Early-successional plant species invest in rapid growth and reproduction in contrast to slow growing late-successional species. We test the consistency of "trade-offs between plant life history and responsiveness on arbuscular mycorrhizal fungi. We selected four very early-, seven early-, 11 middle-, and eight late-successional plant species from six different families and functional groups and grew them with and without a mixed fungal inoculum and compared root architecture, mycorrhizal responsiveness, and plant growth rate. Our results indicate mycorrhizal responsiveness increases with plant successional stage and that this effect explains more variation in mycorrhizal response than is explained by phylogenetic relatedness. The mycorrhizal responsiveness of individual plant species was positively correlated with mycorrhizal root infection and negatively correlated with average plant mass and the number of root tips per unit mass, indicating that both plant growth rate and root architecture trade off with investment in mycorrhizal mutualisms. Because late-successional plants are very responsive to mycorrhizal fungi, our results suggest that fungal community dynamics may be an important driver of plant succession.

Summary Because soil microbial communities are often altered by anthropogenic disturbance, successful plant community restoration may require the restoration of beneficial soil microbes, such as arbuscular mycorrhizal (AM) fungi. Recent evidence suggests that later successional grassland species are more strongly affected by AM fungi relative to early successional plants and that late successional plants consistently benefit from some AM fungi but not other AM fungal species. Many of these late successional species are also often missing in restorations despite being heavily seeded. To assess the effects of AM fungal composition within grassland restorations, we inoculated plots with six different AM fungal community treatments including one of four different AM fungal species isolated from a prairie, a mixture of all four fungal species, and a non‐inoculated control. AM fungi were introduced by planting 16 different inoculated nurse plants into replicated plots. We also seeded the restoration with a diverse, 54 species prairie seed mixture. We found that AM fungal inoculation drove plant community composition; plots inoculated with certain AM fungal treatments were dominated by desirable prairie plants, whereas plots inoculated with other AM fungal species and the non‐inoculated control were dominated by non‐desirable plants including weeds and exotic species. Specifically, we found that many early successional species established well regardless of AM fungal inoculation, whereas the establishment and growth of many late successional species was strongly dependent on the presence of specific AM fungal species. Many conservative late successional species did not occur without inoculation. Overall, total plant community richness, diversity, and Floristic Quality Index were all significantly improved with AM fungal inoculation, whereas we observed that non‐desirable plant abundance was significantly greater in the non‐inoculated plots. Synthesis and applications. Our results suggest that the lack of late successional establishment reported in many previous restorations may be due to ineffective arbuscular mycorrhizal fungal communities at these sites. We conclude that the reintroduction of arbuscular mycorrhizal fungi from reference prairie environments could improve restoration outcomes by promoting plant diversity and richness, especially for desirable later successional plant species, while simultaneously inhibiting less desirable weedy plants.

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Soil microbial communities contribute to ecosystem function and structure plant communities, but are altered by anthropogenic disturbance. Successful restoration may require microbial community restoration. Inoculation of plants with arbuscular mycorrhizal fungi (AMF) may improve ecological restoration, but AMF species that are locally adapted to native plant communities are often unavailable and commercially propagated AMF are not necessarily locally adapted to the desired plant community target. The disconnect between readily available commercial fungi and later‐successional plants may inhibit successful establishment of the restoration. We tested this concept using four mid‐ to late successional prairie plant species planted with one of three inoculum sources: a locally adapted AMF mix cultured from native prairie, a non‐locally adapted commercial AMF product, or a sterilized background soil control. The inoculated plants (termed nurse plants) were planted in the middle of field plots. In each plot, uninoculated plants (test plants) were planted at 0.5, 1, and 2 m from the nurse plants in order to test whether growth and survival of test plants could be affected by inoculum source. Generally, plants grew larger when inoculated with native AMF compared to commercial inoculum or the control. Later successional species responded most positively to native AMF. Benefits of inoculation also spread to neighbors, as uninoculated late successional test plant, Sporobolus heterolepis, grew larger when its' neighbors were inoculated with native AMF than with commercial AMF or the control. Due to an unanticipated herbivory event, we also assessed the degree to which rate of herbivory or plant tolerance to herbivory is affected by inoculum source. The mid‐ successional nurse plant, Ratibida pinnata, received the majority of the herbivore damage, and when it was inoculated with commercial AMF, it experienced significantly more herbivory than plants inoculated with native AMF or the control. R. pinnata inoculated with native AMF grew significantly larger one month following herbivory, though there was no significant difference in growth in the second year of sampling. This study suggests that native, locally adapted AMF can improve restoration of prairie plant species and these benefits can extend to neighbors up to two meters from the inoculation point.