Biodiversity of indigenous tussock grassland sites in Otago, Canterbury and the Central North Island of New Zealand VI. Coleoptera biodiversity, community structure, exotic species invasion, and the effect of disturbance by agricultural development

Abstract

The diversity of Coleoptera communities in tussock grassland at two sites in Otago, one in Canterbury and one in the central North Island, was compared. The impact of agricultural disturbance on the communities was compared between native tussock, tussock oversown with exotic pasture species and cultivated sown pasture. Coleoptera were heat-extracted from turf samples taken in summer in two consecutive years. In native and oversown treatments, Staphylinidae and Curculionidae predominated in abundance at three of the four sites, and in species richness at all sites and treatments. Carabidae were more species-rich than Curculionidae in cultivated treatments at most sites. The mean density of Coleoptera in native tussock treatments ranged between 654/m² and 97/m². Carnivores were the predominant trophic group followed by herbivores. Species diversity was higher in the native or oversown treatments and the Otago sites were the most diverse overall, and the least disturbed. A total of 19 exotic species were found but there was no relationship with treatment, although their density was higher in cultivated treatments. There was no evidence to suggest that modified vegetation provides a source of exotic Coleoptera species to invade native tussock.

Keywords:

• Coleoptera
• species richness
• species diversity
• habitat disturbance
• lognormal distribution
• exotic species

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Erratum

Acknowledgements

This work was funded by New Zealand's Foundation for Research, Science & Technology through contract C02X0501, the Better Border Biosecurity (B3) programme (www.b3nz.org), and by the Department of Conservation (Science Investigation No. 3667). We thank the many AgResearch staff and students for assistance with sorting samples, especially Rory Logan, Tara Murray, Peter Tozer and Aliesha Kean. We thank Marcus Simons, Don Newman (DoC) and Kath Dickinson (University of Otago) for their continuing support for the study. We thank Al Newton (Field Museum of Natural History, Chicago) for advice on Staphylinidae. We are particularly grateful to Dr Stephan Halloy (Conservation International, Bolivia) for very helpful comments on an earlier draft of this paper.

Notes

This version has been amended. Please see Erratum (http://dx.doi.org/10.1080/03036758.2012.754325).