饥饿的野猪正在恶化气候变化

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没有生态帝国主义的经纪人比野猪更凶猛。如果欧洲人入侵澳大利亚,他们的猪也是他们的猪,其中许多人逃到了乡村肆虐。野兽穿过原生植物和动物,他们传播疾病,他们破坏了作物,他们在醒来时重建了整个生态系统。他们不是那么多害虫,因为它们是混乱所体现的。

现在加入气候变化对野猪的毁灭的reésumé。

这是另一个越来越令人担忧的难题,展示了对土地的修改有何改进 - 在这种情况下,无意中加剧了气候变化。

没有生态帝国主义的经纪人比野猪更凶猛。如果欧洲人入侵澳大利亚,他们的猪也是他们的猪,其中许多人逃到了乡村肆虐。野兽穿过原生植物和动物,他们传播疾病,他们破坏了作物,他们在醒来时重建了整个生态系统。他们不是那么多害虫,因为它们是混乱所体现的。

现在加入气候变化对野猪的毁灭的reésumé。在他们从不结束的食物中寻找食物,猪通过土壤根,搅拌像农民一样的污垢。科学家们已经在一定程度上知道,这释放了锁定在土壤中的碳,但澳大利亚,新西兰和美国现在已经计算了全世界可能令人不安的土壤野猪的研究人员。当作者结束时,他们每年生产的二氧化碳排放量,等于超过一百万辆汽车。

这是另一个越来越令人担忧的难题,展示了对土地的修改有何改进 - 在这种情况下,无意中加剧了气候变化。 “随时扰乱土壤,你是造成排放的,”昆士兰生态学家克里斯托弗·奥布兰大学,领导作者介绍了全球变革生物学杂志研究的新论文。 “例如,当您直到农业土壤时,或者您拥有广泛的土地利用变化城市化,森林损失。”

研究人员知道,鉴于他们对整个景观的统治,猪不得不使事情变得更糟,但没有人在全世界建模。 “我们开始意识到全球规模的巨大差距看这个问题,”O'Bryan补充道。

研究人员通过汇总以前的几个模型和数据来源来降落了他们的排放估计。例如,一个作者有一个模型,映射了世界各地的野猪人口。另一个曾在澳大利亚研究过野猪,并有关于物种扰乱土壤的数据。然后,研究人员在瑞士和中国创造的野生猪而在那里的碳排放中取出了估计。


这种拼凑而成的固有的不确定性。例如,没有模型可以确切地放下多少猪在给定时刻的给定位置。此外,当它们受到干扰时,不同种类的土壤发出更多的碳。一种像泥炭组成的材料,如没有完全分解的死亡植物物质 - 基本上浓缩碳,所以它比其他土壤更多地放弃。碳损失的量也取决于土壤的微生物组 - 在该植物材料上饲喂的细菌和真菌。

鉴于这种广泛的变量,研究人员模拟了10,000个潜在的全球野生猪密度地图,不包括欧洲和亚洲各地的动物的本地范围。 (换句话说,它们仅在猪是侵入性物种的地方建模。)对于这些模拟中的每一个,它们根据先前研究的数据随机分配猪诱导的土壤碳排放量。这允许它们将变量与数千种方式组合起来:这里有多少只猪在给定区域,这是他们打扰的土地有多少,这里是由此产生的排放。从这些尝试中,他们能够产生平均排放估计。

他们的模特表明,全球侵入性野猪根深得通过14,000到48,000平方英里的土地。但他们并没有均匀地遍布全球。虽然大洋洲 - 包括澳大利亚和波利尼西亚岛屿的地区 - 占世界土地面积的小数,它有很多猪。与此同时,热带地区是世界上大部分世界的泥炭所在的家园。 “在大洋洲的热带北部昆士兰州的某些部分,例如 - 这是大量的碳储存,”O'Bryan说。两者的结合意味着,根据团队的模型,大洋洲占通过生根野猪驱动的全球排放总量的60%。

他们认为,这一估计实际上是保守的。这是因为他们没有从农业土地上建模排放,这是巨大的,并且已知哪些野猪被掠夺免费食物。他们认为,技术上,这片土地已经受到干扰并发出二氧化碳,因此他们不想算两次。此外,研究人员仅估计野生猪现在可能在哪里,而不是他们很快就会在哪里。 “这种害虫正在扩大,他们可能会潜在地扩展到具有高碳股的地区,”奥巴克兰说。

研究有助于进一步量化地球上的迅速变化的碳循环(及其侵入性)物种)大大改变了土地本身。 “这篇论文带来的是,土壤科学家已知一段时间是一段时间 - 生物风相可以在土壤排放和土壤呼吸中发挥这种真正的关键作用,”佛罗里达州计算生物园化化学凯瑟大学说道,他不是参与研究。 “你也看到与蚯蚓运动相似的效果 - 任何种类的洞穴动物都越来越多的土壤结构。”

但是有一个关键的区别:本地动物正在为古老的碳循环作出贡献,他们发挥着长期作用。像野猪这样的侵入性威胁正在通过历史栖息地以外的碳富含土壤撕裂。 “骚乱是生态系统函数和碳平衡的一个组成部分,但我从来没有考虑过(30到50)野生猪可以做的伤害,”将生物园艺富裕的锥形写,他研究碳循环但没有参与这项研究,在电子邮件到有线。

现在的问题是如何处理野猪。他们很顽强,他们疯狂地疯狂,他们像贪婪一样贪婪,猪。消除它们可能非常困难。 2005年,为了摆脱Swine on Santa Cruz Island,在加利福尼亚州的海岸,直升机的Sharpshooters不得不逐一挑选5,000。花了14个月,造成500万美元。 (这是一个岛屿,猪被水包围在哪里。 ,你的问题将成为我的问题。

此外,大多数类型的根除努力也产生碳。 “如果我们进入直升机,我们去射击猪,或者我们设置陷阱,我们建造围栏,导致排放,”O'Bryan说。 “所以我们必须考虑这些权衡。”


英文译文:

There is no agent of ecological imperialism more ferocious than the wild pig. Wherever Europeans invaded, from the Americas to Australia, so did their pigs, many of which escaped into the countryside to wreak havoc. The beasts tear through native plants and animals, they spread disease, they destroy crops, and they reconstruct whole ecosystems in their wake. They’re not so much pests as they are chaos embodied.

