The work of two UNM faculty members may redefine the procedures and concept of environmental conservation by comparing changes that occurred after the last ice age to the changes we face today.
Felisa Smith, a biology professor, and Melissa Pardi, a biology doctoral candidate, have contributed to a series of research that addresses the environmental changes that occurred after the megafauna extinction of the Pleistocene epoch.
Smith's and Pardi’s research is comprised of computer models based on fossil distribution of Pleistocene predators in different environments and core samples which model the effects the Pleistocene extinction had on ecosystems.
“Most people assume that something goes extinct ... they don’t understand that this animal that’s gone extinct ... is embedded in a complex of interactions,” Smith said. “Of course it’s awful the animal goes extinct but what we’re interested in is all the interactions that it’s tied into.”
Smith said their megafauna extinction model is being used as a proxy to model ongoing biodiversity loss. Smith and Pardi relate the model, which has mammoths as major ecosystem engineers, to the mammoth’s closest living relative the elephant and other remaining megafauna such as giraffes and rhinos.
“Envision North America with a bunch of caterpillar tractors roaming around, now envision that you take them off the landscape and you can imagine that it’s changed the landscape dramatically,” Smith said. “The sheer weight of these large-bodied animals are going to have effects on the soil structure.”
In a recently published paper, Smith stated remaining megafauna had the same purpose as Pleistocene megafauna: as ecosystem engineers that alter environmental conditions by uprooting trees, altering soil composition, and adding methane to the atmosphere.
“The point is you have all these animals doing all these things in the ecosystems, and then they’re gone at a massive scale,” Pardi said.
Smith and Pardi said the prominent effects after the extinction were changes in vegetation, and a resulting change in predatory hierarchy in the absence of newly extinct apex predators.
“The animals we think of today as the top predators weren’t, they were the middle guys,” Smith said.
Smith said in the absence of apex predators like dire wolves and saber toothed cats, smaller predators like wolves and coyotes took the position of the extinct apex predators but they weren’t evolved for the position and lacked the efficiency of the previous predators.
“A wolf is not a dire wolf and a coyote is not a wolf,” Pardi said. “They’re not interchangeable with each other.”
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Smith said the event of lower predators taking higher food chain positions also occurred with smaller herbivores taking the position of megafauna. Replacing 2-ton megafauna with 500-kilogram cows does not retain current ecosystem functions.
“(With) the loss of the herbivores we got dramatic changes in vegetation, we had dramatic changes in climate, like water table levels,” Pardi said. “Scientists have been studying this topic for only 10 years...so we don’t know the full effects.”
One of the effects that Smith and Pardi discovered was the effect on atmospheric methane levels that megafauna had in the Pleistocene epoch, which Smith said was a significant amount.
“Today in North America, 35 percent of the methane that we produce comes from livestock.” Smith said. “Methane is a huge greenhouse gas and is probably the second most important in terms of climate forcing.”
Smith and Pardi’s paper says that methane production by herbivores scales allometrically with the body mass of herbivores, meaning that larger herbivores produced more methane. The extinction event, according to the paper, states that there was a large drop in atmospheric methane levels following the extinction.
Smith said that today’s levels of methane production is attributed to livestock, but in their findings in the Pleistocene era, most of the methane levels were produced by wildlife.
“(The Intergovernmental Panel on Climate Change) track livestock, but there’s this idea that wild animals somehow don’t count,” Pardi said. “It certainly counted during the Pleistocene.”
Smith said their findings may help the scientific community understand what could happen after the extinction of elephants and rhinos.
Recently Smith helped organize a conference in Oxford that had conservationists and paleontologists interacting on climate change for the first time.
“It was the first time that you had conservation biologists talking to paleontologists talking to people who want to do rewilding and other things,” Smith said. “People hadn’t gotten together and realized ‘wait a minute, this has happened before’.”
Pardi said current actions of killing wildlife could prove detrimental to current ecosystems due to a lack of biodiversity and species that are able to fill the position of higher extinct species.
“We see the extinction of the animal immediately but it might take years, decades, or hundreds of years to see the effects of those interactions,” Pardi said, “And at that point it’s too late to do anything about it.”
Pardi said while the effects of the Pleistocene extinction are available and are under research, that effects of what could happen after current megafauna extinction are still unknown.
Fin Martinez is a reporter for the Daily Lobo. He can be reached at news@dailylobo.com or on Twitter @FinMartinez
