(Phys.org) —University of Auckland research revealing the extent to which feral pigs can disturb forest vegetation and soils has led to a call for the animals to be controlled as a pest in areas of high ecological value.
"Feral pigs are seen as an important hunting resource in New Zealand and I'm by no means suggesting that they should be controlled country-wide," says lead author Dr Cheryl Krull who did the research as part of her PhD.
"But in areas of high conservation value, we may need to view them in a different light – as a conservation pest rather than a resource – and look at methods to control or eradicate them locally to help the ecosystem to recover."
Feral pigs are known to physically change their environment by rooting for food and damaging the surrounding vegetation and forest floor, but the impact of feral pig ground disturbance had never before been studied in New Zealand.
"We found that feral pig ground disturbance resulted in a reduction in the diversity of seedlings and saplings in the forest, a dramatic reduction in leaf cover on the forest floor, and altered availability of nitrates (important nutrients for plants) in the soil," Cheryl says. Over time, it is likely that this would produce a change in the composition of the forest.
The authors concluded that feral pigs could have a significant impact on the entire forest ecosystem, especially since New Zealand species evolved in the absence of hooved animals capable of causing such damage.
The research was conducted in the Waitakere ranges as part of a study funded by Auckland Council Biosecurity. Dr Krull says the impact may be even greater in other parts of the country, with more delicate ground-level biology, such as alpine ecosystems with slower plant recovery rates.
The work has been published in the latest issue of Biological Invasions.
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