Lizard responses to wildfire in arid interior Australia: Long-term experimental data and commonalities with other studies

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Abstract

Life in terrestrial Australian ecosystems has evolved over the past 10 million years to thrive in habitats kept in a dynamic state through fire succession cycles. Previous studies support the notion that wildfires promote species diversity in plant and animal communities by creating a heterogeneous mix of habitats, each habitat more suitable for particular subsets of species. We document population and community responses to fire in a species-rich lizard assemblage in the Great Victoria Desert of Western Australia. Lizards were censused by pit trapping at a long-unburned flat spinifex site in the Great Victoria Desert in Austral springs of 1992 and 1995. A controlled burn was undertaken in mid-October of 1995, and lizards were censused thereafter in late 1995 and early 1996, and then again in the Austral springs of 1998, 2003 and 2008. Forty-six species of lizards (2872 individuals) were collected and their stomach contents analysed over the course of a 16-year fire succession cycle at this single study site. Most strikingly, relative abundances of two species of agamids varied inversely, responding oppositely to habitat clearing effects of fire. The military dragon Ctenophorus isolepis reached higher abundances when vegetation was dense, and decreased in abundance in open vegetation following fire. The netted dragon Ctenophorus nuchalis was rare when vegetation coverage was high but increased rapidly after fire. Abundances of five species of Ctenotus skinks, C. ariadnae, C. calurus, C. hanloni, C. pantherinus and C. piankai, tracked those of C. isolepis. Abundance of a termite-specialized nocturnal gecko, Rhynchoedura ornata, increased in abundance following fire. Lizard diets changed during the course of the fire succession cycle, returning to near pre-burn conditions after 16 years. In addition to short-term fire succession cycles that contribute to structuring local communities, changes in long-term rainfall also impact desert food webs and regional biotas.

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