Native arbuscular mycorrhizal fungi promote native grassland diversity and suppress weeds 4 years following inoculation

Abstract

Restoration quality of native prairie can be improved by reintroducing key organisms from the native plant microbiome such as arbuscular mycorrhizal (AM) fungi. Here, we assess whether the positive effects of a native mycorrhizal inoculation observed during the first growing season remained at the end of the fourth growing season. In 2016, an experiment was initiated that assessed the response of a restored tallgrass prairie to an inoculation density gradient of native mycorrhizal fungi ranging from 0 to 8,192 kg/ha. First year results indicated that native plant establishment benefited from high but not low densities of native mycorrhizal inocula, resulting in improvements in native plant abundance, richness, and diversity. To assess whether these effects persist in later growing seasons, we resampled the prairie restoration in 2020 and analyzed the data similarly. Results from the fourth growing season indicated that the pattern of responses had persisted; the positive effects of inoculation observed during the first growing season remained after four growing seasons as demonstrated by improvements in total and native plant diversity and reduced non‐native abundance. Additionally, the low densities of mycorrhizal amendment that were not initially effective were found to reduce non‐native abundance in the fourth growing season, suggesting that low densities of mycorrhizal amendment can be amplified via positive plant‐AM fungal feedback to suppress weeds following the introduction of lesser amounts of AM fungi.

Tracking arbuscular mycorrhizal fungi to their source: active inoculation and passive dispersal differentially affect community assembly in urban soils

“…Beneficial plant growth effects of inoculation have not been observed in prior green roof inoculation research (Young et al ., 2015; Rumble & Gange, 2017). It is possible that a plant growth response to AM fungal inoculation was not observed due to the relatively short duration of the experiment or because in field experiments, positive plant growth effects of inoculation are more likely observed over time (Requena et al ., 2001; Koziol et al ., 2022). Belowground AM fungal community shifts may preempt aboveground shifts or plant benefits may manifest in ways that were not measured (e.g.…”

“…The beneficial effect of AM fungal inoculation can be particularly pronounced in the case of extreme soil disturbances such as topsoil removal (Molineux et al ., 2015; Wubs et al ., 2016). Additionally, the beneficial effects of bioinoculants can increase after multiple years (Requena et al ., 2001; Koziol et al ., 2022), suggesting the importance of examining the effects of AM fungal inoculation and passive establishment over time (John et al ., 2014; Yang & Davidson, 2021).…”

Three‐way fungal interactions affect the potential biological control of Himalayan balsam, Impatiens glandulifera

“…We suggest that a similar strategy could be employed in areas invaded by I. glandulifera ; control of the weed could be improved by direct action of AM fungi, coupled with altered interspecific competition, thereby leading to increased plant diversity (Van Der Heijden et al, 2008). A similar approach has been used in American prairie grasslands with good success (Koziol et al, 2022). The Symbio product contains a number of native fungal species, but extensive field testing is required to ensure that these fungi can establish sustainable populations, since some commercial products have been shown to have little persistence in field soils (Berruti et al, 2017).…”

Crop Productivity Boosters: Native Mycorrhizal Fungi from an Old-Growth Grassland Benefits Tomato (Solanum lycopersicum) and Pepper (Capsicum annuum) Varieties in Organically Farmed Soils

“…Here, we show that adding a consortium of native fungi known to be beneficial can have season-long benefits in organic agricultural systems. Past work has shown that applications of native AM fungi sourced from old-growth habitats can also benefit perennial cropping systems [ 10 , 26 ] and native system restorations [ 29 , 30 ]. Taken together, these data reveal a pattern where applications of native fungi sourced from old-growth ecosystems can benefit plants in a multitude of environments, from restoration to organic agriculture, due to the increased beneficial function of the fungi isolated from old-growth native habitats.…”

“…Crops were transplanted as non-inoculated seedlings, and a native AM fungi consortium was applied at the time of planting. These native fungi were isolated from an old-growth grassland and known to be beneficial to perennial cropping systems [ 10 , 26 ] and native systems [ 29 , 30 ]. Crop productivity was assessed throughout an entire growing season.…”