A new study examines the impact of horses on peatlands and their carbon storage potential
A new study by researchers at RMIT University, Royal Melbourne Institute of Technology, has found that carbon emissions from Australian alpine peatlands to be much higher in areas disturbed by feral horses.
The paper, "Carbon emissions from Australian Sphagnum peatlands increase with feral horse (Equus caballus) presence," was published in the Journal of Environmental Management.
Peatlands in the Australian Alps are a type of mossy wetland characterized by carbon-rich peat soil, formed in the same way as peatland areas in the UK’s uplands.
These ecosystems are incredibly effective at capturing carbon in the live moss layer then storing it in the soils below, and while peatlands only cover up to 3% of the Earth's land surface, they store an estimated 30% of the world's soil carbon.
Horses were introduced to Australia in 1788 and the country now Australia has approximately 400,000 feral horses. More than 18,000 of those are found in Kosciuszko National Park, where the study was carried out.
Data collected from sites with and without feral horses showed lowered water and soil quality where feral horses were present. The research suggests that horses also cause significant loss of soil carbon through waterways. Their hard horse hooves also trample and erode soils.
In the UK, the issue of peatland degradation through overgrazing is one that is frequently discussed, and in many cases, it is sheep and deer which are demonised.
Landowners such as the National Trust, the RSPB and NatureScot have been trying to address this perceived threat; culling the deer numbers down drastically, and often removing crofters and their livestock, who in many cases have worked the land for hundreds of year.
In their place, it has become fashionable to introduce a handful of ponies for the purpose of ‘conservation grazing’. In some cases they use native breeds, such as Exmoor ponies. In others, they have brought in animals from abroad, such as Konik ponies from Poland. At Wicken Fen in Cambridgeshire, which the National Trust describe as “one of Europe’s most important wetlands”, Konik ponies were introduced to help ‘make space for nature’. In Scotland, the RSPB use Koniks at RSPB Loch of Strathbeg and Insh Marshes sites, while at their Geltsdale site, they have Exmoor ponies, which they describe as ‘a great natural controller of bracken’.
But the recent study from Australia must surely be a cause for concern among those who have removed certain herbivores from these delicate sites, only to replace them with equine species.