1. Ecosystem restoration often focuses on reestablishing species richness and diversity of native organisms, especially plants. However, effective restoration requires re-establishment of ecosystem functions and processes by all trophic levels. Functional trait descriptions of communities, including decomposer communities, may provide more comprehensive evaluations of restoration activities and management than taxonomic community metrics alone.

2. We examined species and functional trait composition of dung beetle (Coleoptera: Scarabaeidae, Geotrupidae) communities across a  3-31 year chronosequence of restored prairies, in which sites varied in the presence of re-introduced bison and prescribed fire. We calculated functional diversity metrics and community-weighted mean trait values using behavioral and morphological measurements. We also performed a dung decomposition experiment to measure an ecosystem function driven by these insects.

3. Bison presence doubled beetle abundance and increased richness by 50%. Shannon diversity increased with restoration age, nearly doubling from the youngest to oldest restorations. Functional diversity was unchanged, except functional richness, which was reduced by bison and fire presence. Beetles were, on average, smaller in older restorations, although this pattern was weaker when bison were present.

4. Dung decomposition was unaffected by site characteristics but increased with community weighted mean beetle mass. Dung decomposition was better predicted by mean trait values, suggesting that supporting large-bodied species may be more important than species diversity in settings where maximizing decomposition function is a goal.

5. Restoration managers should consider dung beetle communities and their functional characteristics when making management decisions, particularly where large grazers are a component of management strategies.