Australian ecologists have explained a clear example of how human enterprise depends on the population structure of an entire food chain in the ecosystem. Effects of the top predator affect all of the chain down to the shrubby plants and the grasses.
Encroachment by woody shrubs is a serious problem for livestock producers because the shrubs compete with the grasses for the limited resources that the livestock depend on in the southeastern Australian dry rangeland.
Where dingoes are common, so are large populations of rodents. The rodents eat seeds of the shrubs. This protects the grasses needed for the livestock. The rodents are sparse because the dingoes remove mid-sized predators such as feral cats and imported red foxes. These mid-sized predators would reduce the rodent populations if dingoes were not common and this is what happens where dingoes have been extirpated by humans and also where dingoes are kept out by the 5600 Km dingo fence across Australia.
Human impacts on the ecosystem are reflected in the removal of dingoes, the importation of red foxes, the introduction of feral cats, the desire for livestock production in semi-arid lands and our attempts to “manage” an ecosystem without understanding its functioning.
More information: Journal of Animal Ecology 2016; doi:10.11.111/1365-2656.12607