Top-down effects of a large mammalian carnivore in arid Australia extend to epigeic arthropod assemblages

Contos, Peter; Letnic, Mike

doi:10.1016/j.jaridenv.2019.03.002

Cited by 12 publications

(6 citation statements)

References 37 publications

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“…3) and is not particularly noteworthy. Moreover, and despite being a common way of searching for and claiming evidence of mesopredator releases (for examples, see 24,26,[71][72][73] ), such simplistic and correlative comparisons of overall mean PTI between treated and untreated areas cannot and do not elucidate any causal processes and hence cannot be used to make inferences about dingo control-induced mesopredator release 45 (but see also [53][54][55][56][57][58][59][60][61][62] ).…”

Section: Discussionmentioning

confidence: 99%

Terrestrial mesopredators did not increase after top-predator removal in a large-scale experimental test of mesopredator release theory

Castle

Smith

Allen

et al. 2021

Sci Rep

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Removal or loss of top-predators has been predicted to cause cascading negative effects for ecosystems, including mesopredator release. However, reliable evidence for these processes in terrestrial systems has been mixed and equivocal due, in large part, to the systemic and continued use of low-inference study designs to investigate this issue. Even previous large-scale manipulative experiments of strong inferential value have been limited by experimental design features (i.e. failure to prevent migration between treatments) that constrain possible inferences about the presence or absence of mesopredator release effects. Here, we build on these previous strong-inference experiments and report the outcomes of additional large-scale manipulative experiments to eradicate Australian dingoes from two fenced areas where dingo migration was restricted and where theory would predict an increase in extant European red foxes, feral cats and goannas. We demonstrate the removal and suppression of dingoes to undetectable levels over 4–5 years with no corresponding increases in mesopredator relative abundances, which remained low and stable throughout the experiment at both sites. We further demonstrate widespread absence of negative relationships between predators, indicating that the mechanism underpinning predicted mesopredator releases was not present. Our results are consistent with all previous large-scale manipulative experiments and long-term mensurative studies which collectively demonstrate that (1) dingoes do not suppress red foxes, feral cats or goannas at the population level, (2) repeated, temporary suppression of dingoes in open systems does not create mesopredator release effects, and (3) removal and sustained suppression of dingoes to undetectable levels in closed systems does not create mesopredator release effects either. Our experiments add to similar reports from North America, Asia, Europe and southern Africa which indicate that not only is there a widespread absence of reliable evidence for these processes, but there is also a large and continually growing body of experimental evidence of absence for these processes in many terrestrial systems. We conclude that although sympatric predators may interact negatively with each other on smaller spatiotemporal scales, that these negative interactions do not always scale-up to the population level, nor are they always strong enough to create mesopredator suppression or release effects.

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Section: Discussionmentioning

confidence: 99%

Terrestrial mesopredators did not increase after top-predator removal in a large-scale experimental test of mesopredator release theory

Castle

Smith

Allen

et al. 2021

Sci Rep

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“…For the numerical variables, standardized coefficients are reported, and the level of significance is denoted by asterisks ( ns p > 0.05, *p < 0.05, **p < 0.01). consume termites, was greater where dingoes were present due to lower abundances of mesopredators (Contos & Letnic, 2019). Like many other landscapes, there are numerous predators of termites within our study system, including ants, small mammals, lizards and echidnas, and most of these tend to be opportunistic feeders on termites (Pianka, 1986;Tuma et al, 2020) making it difficult to isolate the top-down impacts of predation on termites at a landscape scale, highlighting the need for further studies (Walker et al, 2022).…”

Section: Predictorsmentioning

confidence: 94%

Spatial variability in the contribution of termites to the decay of plant detritus

Wijas,

Letnic,

Cornwell

2024

Austral Ecology

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Drylands are characterized by high spatial variability in resource availability due to sporadic rainfall, topography of the landscape and important effects of animals. Resource availability gradients may trigger patterns in decomposer population abundances and activity, which could affect ecosystem functions such as decomposition. Here, we examined the influence of resource availability gradients on the importance of termites in the decomposition of wood and grass litter. We placed wood blocks and grass litter baits in bags accessible and inaccessible to termites across wood and grass resource gradients as determined by the presence or absence of a top mammalian predator and across topographic gradients during a 9‐month period in arid Australia. We hypothesized that grass‐eating termite activity would track grass abundance and wood‐eating termite activity would track wood abundance. Termites were the predominant decomposition agent at these sites. Termites contributed to 99.5% of wood decomposition and 83.9% of grass decomposition during our study period. For wood, the termite effect was spatially variable and increased with habitat wood availability, which was greatest on dunes and where top predators were absent. However, the contribution of termites to grass litter decomposition did not track grass availability or termite abundance. The highest effects of termites on grass decomposition rates were found in habitats where the absence of top predators led to low grass availability. Our findings highlight how spatial variability in resources in addition to other factors that we do not document but are known to be influenced by the presence of top predators, such as insectivore predation rates, across the landscape could affect ecosystem functions such as decomposition.

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“…However, partial restoration is possible by mitigating threats including, removing introduced animals and artificial watering points, reducing populations of native herbivores and reintroducing regionally extinct species (Moseby, Hill, & Read, 2009; Silcock & Fensham, 2019). These measures can improve the composition and functionality of the desert ecosystem, restoring vegetation composition and cover, and increasing abundances and diversity of some fungal, invertebrate, small mammal, reptile, frog and bird populations (Contos & Letnic, 2019; Moseby et al, 2009; Rees, Kingsford, & Letnic, 2019).…”

Section: Strategic Adaptive Management Planmentioning

confidence: 99%

Strategic adaptive management planning—Restoring a desert ecosystem by managing introduced species and native herbivores and reintroducing mammals

Kingsford

West

Pedler

et al. 2020

Conservat Sci and Prac

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Arid rangelands are degraded worldwide, suffering vegetation transformation, soil erosion, introductions, and extinctions. Wild deserts is restoring a desert ecosystem in Sturt National Park, New South Wales, Australia (35,000 ha), eradicating or controlling introduced animals, managing native herbivores, and reintroducing regionally extinct mammals. We describe a Strategic Adaptive Management Plan for restoration of this desert ecosystem, including a vision, model of ecosystem processes, stakeholder input, a hierarchy of objectives linked to triggers and their management actions, producing outcomes and outputs. Our management treatments included two "no restoration" areas and three "restoration" areas. The latter include two exclosures (each 2,000 ha), free of introduced animals (foxes, cats, rabbits), with previously abundant kangaroos removed and regionally extinct mammals to be reintroduced. The third management treatment is a Wild Training Zone (10,400 ha), with introduced animals and kangaroos managed at low levels, using innovative methods, improving survivorship and avoidance behavior of reintroduced mammals to introduced predators. These measures will allow populations of threatened animals to establish, initially in the exclosures, then the Wild Training Zone and potentially more widely. Our strategic adaptive management planning approach is generic and implementable for any natural resource management project, providing explicit steps and processes that track and report transparently on outcomes, fostering learning by doing.

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Top-down effects of a large mammalian carnivore in arid Australia extend to epigeic arthropod assemblages

Cited by 12 publications

References 37 publications

Terrestrial mesopredators did not increase after top-predator removal in a large-scale experimental test of mesopredator release theory

Terrestrial mesopredators did not increase after top-predator removal in a large-scale experimental test of mesopredator release theory

Spatial variability in the contribution of termites to the decay of plant detritus

Strategic adaptive management planning—Restoring a desert ecosystem by managing introduced species and native herbivores and reintroducing mammals

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