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A primary goal of restoration ecology is to understand the factors that generate variability in species diversity and composition among restorations. Plant communities may assemble deterministically toward a common community type, or they may assemble stochastically, ending differently because of weather conditions during establishment, soil legacy effects, or exotic species propagule pressure. To test these alternative hypotheses, we sampled plant communities and soil at 93 randomly selected restored prairies distributed throughout Iowa, USA. Five remnant sites were sampled as a reference. We tested our hypotheses using multiple regressions and investigated the strength of direct and indirect effects on species diversity and richness using structural equation models. The prairie restorations were highly variable in their age, size, diversity, soil characteristics, and how they were managed post‐seeding. The strongest predictor of plant species richness and diversity was the degree of invasion, as measured by the abundance of exotic species. Restorations planted with species‐rich seed mixes had reduced exotic species abundance, which led indirectly to higher species richness of restorations. Sites with higher organic matter and a more linear shape had a direct positive effect on exotic abundance, which in turn decreased diversity. We found little support for deterministic assembly, and diversity did not increase with the age of planting. Our results indicate that restored prairie communities tend to assemble into states of high or low diversity, driven by invasion from exotic plant species. Management of exotic species is essential for maximizing species diversity in temperate grassland restorations. [ABSTRACT FROM AUTHOR]

Abstract: Ecological restoration and revegetation efforts entail the translocation of native plant populations. Risks associated with these efforts include failure of translocated populations to establish or, conversely, such strong establishment that they excessively dominate the recipient community. The role that selective breeding plays in mediating these risks is unclear but of increasing importance as efforts to restore and establish multifunctional grasslands also increase. In a three‐year, spatially replicated study, we seeded experimental prairie communities with either domesticated (cultivar) or undomesticated strains of Panicum virgatum (switchgrass), a North American C4 species under development as a biomass crop. We evaluated the composition, performance, and diversity of the recipient plant communities and compared the performance of cultivar and undomesticated switchgrass in those communities. We found little evidence that switchgrass population source affected community response. Switchgrass cultivars modestly exceeded undomesticated strains with respect to stand establishment, third‐year stand density, and aboveground biomass; effect size and significance differed among sites. Our results suggest that including cultivars in ecological restorations and multifunctional grasslands may enhance success of switchgrass establishment with little risk of impairing the composition or diversity of plant communities for up to three years, as reflected in the measures used here. However, the incorporation of undomesticated switchgrass into multifunctional grasslands may enhance landscape‐scale genetic variation and mitigate risks associated with gene flow between translocated and local wild switchgrass populations; more research on these dynamics is needed. [ABSTRACT FROM AUTHOR]

The positive relationship between plant diversity and ecosystem functioning has been criticized for its applicability at large scales and in less controlled environments that are relevant to land management. To inform this gap between ecological theory and application, we compared recovery rates of belowground properties using two chronosequences consisting of continuously cultivated and independently restored fields with contrasting diversity management strategies: grasslands restored with high plant richness and managed for diversity with frequent burning ( n = 20) and grasslands restored with fewer species that were infrequently burned ( n = 15). Restoration and management for plant diversity resulted in 250% higher plant richness. Greater recovery of roots and more predictable recovery of the active microbial biomass across the high diversity management strategy chronosequence corresponded with faster recovery of soil structure. The high diversity grasslands also had greater nutrient conservation indicated by lower available inorganic nitrogen. Thus, mesic grasslands restored with more species and managed for high plant diversity with frequent burning enhances the rate of belowground ecosystem recovery from long-term disturbance at a scale relevant to conservation practices on the landscape. [ABSTRACT FROM AUTHOR]

