Lumpy strangers: In addition to damage to nature, the wild boars, which are distributed worldwide by humans, also contribute significantly to climate change, a study shows. Through their burrowing activity, they cause a carbon dioxide release from the ground in their new areas of distribution, which corresponds to that of over a million cars, according to the model calculations. The further advance of the wild boar should therefore be curbed from an ecological and climatic point of view, say the scientists.
Once they were only at home in Europe and Asia – but then humans gave the wild boar (Sus scrofa) a global career: The animals were settled as hunting game in North and South America as well as in Australia and on many islands. There the adaptable omnivores thrived and spread. In some regions they are still on the rise. So far, the main focus has been on the associated damage to nature: wild boars threaten many animal and plant species and can thus destabilize the ecological equilibrium in their non-traditional habitats.
CO2 released by rummaging
In addition, it is already known that their burrowing activity can accelerate erosion processes and contribute to an increased breakdown of biomass in the soil. “Wild boars foraging for food are similar to tractors plowing through fields and turning the ground,” says Christopher O’Bryan of the University of Queensland in Brisbane. “When soils are churned up by humans or, as in this case, wildlife, carbon is released into the atmosphere. Since the soil contains almost three times as much carbon as the atmosphere, even a small part of the carbon released from the soil has the potential to accelerate climate change, ”explains the scientist.
Against this background, he and his colleagues have now investigated the question of what amounts of greenhouse gas are released by wild boars in the areas where they are not originally native. As a basis for their model calculations, they used earlier assessments of how much carbon dioxide can be released from the soil by the activities of wild boars. They linked this data with information on the distribution of the animals and estimates of population densities.
Animal contribution – caused by humans
The model calculations show that wild boars could be burrowing in their non-original areas of distribution over an area of possibly up to 124,000 square kilometers. As a mean guide value for the associated emissions, the scientists come to 4.9 million tons of carbon dioxide per year. To illustrate the importance of this amount, compare: The amount of greenhouse gas released worldwide by invasive wild boars is roughly equivalent to the annual emissions from 1.1 million cars.
As O’Bryan and his colleagues emphasize, they want to use their calculation results to show the problematic potential in a more fundamental way. Because these values have so far only been rough estimates, as the data bases are associated with a great uncertainty factor. The nature of the soils and the associated potential for carbon dioxide release is unclear in many regions. The same applies to the population densities of wild boars in their non-traditional areas of distribution. The researchers say that further investigations should now provide more clarity, especially with regard to this aspect.
“Invasive species like the wild boar are a man-made problem, so we need to be aware of and take responsibility for their environmental impact,” said University of Canterbury co-author Nicholas Patton. This also implies measures to curb the further spread so that the animal carbon footprint does not keep growing. Patton admits that controlling wild boar populations is difficult. However, given their potential threat to both ecosystems and the climate, intervention seems appropriate: “If invasive wild boars are allowed to spread into areas with abundant soil carbon, the risk of increased greenhouse gas emissions in the future may increase,” said Patton.
Source: University of Queensland, Article: Global Change Biology, doi: 10.1111 / gcb.15769