameters to favour its dominance over P. radiata.