The evaluation of ecosystem quality is inherently subjective, requiring decisions about which variables to notice or measure, and how these variables are integrated into a coherent evaluation. Despite the central role of human judgment, few evaluation methods address the subjectivity that is inherent in their design. There are, however, advantages to directly using opinion to create an expert system where the metric is constructed around opinion data. These advantages include stakeholder inclusion and the encouragement of a dialogue of data-driven criticism rather than subjective counter-opinion. We create an expert system to express the quality of a grassland ecosystem in Australia. We use an ensemble of bagged regression trees trained on calibrated expert preference data, to model the perceived quality of this grassland using a set of eight site variables as inputs. The model provides useful predictions of grassland quality, producing predictions similar to real expert evaluations of independent synthetic test sites not used to train the model. We apply the model to real grassland sites ranging from pristine to highly degraded, and confirm that our model orders the sites according to their degree of modification. We demonstrate that the use of too few experts produces relatively poor results, and show that for our problem the use of data from over twenty experts is appropriate. The scaling approach we used to calibrate between-expert data is shown to be an appropriate mechanism for aggregating the opinions of multiple experts. The resultant model will be useful in many contexts, and can be used by managers as a tool to evaluate real sites. It can also be integrated into ecological models of change as a means of evaluating predicted changes, for example, as a measure of utility when combined with cost estimates. The basic approach demonstrated here is applicable to any ecosystem, and we discuss the opportunities and limitations of its wider use. [ABSTRACT FROM AUTHOR]

The article discusses the study which investigates the post-seeding establishment of native plants in grassland restoration plots sown at densities crossed with levels of species richness in former arable land in Nebraska. The study used rainfall manipulation structures to evaluate drought resistance and resilience of restored plants. Results show that little evidence of differential drought resistance and recovery among seeding treatments are found.

The article presents an experimental wet-prairie restorations that aims to determine the reasons why restored communities develop as they do. Divergent successions in plantings of 16 tallgrass prairie species sown in equal densities in Wisconsin showed strong effects of vole (Microtus pennsylvanicus) herbivory on vegetation initially protected for an establishment period of over 24 months, by which time all principal species were flowering and fruiting.

The article presents a study that determines the measurement of soil surface carbon dioxide flux in grasslands using static or dynamic chambers. It offers overview of the method of the study that uses empirical model based on soil temperature, water content, and leaf area index (LAI). The result of the study suggests that carbon dioxide flux on soil temperature and water content is dependent on the photosynthetic capacity of the canopy.

Tractable practices for soil microbial restoration in tallgrass prairies reclaimed from agriculture are a critical gap in traditional ecological restoration. Long‐term fertilization and tilling permanently alter soil bacterial and fungal communities, requiring microbe‐targeted restoration methods to improve belowground ecosystem services and carbon storage in newly restored prairies. These techniques are particularly important when restoring for climate‐ready ecosystems, adapted to altered temperature regimes. To approach these issues, we conducted a multi‐factorial greenhouse experiment to test the effects of plant species richness, soil amendment and elevated temperature on soil microbial diversity, growth, and function. Treatments consisted of three seedlings of one plant species (Andropogon gerardii) or one seedling each of three plant species (A. gerardii, Echinacea pallida, Coreopsis lanceolata). Soil amendments included cellulose addition, inoculation with a microbial community collected from an undisturbed remnant prairie, and a control. We assessed microbial communities using extracellular enzyme assays, Illumina sequencing of the bacterial 16S rRNA gene, predicted bacterial metabolic pathways from sequence data and phospholipid fatty acid analysis (PLFA), which includes both bacterial and fungal lipid abundances. Our results indicate that addition of cellulose selects for slow‐growing bacterial taxa (Verrucomicrobia) and fungi at ambient temperature. However, at elevated temperature, selection for slow‐growing bacterial taxa is enhanced, while selection for fungi is lost, indicating temperature sensitivity among fungi. Cellulose addition was a more effective means of altering soil community composition than addition of microbial communities harvested from a remnant prairie. Soil water content was typically higher in the A. gerardii treatment alone, regardless of temperature, but at ambient temperature only, predicted metagenomics pathways for bacterial carbon metabolism were more abundant with A. gerardii. In summary, these results from a mesocosm test case indicate that adding cellulose to newly restored soil and increasing the abundance of C4 grasses, such as A. gerardii, can select for microbial communities adapted for slow growth and carbon storage. Further testing is required to determine if these approaches yield the same results in a field‐level experiment. [ABSTRACT FROM AUTHOR]