July 15, 2024
Feral Horses

Impact of Feral Horses on Carbon Emissions From Peatlands

A new study conducted by RMIT University has revealed that carbon emissions from Australian alpine peatlands are significantly higher in areas disturbed by feral horses. Peatlands in the Australian Alps are wetland ecosystems characterized by mossy soil rich in carbon. These peatlands are remarkably efficient at capturing carbon from the atmosphere and storing it in the soil for thousands of years. Although peatlands cover only 3% of the Earth’s land surface, they store around 30% of the global soil carbon, which is twice the amount stored in all the world’s forests. Protecting these environments is crucial in combating global climate change.

The study, led by Dr. Sarah Treby, a postdoctoral researcher, focused on the impact of feral horses in the Kosciuszko National Park in New South Wales. It is the first research to explore how the degradation caused by these horses affects carbon cycling in Australian alpine and subalpine peatlands dominated by Sphagnum moss. The preliminary study measured carbon dioxide (CO2) emissions from the peatlands using a portable greenhouse gas analyzer and transparent chambers. The researchers found significantly higher emissions at sites degraded by feral horses compared to sites where horses were absent.

Previous studies have shown that feral horses contribute to biodiversity loss and environmental degradation. Dr. Treby’s study also revealed differences in overall site condition, as well as soil and water quality, between areas with and without feral horses. The researchers ruled out the presence of other large feral herbivores, such as deer or pigs, as a contributing factor to the differences observed. The evidence suggests that the grazing and trampling by horses could have long-term negative consequences for the carbon storage capacity of affected peatlands.

Horses were introduced to Australia in 1788 and have since become a major environmental concern. The country currently has an estimated 400,000 feral horses, more than any other country. Kosciuszko National Park alone is home to over 18,000 feral horses, according to the NSW National Parks and Wildlife Service. Dr. Samantha Grover, a soil scientist and co-author of the study, explains that feral horses are destructive pests in the fragile Australian ecosystem. Unlike native wildlife, horses and other large grazing animals have hard hooves that can cause extensive damage to the soil through trampling and compaction. This leads to erosion, reduced water infiltration, and loss of topsoil, which is rich in carbon and fertility.

The data collected from sites with and without feral horses showed lower water and soil quality in the presence of these animals. The study also suggests that horses contribute to significant loss of soil carbon through waterways, known as fluvial carbon loss. The trampling and erosion caused by hard hooves result in the displacement of carbon-rich soil, which can be transported downstream and released as carbon dioxide. Peatlands, when undisturbed, are among the most effective natural carbon capturing and storing ecosystems, surpassing even rainforests in this regard. However, degraded peatlands, such as those affected by horse activity, can become carbon sources, releasing more carbon back into the atmosphere than they capture.

The research, which was supported by Parks Victoria’s Research Partners Program, represents the first multi-site comparison of CO2 and methane fluxes from Australian alpine and subalpine peatlands dominated by Sphagnum moss. The aim of the study was to provide an initial understanding of carbon cycling in these ecosystems. The researchers now plan to expand the study to cover the entire Australian Alps region and examine the impact of feral herbivores on peatland carbon cycling over a longer time period. This comprehensive research will contribute valuable insights to mitigate the detrimental effects of feral horses on these important carbon sink ecosystems across Australia.

1. Source: Coherent Market Insights, Public sources, Desk research
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