Biotic and Abiotic Effects of Remnant and Restoration Soils on the Performance of Tallgrass Prairie Species

Abstract

Interactions between plants and soil microbes are increasingly recognized as an important component in the functioning of ecosystems. Because these interactions affect and are affected by soil abiotic conditions, restoration efforts must consider the interactions between the plant community, the soil community, and the soil abiotic conditions. We sampled soil from 20 independently restored tallgrass prairies and 8 natural prairie remnants in southern Manitoba. Soils from the restored sites had 4.5 times higher phosphate levels than soils from the remnants. In whole soil assays, big bluestem (Andropogon gerardii ) and Culver's root (Veronicastrum virginicum) had significantly greater growth in soil from the remnant sites. A second growth assay using sterile and inoculated soil from a subset of these sites showed that while big bluestem benefited from soil biota on both remnants and restored sites, the effect was twice as strong on the remnant sites. Our results suggest that plants on restored prairies are less reliant on soil microbes due to the higher fertility found within their soils. Our data suggests that like other ecosystems, residual high fertility in tallgrass prairies may facilitate invasion by non-native plants.

Plant–microbe interactions change along a tallgrass prairie restoration chronosequence

“…The data presented here suggest that restored prairies may become dominated by grasses because the soil microbial communities of post‐agricultural restorations initially favor dominant matrix grasses at the expense of forbs. Similar to our findings, Faber and Markham () found differences in the feedbacks associated with remnant and restored prairies. However, the microbial community of remnant sites in that study produced positive feedbacks on A. gerardii growth, whereas our live remnant soil inoculates produced negative feedbacks.…”

“…This variation among sites and species could be due to changes in soil characteristics or species‐specific interactions (Middleton & Bever ), despite the usage of small amounts of soil inocula relative to the volume of fertile potting mix. Shifts in plant performance with abiotic soil properties are not uncommon in such studies (Anderson ; Faber & Markham ).…”

“…Plant–soil feedbacks are generated by plants inducing changes in the composition of their soil microbial community, which then affects plant performance (Bever ; Bever et al ). If changes in soil biota increase performance relative to other plants, the positive feedback may increase abundance, maintain dominance and slow successional replacement (Reynolds et al ; Kardol et al ; Faber & Markham ). Beneficial microbes such as nitrogen fixing bacteria and mycorrhizal fungi can directly enhance plant fitness by allowing greater access to mineral resources (Allen & Allen ; Smith et al ; Kardol et al ; Bever et al ; Fitzsimons & Miller ; Hodge & Fitter ).…”

Super‐abundant C4 grasses are a mixed blessing in restored prairies

“…Big bluestem and little bluestem were the most abundant C 4 grasses in most of the prairies we sampled, probably at least partly because they were often sown in high densities. Site characteristics may also explain why restored prairies host high big and little bluestem abundance, including legacies of fertilization (Baer et al 2004; Faber & Markham 2012), altered microbial communities (Scott & Baer 2018), landscape context (Grman et al 2013; Zirbel et al 2019), or other factors. High big bluestem abundance may also be driven by unique traits of big bluestem.…”