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

Abom, Rickard, 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.

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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 ID: 42039
Item Type: Article (Research - C1)
ISSN: 1873-2917
Keywords: grader grass, invasive weeds, native grass habitats, reptile abundance and richness, Themeda quadrivalvis
Funders: Biosecurity Queensland, Department of Agriculture, Fisheries and Forestry, Northern Gulf Resource Management Group
Date Deposited: 08 Dec 2015 14:28
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060208 Terrestrial Ecology @ 50%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060202 Community Ecology (excl Invasive Species Ecology) @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 50%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960510 Ecosystem Assessment and Management of Sparseland, Permanent Grassland and Arid Zone Environments @ 50%
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