The role of allelopathy and mycorrhizal associations in biological invasions

Traditional approaches to determine allelopathic relationships between plants have focused primarily on the effects that chemicals exuded or leached from one plant species have on competing species. However, when examining the ecological role of allelopathic compounds, research has revealed that phytochemicals produced by exotic species may have a large impact on native plant communities in the invaded range. However, conclusive evidence that biologically active concentrations of allelochemicals accumulate in the soils of invaded sites remains elusive. New research suggests that secretion and movement of high concentrations of allelochemicals through the soil may not be necessary to have a negative impact on native plant communities. It is likely that allelochemicals produced by invading exotic species can disrupt existing ecological associations between rhizosphere microbes and native plant communities, affecting the community structure and diversity. Here we examine the potential role of mycorrhizal-mediated or indirect allelopathy in biological invasions.