Link between feral horses and peatland carbon emissions studied

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Feral horse populations in the Australian Alps pose a threat to Sphagnum peatlands, according to recent
research. 

Peatlands serve as highly efficient natural carbon capture and storage ecosystems, surpassing the capabilities of rainforests. Despite covering just 3% of the Earth's land surface, they house approximately 30% of the world's soil carbon—twice the amount stored in all the planet's forests combined.

 

In the Australian Alps, peatlands are characterised by carbon-rich peat soil within mossy wetlands formed from partially decomposed plants in swampy conditions. These ecosystems excel in capturing carbon in live moss layers and storing it in soils for long periods, sometimes spanning thousands of years.

 

However, when peatlands, particularly those rich in Sphagnum moss like those in the Australian Alps, are degraded, they can switch from carbon sinks to carbon sources. The disturbance may release more carbon into the atmosphere as greenhouse gases than they capture.

 

The precise connection between this degradation and the carbon cycling of peatlands remains unclear. A study conducted by researchers from RMIT University in Australia sought to address this knowledge gap. A full report of the work is published in the Journal of Environmental Management.

 

Sarah Treby, and Samantha P. Grover conducted a multi-site comparison of CO2 and methane fluxes from Australian peatlands. The investigation focused on 12 alpine and subalpine Sphagnum moss-dominated bogs in Kosciuszko National Park, New South Wales. Over a seven-day period in March 2022, the researchers sampled seven sites with feral horses present and five without.

 

Using a portable greenhouse gas analyser and transparent chambers to measure peatland carbon dioxide (CO2) emissions, they revealed a correlation between the presence of feral horses and increased carbon loss.

 

Their findings showed significantly higher emissions at sites degraded by feral horses compared to horse-free sites.

 

Sites with horses exhibited carbon emissions to the atmosphere, while sites without horses showed carbon removal from the atmosphere. Notably, net carbon emission was 91% higher in bare soil areas than in Sphagnum-covered areas.

 

Sites with feral horses also displayed higher soil bulk density, temperature, electrical conductivity (EC), and water pH, EC, and turbidity compared to sites without horses. 

 

The findings suggested that excluding feral horses from peatland areas could mitigate carbon loss to the atmosphere and improve overall site condition, peat soil quality, and water quality.

 

 

For more details, see: 

Carbon emissions from Australian Sphagnum peatlands increase with feral horse (Equus caballus) presence

Sarah Treby, Samantha P. Grover

Journal of Environmental Management (2023) Vol 347, 119034

https://doi.org/10.1016/j.jenvman.2023.119034