Does Invasive Mammal Exclusion Restore an Ecosystem Function Mediated by Invertebrates?

Area of Science:

• Ecology
• Conservation Biology
• Ecosystem Function Restoration

Background:

• Invasive mammals threaten biodiversity and ecosystem functions, particularly on islands.
• Restoration of invertebrate-mediated ecosystem functions after invasive mammal removal is poorly understood.
• Litter decomposition, pollination, and herbivory are key invertebrate-provided functions.

Purpose of the Study:

• To determine if invasive mammal removal restores invertebrate-mediated decomposition.
• To compare decomposition rates in ecosanctuaries (mammals removed except mice) and non-ecosanctuaries.
• To investigate the influence of invertebrate communities and vegetation changes on decomposition.

Main Methods:

• Measured decomposition of native tree litter (Melicytus ramiflorus) using litterbags with different mesh sizes.
• Compared decomposition rates across paired ecosanctuary and non-ecosanctuary sites in Aotearoa/New Zealand.
• Analyzed the role of invertebrate communities and vegetation composition.

Main Results:

• Ecosanctuaries exhibited increased decomposition compared to non-ecosanctuaries, but this varied by litterbag mesh type.
• Greater decomposition occurred in coarse-mesh bags within ecosanctuaries, suggesting a role for larger invertebrates.
• Fine-mesh bags showed similar decomposition rates, indicating potential differences in smaller invertebrate contributions or other factors.

Conclusions:

• Invasive mammal eradication can restore invertebrate-driven ecosystem functions, specifically decomposition.
• The presence of diverse and abundant detritivore communities in ecosanctuaries likely enhances decomposition.
• Further research is needed to assess the restoration of other invertebrate-mediated functions like pollination and pest control.