Dominant species stabilize pollination services through response diversity, but not cross-scale redundancy

Area of Science:

• Ecology
• Ecosystem Functioning
• Biodiversity Research

Background:

• Biodiversity is hypothesized to stabilize ecosystem function via compensatory dynamics, where species exhibit varied environmental responses.
• Two key forms of compensatory dynamics are cross-scale redundancy (CSR) and response diversity (RD).
• Understanding the empirical measurement and comparison of CSR and RD is crucial for biodiversity-ecosystem functioning research.

Purpose of the Study:

• To develop and apply a novel analytical approach for comparing CSR and RD within the same dataset.
• To investigate the association between CSR, RD, and the stability of native bee pollination of blueberry.
• To determine the relative contributions of species richness, CSR, and RD to ecosystem stability in a real-world agricultural setting.

Main Methods:

• Developed a new analytical method to quantify and compare CSR and RD.
• Studied native bee pollination of blueberry across 16 farms with varying agricultural land use.
• Assessed the relationship between bee species' CSR and RD and the stability of blueberry pollination.

Main Results:

• Both CSR and RD were present in the studied bee communities, but only RD was significantly associated with increased pollination stability.
• The stabilizing effect of RD was primarily driven by the abundance and consistent performance of a single specialist species, Andrena bradleyi.
• The observed stability was more attributable to the 'identity effect' of this key species than to overall species richness.

Conclusions:

• The study successfully demonstrated empirical measurement and comparison of CSR and RD.
• Findings challenge the direct link between biodiversity and ecosystem stability, highlighting the importance of specific species' traits and roles.
• Real-world data indicate that theoretical expectations in biodiversity-ecosystem functioning may not always hold, emphasizing the role of individual species' contributions.