The Modern Equine Vet
January 2024
Vol 14 Issue 1 2024
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News Notes

Feral Horses’ Effect on Climate

By Sarah Gates

One might think of a feral horse as being somewhat carbon neutral, but a new study found carbon emissions from Australian alpine peatlands to be much higher in areas disturbed by feral horses.

Peatlands are incredibly effective at capturing carbon. While peatlands only cover up to 3% of the Earth’s land surface, they store an estimated 30% of the world’s soil carbon. This is twice the amount of carbon stored in every forest on the planet.

Protecting these environments is an important step toward addressing global warming, according to Sarah Treby, PhD, an environmental scientist at RMIT University, in Australia.

The researchers measured peatland CO2 emissions using a portable greenhouse gas analyzer, and found they were significantly higher at sites degraded by feral horses compared with sites where horses were not present. They looked at 12 alpine and subalpine Sphagnum moss-dominated bogs in Kosciuszko National Park, which were sampled over a 7-day period in March 2022—7 sites with feral horses present and 5 without. Data collected from sites with and without feral horses showed lowered water and soil quality where feral horses were present.

Horses also cause loss of soil carbon through waterways, known as fluvial carbon loss. Hard horse hooves trample and erode soils, which can end up in creeks and rivers, instead of in the peatland. This carbon is then transported downstream and, ultimately, released as carbon dioxide.

Degraded peatlands, such as those trampled by horses, can release large stores of carbon.

“The evidence suggests the damage resulting from horse grazing and trampling could have negative consequences for the long-term carbon storage of affected peatlands,” Dr. Treby said.

Horses were introduced to Australia in 1788 with the arrival of the first Europeans. Today, about 400,000 feral horses roam the country, according to the Invasive Species Council—more than any other country, with more than 18,000 in the Kozciuszko alone.

Co-author and soil scientist, Samantha Grover, PhD, explained these non-native feral horses are a destructive pest in the uniquely vulnerable Australian ecosystems.

Alpine and subalpine Sphagnum peatlands are listed as endangered and listed under the Environment Protection and Biodiversity Conservation Act 1999, due to their restricted geographic distribution, biodiversity declines and challenges in their restoration and regeneration.

Pest population management is carried out routinely in Australia for large hooved animals, including deer, pigs, goats, camels and water buffalo. Feral horse population management has been undertaken in many places around the country with a goal of reducing the population to 3,000 by 2027. However, in some areas, control methods that include culling have been controversial, constraining management programs.

“Our research on these peatlands in the Victorian Alps has shown that, in good condition, they can be strong carbon sinks, removing carbon dioxide from the atmosphere every year,” Dr. Grover said.

Australia’s peatlands also provide critical habitat and resources for rare and unique species, as well as water for hydroelectricity, drinking and irrigation. MeV

For more information:
Original story appeared on the RMIT website. Content was edited for style and length.
Treby S, Grover SP. Carbon emissions from Australian Sphagnum peatlands increase with feral horse (Equus caballus) presence. J Environ Manage. 2023;347:119034 doi: 10.1016/j.jenvman.2023.119034


Collapsed stream bank in Kosciuszko National Park shows damage caused by wild horses.
Credit: DPE