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1. Ecosystem restoration often focuses on re‐establishing species richness and diversity of native organisms. 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 yearchronosequence 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 behavioural 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 by site characteristics, 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.
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Reintroduced grazers and prescribed fire effects on beetle assemblage structure and function in restored grasslands
Abstract Ecological restoration seeks to reestablish functioning ecosystems, but planning and evaluation often focus on taxonomic community structure and neglect consumers and their functional roles. The functional trait composition of insect assemblages, which make up the majority of animal diversity in many systems, can reveal how they are affected by restoration management and the consequences for ecosystem function. We sampled ground beetle (Coleoptera: Carabidae) assemblages in restored tallgrass prairies varying in management with prescribed fire and reintroduced American bison (Bison bison) to describe their taxonomic and functional trait structure. We also measured seed and arthropod predation to relate management, beetle assemblage characteristics, and function, and to test if function is maximized by trait diversity, dominant trait values, or beetle abundance. Beetle assemblages primarily varied with restoration age, declining over time in richness and both taxonomic and functional diversity, but bison presence also influenced taxonomic composition. Prescribed fire reduced seed predation in summer and arthropod predation in fall. Although seed predation was unrelated to beetle assemblages, arthropod predation was greater in sites with higher abundances of carnivorous ground beetles. The relatively weak impacts of fire and bison on functional assemblage structure is a promising sign that these management disturbances, aimed at supporting a diverse native plant community, are not detrimental to beetle assemblages. The significance of reduced predator function following prescribed fire will depend on the restoration context and whether seed or arthropod predation relates to management goals.
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- Award ID(s):
- 1647502
- PAR ID:
- 10454444
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecological Applications
- Volume:
- 31
- Issue:
- 1
- ISSN:
- 1051-0761
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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