Eaten out of house and home: impacts of grazing on ground-dwelling reptiles in Australian grasslands and grassy woodlands

PLoS One. 2014 Dec 11;9(12):e105966. doi: 10.1371/journal.pone.0105966. eCollection 2014.

Abstract

Large mammalian grazers can alter the biotic and abiotic features of their environment through their impacts on vegetation. Grazing at moderate intensity has been recommended for biodiversity conservation. Few studies, however, have empirically tested the benefits of moderate grazing intensity in systems dominated by native grazers. Here we investigated the relationship between (1) density of native eastern grey kangaroos, Macropus giganteus, and grass structure, and (2) grass structure and reptiles (i.e. abundance, richness, diversity and occurrence) across 18 grassland and grassy Eucalyptus woodland properties in south-eastern Australia. There was a strong negative relationship between kangaroo density and grass structure after controlling for tree canopy cover. We therefore used grass structure as a surrogate for grazing intensity. Changes in grazing intensity (i.e. grass structure) significantly affected reptile abundance, reptile species richness, reptile species diversity, and the occurrence of several ground-dwelling reptiles. Reptile abundance, species richness and diversity were highest where grazing intensity was low. Importantly, no species of reptile was more likely to occur at high grazing intensities. Legless lizards (Delma impar, D. inornata) were more likely to be detected in areas subject to moderate grazing intensity, whereas one species (Hemiergis talbingoensis) was less likely to be detected in areas subject to intense grazing and three species (Menetia greyii, Morethia boulengeri, and Lampropholis delicata) did not appear to be affected by grazing intensity. Our data indicate that to maximize reptile abundance, species richness, species diversity, and occurrence of several individual species of reptile, managers will need to subject different areas of the landscape to moderate and low grazing intensities and limit the occurrence and extent of high grazing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Australia
  • Biodiversity
  • Conservation of Natural Resources
  • Eating*
  • Eucalyptus
  • Forests*
  • Grassland*
  • Macropodidae / physiology*
  • Poaceae
  • Principal Component Analysis
  • Reptiles / physiology*
  • South Australia

Grants and funding

Financial support was provided by Canberra Birds Conservation Fund to BH (http://cbcf.canberrabirds.org.au), Bush Heritage Andyinc Foundation Environmental Research Postgraduate Scholarship to BH (http://www.bushheritage.org.au) and the Australian Government's Department of Industry, Innovation, Science, Research and Tertiary Education Australian Postgraduate Award to BH (http://www.innovation.gov.au/research/researchblockgrants/pages/australianpostgraduateawards.aspx). Financial support was provided to BH by the Australian Government for monitoring activities undertaken at a single property used in this research. AM was funded by ARC Future fellowship FT 100100358. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.