Data from: Grassland restoration characteristics influence phylogenetic and taxonomic structure of plant communities and suggest assembly mechanisms

1. Phylogenetic and species-based taxonomic descriptions of community
structure may provide complementary information about the mechanisms
driving community assembly across different environments. Environmental
filtering may have similar effects on taxonomic and phylogenetic diversity
under the assumption of niche conservatism, whereas competitive exclusion
could produce contrasting patterns in these diversity metrics. In
grassland restorations, these diversity patterns might then reveal
potential assembly mechanisms underlying the impacts of restoration and
management conditions on community structure. 2. We compared plant
community structure (alpha diversity, composition, and within-site beta
diversity) from both phylogenetic and taxonomic perspectives. Using
surveys from 120 tallgrass prairie restorations in four regions of the
Midwestern United States, we examined the effects of four potential
drivers or environmental gradients: precipitation in the first year of
restoration, seed mix richness, time since last prescribed fire, and
restoration age, and included soil conditions as a covariate. 3.
First-year precipitation influenced taxonomic community structure, but had
weak effects on phylogenetic diversity and composition. Similarly, greater
seed mix richness increased taxonomic diversity but did not influence
phylogenetic diversity. Taxonomic, but not phylogenetic, diversity
generally was lower in older restorations and those with a longer time
since the last prescribed fire. These drivers consistently explained more
variation in taxonomic than phylogenetic diversity and composition,
perhaps in part because species turnover was largely among related
species, producing weak impacts on phylogenetic community measures. 4. An
impact of precipitation on taxonomic but not phylogenetic diversity
suggests that there may not be large differences in drought tolerance
among clades that would cause phylogenetic patterns to arise from this
environmental filter. Declining taxonomic diversity but not phylogenetic
diversity is consistent with competitive exclusion as an assembly
mechanism when competition is strongest between related species. 5.
Synthesis: This research shows how studying taxonomic and phylogenetic
diversity of ecosystem restorations can inform plant community ecology and
help natural resource managers better predict the outcomes of restoration
actions and management.