Hungry wild boars are exacerbating climate change


No proxy Ecological imperialism More ferocious than wild boar. Wherever the Europeans invaded, from America to Australia, their pigs also invaded, many of them fled to the countryside to wreak havoc. These beasts tear up native plants and animals, spread diseases, destroy crops, and rebuild entire ecosystems behind them. They are not so much pests as they are the incarnation of chaos.

Now add climate change to the wild boar’s destruction resume. In their endless search for food, the pigs take root in the soil and stir the soil like a peasant farming. Scientists already know that, to some extent, this releases carbon locked in the soil, but researchers in Australia, New Zealand, and the United States have now calculated how many soil wild boars around the world may disturb the soil. The authors concluded that their annual carbon dioxide emissions are equivalent to the emissions of more than 1 million cars.

This is another part of an increasingly worrying puzzle, showing how the land was modified-in this case, inadvertently-Exacerbated climate change“Anytime the soil is disturbed, it will cause emissions,” said Christopher O’Bryan, an ecologist at the University of Queensland and the lead author of a study. New article Describe the research in the journal Global Change Biology. “For example, when you cultivate soil for agriculture, or you have extensive land use changes-urbanization, forest loss.”

Given their domination over the entire landscape, the pigs Have To make matters worse, researchers know it, but no one has modeled it worldwide. “We are beginning to realize that there is a big gap globally on this issue,” O’Brien added.

Researchers aggregated several previous models and data sources to derive their emissions estimates. For example, an author has a model to map the population of wild boars around the world. Another studied wild boars in Australia and obtained data on the extent to which the species damages the soil. The researchers then estimated carbon emissions from wild boars rooted in Switzerland and China.

This patchwork creates inherent uncertainty. For example, no model can accurately determine how many pigs are in a given location at a given moment. In addition, different types of soil emit more carbon when disturbed.Materials like peat-composed of dead plant matter that has not yet been completely decomposed-are essentially Concentrated carbon, So it has more abandonment than other soils. The amount of carbon loss also depends on the soil microbiome-bacteria and fungi that feed on plant material.

Considering such a wide range of variables, the researchers simulated 10,000 potential global wild boar density maps, exclude The origin of this animal is distributed in parts of Europe and Asia. (In other words, they only simulated places where pigs are an invasive species.) For each of these simulations, they randomly assigned values ​​for soil carbon emissions caused by pigs based on data from previous studies. This allows them to combine variables in thousands of ways: this is how many pigs may be in a given area, this is how much land they will disrupt, and the resulting emissions. From these thousands of attempts, they were able to derive estimates of average emissions.

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Their model suggests that invading wild boars are taking root on 14,000 to 48,000 square miles of land worldwide. But they are not evenly distributed around the world. Although Oceania-including Australia and the Polynesian Islands-accounts for a small part of the world’s land area, it has a large number of pigs.At the same time, the tropics are Most of the peat in the world“In some parts of Oceania—such as northern Queensland—there are large amounts of carbon storage,” O’Brien said. The combination of the two means that, according to the team’s model, Oceania accounts for 60% of total global emissions, which is caused by rooting wild boars.

They believe that this estimate is actually quite conservative. That’s because they did not simulate the emissions from farmland, which is vast and wild boars looted for free food. They believe that, technically speaking, this land has been disturbed and emits carbon dioxide, so they do not want to double-count.In addition, the researchers only estimated where the wild boar might be right now, Not where they can go quickly“This pest is expanding, and they may expand to areas with high carbon stocks,” O’Brien said.

The research helps to further quantify the fast-changing carbon cycle on the planet, because humans (and their invasive species) have greatly changed the land itself. Kathe Todd-Brown, a computational biogeochemist at the University of Florida, said: “This paper highlights what soil scientists have known for a long time-that bioturbation can play a really key role in soil emissions and soil respiration.” Participated in the research. “You will also see a similar effect of earthworm movement-any kind of burrowing animal that disturbs the structure of the soil.”


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