Now add climate change to the wild pig’s résumé of destruction. In their never-ending search for food, the pigs root through soils, churning the dirt like a farmer tills fields. Scientists already knew, to some extent, that this releases the carbon that’s locked in the soil, but researchers in Australia, New Zealand, and the US have now calculated how much soil wild pigs may be disturbing worldwide. The carbon dioxide emissions that they produce annually, the authors concluded, equal that of more than a million cars.

It’s yet another piece of an increasingly worrisome puzzle, showing how modification of the land has—in this case, inadvertently—exacerbated climate change. “Anytime you disturb soil, you're causing emissions,” says University of Queensland ecologist Christopher O’Bryan, lead author on a new paper describing the research in the journal Global Change Biology. “When you till soil for agriculture, for example, or you have widespread land-use change—urbanization, forest loss.”

Given their domination of whole landscapes, pigs had to be making things worse, the researchers knew, but no one had modeled it worldwide. “We started to realize there's a big gap at the global scale looking at this question,” O’Bryan adds.

The researchers landed on their emissions estimate by aggregating several previous models and sources of data. For instance, one author had a model that mapped the populations of wild pigs around the world. Another had studied wild pigs in Australia, and had data on how much the species disturbs soils. The researchers then pulled in estimates done in Switzerland and China of the carbon emissions created by wild pigs rooting around there.

This patchwork creates inherent uncertainties. No model can pin down exactly how many pigs are in a given place at a given moment, for example. Also, different kinds of soils emit more carbon when they’re disturbed. A material like peat—made up of dead plant matter that hasn’t entirely decomposed—is essentially concentrated carbon, so it has more to give up than other soils. The amount of carbon loss also depends on the microbiome of the soil—the bacteria and fungi that feed on that plant material.

Given this wide range of variables, the researchers simulated 10,000 maps of potential global wild pig densities, excluding the animal’s native ranges across parts of Europe and Asia. (In other words, they only modeled the places where the pigs are an invasive species.) For each of these simulations, they randomly assigned values of pig-induced soil carbon emissions based on data from those previous studies. This allowed them to combine the variables in thousands of ways: Here’s how many pigs might be in a given area, here’s how much land they’d disturb, and here are the resulting emissions. From these thousands of attempts, they were able to generate average emissions estimates.

Their model showed that, worldwide, invasive wild pigs are rooting through somewhere between 14,000 and 48,000 square miles of land. But they’re not spread out evenly around the globe. While Oceania—the region that includes Australia and the islands of Polynesia—accounts for a tiny fraction of the world’s land surface, it has a huge number of pigs. At the same time, the tropics are home to much of the world’s peat. “In certain parts of Oceania—like tropical Northern Queensland, for example—there's this substantial amount of carbon stores,” says O’Bryan. The combination of the two means that, according to the team’s model, Oceania accounts for 60 percent of total global emissions driven by rooting wild pigs. 

This estimate, they think, is actually pretty conservative. That’s because they didn’t model emissions from agricultural lands, which are vast, and which wild pigs are known to plunder for free food. They figured that, technically, this land is already disturbed and emitting carbon dioxide, so they didn’t want to count it twice. Additionally, the researchers only estimated where the wild pigs may be now, not where they could be soon. “This pest is expanding, and they could be potentially expanding into areas with high carbon stocks,” says O’Bryan.

The research helps further quantify the rapidly changing carbon cycle on Earth, as humans (and their invasive species) dramatically transform the land itself. “What this paper brings to the fore is something that soil scientists have known for a while—that bioturbation can play this really key role in soil emissions and soil respiration,” says University of Florida computational biogeochemist Kathe Todd-Brown, who wasn’t involved in the research. “You also see similar effects with earthworm movement—any kind of burrowing animal that churns up the soil structure.”

But there’s a key distinction: Native animals are contributing to an ancient carbon cycle in which they play a long-standing role. Invasive menaces like wild pigs are tearing through carbon-rich soil outside their historical habitats. “Disturbance is an integral part of ecosystem function and carbon balance, but I'd never before considered the damage that (30 to 50) feral hogs could do,” writes biogeochemist Rich Conant, who studies the carbon cycle but wasn’t involved in the research, in an email to WIRED. 

The question now is what to do about the wild pigs. They are hardy as hell, they breed like crazy, and they’re as greedy as, well, pigs. Eradicating them can be extraordinarily difficult. In 2005, to get rid of swine on Santa Cruz Island, off the coast of California, sharpshooters in helicopters had to pick 5,000 of them off one by one. It took 14 months and cost $5 million. (And this was an island, where the pigs were surrounded by water.) Elsewhere people have found success trapping the animals, but to be truly effective this requires collaboration among local agencies: If I take care of my wild pigs and you don’t, your problem will become my problem.

Plus, most kinds of eradication efforts also produce carbon. “If we get in a helicopter and we go shoot pigs, or we set traps, we build fences, that causes emissions,” says O’Bryan. “So we have to account for these trade-offs.”


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