Legacy effects of a range-expanding shrub influence soil fungal communities and reduce conspecific seedling performance

Abstract Aims Soil legacy effects can have long-term impacts on soil microbial communities with implications for plant growth and community structure. These effects are well studied for invasive plants, particularly after removal of invasive species, however very little work has considered the soil legacy effects of native range expanding species. Methods We used a controlled greenhouse experiment with a range-expanding sagebrush species (Artemisia rothrockii (Asteraceae)) to determine how sagebrush seedling performance was influenced by soil legacy effects of sagebrush in both the native and expansion range and over time since removal. We then used ITS2 sequencing to determine what soil microbial mechanisms drove these feedbacks. Results Conspecific sagebrush seedlings responded negatively to sagebrush soil legacy effects overall, with more negative plant-soil feedbacks, reduced height, and higher root:shoot ratios in shrub removal inoculum than in shrub and herbaceous soil inoculum. Seedlings with shrub removal inoculum had increased fungal diversity, pathogen, and saprotroph richness, and altered fungal community composition. Legacy effects on soil fungal diversity and functional group richness were present in seedlings with 1-year shrub removal inoculum, while effects on fungal community composition were found in 1 and 5-year shrub removal inoculated seedlings. Similarly, negative plant-soil feedbacks occurred for seedlings growing in both 1-year and in 5-year shrub removal inoculum. Conclusions This work provides novel insight into how soil legacy effects of native range expanding species may limit rather than promote the recruitment of conspecifics, with important implications for management as global change continues to shift the geographic ranges of woody plants.