Seeding tallgrass prairie in monospecific patches promotes native species establishment and cover

Abstract

In tallgrass prairie reconstruction, the way desired seeds are arranged on the landscape may affect species establishment, species persistence, and the establishment and persistence of undesired (nonseeded) species from the local propagule pool. To test effects of species seeding pattern on how grasslands develop spatially, we seeded 20—4 × 4–m bare soil plots with 16 tallgrass prairie species. Treatment plots were divided into 16—1 × 1–m subplots, 64—0.5 × 0.5–m subplots, 256—0.25 × 0.25–m subplots, or 1,024—0.125 × 0.125–m subplots. Each species was hand broadcast into separate subplots (1 m2 total area/species) within each plot. An additional treatment included uniformly mixing and broadcasting all seeds across a plot. We recorded species cover at the 0.125 × 0.125–m scale within each plot at the beginning of the second and third growing seasons. While species persistence was greatest within plots seeded with larger subplots, plots with smaller subplots were more spatially diverse and less occupied by nonseeded species over time than larger subplot and mixed plots. As is common in reconstruction efforts, establishment was variable among species and seeding with monospecific subplots enhanced colonization of desired rhizomatous species (e.g., Heliopsis helianthoides, Monarda fistulosa, Elymus virginicus) into unoccupied locations at the expense of species from the local propagule pool. Results suggest that seeding species in smaller, monospecific patches could result in grasslands with a more balanced native species composition than those established with a seed mixture approach.

Helianthus maximiliani and species fine‐scale spatial pattern affect diversity interactions in reconstructed tallgrass prairies

“…As in other studies (Dickson & Busby, ; Kordbacheh, Jarchow, English, & Liebman, ; Nemec, Allen, Helzer, & Wedin, ; Seahra et al, ), a productive Heliantheae forb initially dominated our experimental tallgrass prairies reconstructed on a former agricultural field. To address this statistically, we allowed diversity effects in our DI models to differ in H. maximiliani plots and treated these plots with a different variance structure.…”

“…This is useful when considering to what extent plant species fine-scale spatial relationships affect plot-scale diversity effects. Plant species interact on finite-scales, and if their interaction distances are small enough, their spatial relationships can presumably affect the interactions they experience and respond to (Houseman, 2014;Lamošová, Doležal, Lanta, & Lepš, 2010;Murrell, 2010;Porensky, Porensky, Vaughn, & Young, 2012;Seahra, Yurkonis, & Newman, 2019;Stoll & Prati, 2001;Yurkonis & McKenna, 2014). In spatially manipulated tallgrass prairies, increasing species interspecific interactions increased biomass and favored clonal forbs (McKenna & Yurkonis, 2016), an effect that was replicated by seeding species in smaller conspecific patches (Seahra, Yurkonis, & Newman, 2016).…”

Long‐term experiment manipulating community assembly results in favorable restoration outcomes for invaded prairies

“…Despite the difficulties of seedling establishment in early restoration due to these stresses, our findings emphasize the importance of adding seeded species early in the process before competitively dominant species reach high cover. For the integration of target species which, as in our case, do not establish when seeded early nor are likely to establish when seeded in later, other approaches might be necessary, such as creating microhabitats, creating weeded monospecific patches, or selectively transplanting adult specimens (Drayton & Primack 2000;Seahra et al 2019).…”

Why are some plant species missing from restorations? A diagnostic tool for temperate grassland ecosystems

“…Another study by Seahra et al (2019) identified competition as a bottleneck to species establishment by comparing species performance when they were sown alone versus in mixtures with other species. Most of the studied target species showed greater establishment when sown alone than in mixtures.…”