Wild pigs can be called anything you like: swine or boar, hogs or razorbacks. They are a highly destructive invasive species that is known for causing damage to native wildlife and agriculture.They are able to uproot soil on large scales, much like tractors ploughing fields. Today's research is the first to quantify the global impact of this phenomenon and the implications for carbon emissions.Our findings were astonishing. The cumulative area of soil that wild pigs have ripped up is similar to Taiwan. This results in 4.9 million tonnes of carbon dioxide being released each year, which is the equivalent of one million cars. These emissions are mainly from Oceania.The soil holds a large amount of carbon, so even a tiny fraction can have a significant impact on climate change.Problem with pigsAlthough wild pigs (Sus scrofa), are native to Europe and Asia, they now live on every continent, except Antarctica. This makes them one of the most invasive mammals on Earth. Australia is home to three million wild porcs.Wild pigs are responsible for destroying more than A$100million (US$74 Million) of Australian crops and pasture every year, and more that US$270million (A$366 Million) in 12 US states.In 54 countries, wild pigs are also known to be a threat to 672 species of vertebrate or plant species. These include threatened Australian tree frogs, ground frogs, and multiple orchid species.Their geographical range will expand over the next decades, which suggests that their threats to biodiversity and food security will increase. Let's now focus on their contribution towards global emissions.Their carbon footprintAlthough research in the past has shown that wild pigs could contribute to greenhouse gas emissions at a local level, it was only on a small scale.This study was done in the hardwood forests of Switzerland for three years. Researchers found that wild pigs cause soil carbon emissions to rise by approximately 23% each year.Similar results were found in a study at the Jigong Mountains National Nature Reserve, China. It showed that soil emissions rose by more than 70% annually in areas disturbed by wild porcs.We ran 10,000 simulations to determine the global impact of wild pig populations in non-native locations, including the Americas, Oceania and Africa.We calculated the soil that they would disturb by using a model from another study for each simulation. Finally, we used case studies from local communities to determine the maximum and minimum wild pig-driven carbon emission.We estimate that wild pigs will uproot approximately 36,214 to 123,517 square kilometers each year, or roughly equal to the size of Taiwan and England.Oceania is the region where most of the soil damage and associated emissions occurs. This is due to the large number of wild pigs in Oceania and the high carbon content of the soil.How does soil disturbance release carbon?Wild pigs dig through soil with their strong snouts in search of plant parts, such as roots and fungi. Ploughing disturbs soil to a depth of approximately five to fifteen centimetres. This is about the same depth as farmers using crop tilling.Wild pigs can decimate small areas of land quickly because they are social animals and will often eat in large groups. They are a formidable opponent to soil organic carbon.The soil's organic carbon is simply the ratio of organic matter in the soil (such fungi, animal manure, root growth, and leaf litter) to organic matter out (such decomposition, respiration, and erosion). This is a sign of soil health.Carbon is released into the atmosphere when soils are disturbed by ploughing, animal burrowing, or uprooting.This is because soil exposed to oxygen through digging can promote the rapid growth and development of microbes. These microbes are then able to break down organic matter that contains carbon.Cunning and toughDue to their cunning nature, rapid breeding rates, and tough nature, wild pig control can be extremely difficult and expensive.Wild pigs, for example, have been known not to trap if they were previously caught. They are also skilled at manipulating their behavior to avoid hunters.Coordinated hunting events are used to control wild pig populations in Australia. Others include installing fences and traps to stop wild pig expansion or aerial control programs.These control methods can also produce significant carbon emissions. For example, helicopters are used for aerial control. These costs may be outweighed by the long-term benefits to wild pigs.It is not easy to work towards reducing global emissions. Our study is yet another tool in our toolbox for assessing the threat posed by this widely invasive species.This article was first published by The Conversation. You can read the original article.
