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Mechanisms of the impact of a weed (grader grass, Themeda quadrivalvis) on reptile assemblage structure in a tropical savannah

Abom, Rickard and Vogler, Wayne and Schwarzkopf, Lin (2015) Mechanisms of the impact of a weed (grader grass, Themeda quadrivalvis) on reptile assemblage structure in a tropical savannah. Biological Conservation, 191 . pp. 75-82. ISSN 0006-3207

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Article Link(s): http://dx.doi.org/10.1016/j.biocon.2015.06.016

Publisher URL: http://www.sciencedirect.com/science/article/pii/S0006320715002396

Abstract

Invasive grasses are among the worst threats to native biodiversity, but the mechanisms causing negative effects are poorly understood. To investigate the impact of an invasive grass on reptiles, we compared the reptile assemblages that used native kangaroo grass (Themeda triandra), and black spear grass (Heteropogon contortus), to those using habitats invaded by grader grass (Themeda quadrivalvis). There were significantly more reptile species, in greater abundances, in native kangaroo and black spear grass than in invasive grader grass. To understand the sources of negative responses of reptile assemblages to the weed, we compared habitat characteristics, temperatures within grass clumps, food availability and predator abundance among these three grass habitats. Environmental temperatures in grass, invertebrate food availability, and avian predator abundances did not differ among the habitats, and there were fewer reptiles that fed on other reptiles in the invaded than in the native grass sites. Thus, native grass sites did not provide better available thermal environments within the grass, food, or opportunities for predator avoidance. We suggest that habitat structure was the critical factor driving weed avoidance by reptiles in this system, and recommend that the maintenance of heterogeneous habitat structure, including clumping native grasses, with interspersed bare ground, and leaf litter are critical to reptile biodiversity.

Item Type:Article
Business groups:Biosecurity Queensland
Keywords:Grader grass Invasive weeds Native grass habitats Reptile abundance and richness Themeda quadrivalvis
Subjects:Science > Invasive Species > Plants
Plant pests and diseases > Weeds, parasitic plants etc
Animal culture > Reptiles
Deposited On:09 Feb 2016 02:58
Last Modified:23 Jan 2017 06:12

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