Question To what extent do dominant species population sources and subordinate species pools affect diversity and composition of an assembling grassland community? Location Illinois, USA. Methods Percentage cover of all species were recorded annually in 36 1‐m2 quadrats assigned to a factorial combination of dominant species population source (functionally distinct cultivar or non‐cultivar seed source) and designed species pool (three levels varying in species identity, but with equal functional group representation and richness) during the first 4 yr of community assembly in an experimental grassland restoration. Results Univariate and multivariate analyses showed that individual species abundance, life form and community composition differed significantly among designed species pools, but were not strongly affected by population source of the dominant species (cultivar or non‐cultivar). There were fewer C4 species in cultivar plots but only in one of three designed species pools during one of 4 yr of community assembly. The number of legume and forb species was higher in cultivar plots, but also only in one of the 4 yr of study. Other changes in species richness and abundance were solely related to successional change. Conclusions Non‐dominant species introduced to restore plant communities strongly affects plant community composition, and composition can show fidelity to designed species pools. Only marginal or temporary effects of dominant species seed source were observed in the assembling plant community. Thus, we found no strong evidence that the source of dominant species, in this case cultivars compared to local ecotypes, has consequences for community assembly in the early stages of restoration (1–4 yr). The absence of a strong dominant species source effect may be exacerbated by the assembly of diverse plant communities, resulting in a stronger effect of subordinate species seed mixture in restoration.

Genetic principles underlie recommendations to use local seed, but a paucity of information exists on the genetic distinction and ecological consequences of using different seed sources in restorations. We established a field experiment to test whether cultivars and local ecotypes of dominant prairie grasses were genetically distinct and differentially influenced ecosystem functioning. Whole plots were assigned to cultivar and local ecotype grass sources. Three subplots within each whole plot were seeded to unique pools of subordinate species. The cultivar of the increasingly dominant grass, Sorghastrum nutans, was genetically different than the local ecotype, but genetic diversity was similar between the two sources. There were no differences in aboveground net primary production, soil carbon accrual, and net nitrogen mineralization rate in soil between the grass sources. Comparable productivity of the grass sources among the species pools for four years shows functional equivalence in terms of biomass production. Subordinate species comprised over half the aboveground productivity, which may have diluted the potential for documented trait differences between the grass sources to influence ecosystem processes. Regionally developed cultivars may be a suitable alternative to local ecotypes for restoration in fragmented landscapes with limited gene flow between natural and restored prairie and negligible recruitment by seed.

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. 2018. Functional diversity is more sensitive to biotic filters than phylogenetic diversity during community assembly. Ecosphere 9(3):e02164. 10. 1002/ecs2.2164 Abstract. Ecologically important functional traits and phylogenetic relatedness may provide mechanistic insight into biotic filters influencing community assembly. To assess this, we examined the relationship between functional diversity (FD, functional trait relatedness) and phylogenetic diversity (PD, evolutionary relatedness) during grassland restoration. Temporal changes in FD and PD were used to examine the effect of two biotic filters during community assembly: intraspecific variation in dominant species (different population sources) and interspecific variation among subordinate species (phylogenetically distinct species pools). The experimental grassland restoration contained whole plots sown with either cultivars or local ecotypes of three dominant grasses (Sorghastrum nutans, Andropogon gerardii, and Schizachyrium scoparium). Each whole plot contained subplots sown with three phylogenetically distinct pools of subordinate species. Cover of all species was measured in permanent sampling areas for ten years, and 10 functional traits were measured for 88 species, allowing calculation of PD and FD, respectively. Overall, the communities establishing with local ecotypes of the dominant grasses were functionally more dissimilar than when established with cultivars, particularly among the Asteraceae, suggesting competitive exclusion of functionally dissimilar species by cultivars. This result was opposite to our prediction that cultivars through limiting similarity would exclude more similar species more so than would local ecotypes. The effect of the dominant grass population source was contingent upon interactions with species pools. A supplemental propagule addition of functionally dissimilar species four years since initial sowing increased FD, but this effect varied among species pools. A lack of relationship between FD and PD in this system indicated that measuring PD alone without inclusion of functional traits may miss additional factors affecting species coexistence. In addition, the variation in FD between population sources and among species pools indicated that the measured traits were more sensitive to these factors than to their phylogenetic relationships. This analysis of long-term data from a field experiment showed new consequences of using different seed sources and species pools (as biotic filters), and supplemental seeding on PD and FD of restored grassland. Quantifying relevant functional traits in a phylogenetic framework could help identify plant population sources that enhance coexistence of desirable species.