Accounting for soil microbial communities during ecological restoration

Invasive plants often negatively impact the (a)biotic conditions of ecosystems. These impacts can persist after removal of the invader as ‘legacy-effects’. I assessed whether the invasion of native Cumberland Plain Woodland (CPW) by African olive, Olea europaea subsp. cuspidata, alters soil (a)biotic properties and, if so, the effect it has on the performance of five native CPW species. I then tested whether native soil inocula can mitigate the potential biotic impacts on CPW soils. The five study species were grown in mesocosms under five soil treatments; CPW soil, African olive-invaded soil, and invaded soil inoculated with CPW soil, native rhizosphere soil, or both. The impact of soil treatment on various metrics of native plant performance was determined. Olive-invaded soils were found to have higher pH, total carbon, phosphorus, nitrogen, and nitrate nitrogen but lower ammonia nitrogen. Of the study species, only the biomass of Indigofera australis and Dodonaea viscosa increased in olive soils. Nodulation of I. australis did not differ between treatments. In contrast, Acacia implexa biomass and nodulation decreased in invaded soils and responded positively to inocula. Overall, my results suggest that native soil biota may benefit the outcomes of ecological restoration projects only on a species-specific basis.