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ASU professor challenges conventional wisdom in invasion biology

ASU professor Matt Chew savors role as 'most hated man' in invasion biology.
ASU professor says everything in nature has been shaped by human activity.
February 28, 2017

Counterintuitive School of Life Sciences professor Matt Chew calls for emphasis on effect, function of tamarisk shrub

The license plate on Matt Chew’s Toyota Tacoma reads “Tamarix.”

It’s the scientific name for tamarisk, also called the saltcedar, a shrub introduced to the U.S. in the 1800s. Today, it’s choking off waterways throughout the Southwest.

People call the plant by many names. Few are fit for print. And the same can be said for Chew, an assistant research professor in the School of Life SciencesThe School of Life Sciences is an academic unit of the College of Liberal Arts and Sciences. at Arizona State University and the most hated man in invasion biology. It’s an appellation he savors.

Of all the names he’s been called, his favorite is “the invasive species gadfly.” His counterintuitive approach puts him at odds with those who would rank him somewhere between river scum and climate change deniers.

“I don't love tamarisk, either,” Chew said. “I just don't hate it. But I do find tamarisk — and people's feelings about it — very interesting.”

To most, the pink-flowered scrub brush embodies the worst problems associated with invasive species. Chew, however, is calling for more emphasis on understanding the effects and functions of the plant, and less emphasis on where it came from and when. Invasive species can create benefit as well as harm, Chew argues. A paper defending his views is due to be published soon in Trends in Ecology and Evolution.

Water managers, farmers and ranchers say tamarisk bushes suck up too water. Botanists say it kills every native plant around it. Environmentalists say it turns desert riparian areas into dry, salty basins. For rafters and kayakers, it turns riverbank campsites into impenetrable thickets and creates deadly hazards. People floating the Rio Grande have been sucked beneath matted tamarisk roots and pinned by the current.

The U.S. Department of Agriculture classifies tamarisk as an invasive plant. There are groups dedicated to removing it, a near-impossible task. Burning tamarisk makes it grow back faster. Cut it down, and it just grows back. Herbicides don’t work.

When national parks and other federal agencies responsible for public lands talk about restoring natural habitat, “what they’re talking about is a perpetual gardening project,” Chew said.

“They want it to look like it was before man came,” he said. “In some ways it’s misanthropic.”

Chew tries not to use the word “native” anymore.

“It doesn’t mean very much,” he said. “Everything has been brought in from somewhere else. Invasive biologists systematically exclude imported species from their classifications.”

One of Chew’s points is this: Which point in the past do you choose as the ideal Eden? Before Europeans came to the New World? Mesoamericans traded (non-native) red macaws with the Anasazi in present-day New Mexico. Tamarisk was introduced to New England sometime before 1818. So, is it the ideal native state of nature before 1818? Or before the tamarisk was widely planted out West in the 20th century? Or do you go back to North America before people, when wooly mammoths and giant sloths roamed the plains?

“Invasion” has also gone from the New World to the Old, as well. Raccoons in Europe aren’t native, nor are grey squirrels in the United Kingdom.

"Every organism now living occupies an environment shaped to some degree by human activity."

– Matt Chew, assistant research professor, School of Life Sciences 

“Invasion is a difficult metaphor, but it’s a compelling one,” Chew said. “You’ve got to take them on a case-by-case basis.”

When ecology emerged, society distinguished humans from nature. By the time ecology became a science, human affairs were regarded as an imposition on nature. Ecologists sought to study wild sites. By the time it was understood that the players and the stage were inseparably intertwined, few were (and are) unwilling to abandon the idea of “real” ecology where man’s hand is unseen.

In the case of tamarisk, it’s been vilified beyond rational thinking. In one of his papers, Chew notes that post-World War Two, the plant was described in similar terms to the Japanese a few years earlier. One suggestion at the time was to burn the plant out with flame throwers, a callback to the Pacific campaign.

“The history to date has been fostering fear and loathing whenever possible,” Chew said.

The problem is governmental, industry, and conservation groups use the widely available body of misinformation regarding tamarisk in preparing legislation, executive orders, management policies and plans, and promotional and educational materials, Chew said. Scientists, too, redisseminate outdated, inaccurate information in journal articles, further disconnecting science and management, he said.

But some scientists are becoming convinced that tamarisk is, as Chew says, “as much a ‘passenger’ of change as a ‘driver’ and has positive ecological values of its own.”

Trend lines are shifting from a “pest plant” eradication stance to systemic, process-based restoration.

Increasingly, scientists are recognizing that ecosystems are reorganizing around tamarisk, providing food and cover to species.

Chew teaches a field class called Novel Ecosystems. It is intended to challenge preconceptions and received wisdom about the environment. The class goes to places you’ll never find on a postcard: to effluent-dominated wetlands, farm fields, newer and older commercial and residential areas, fake lakes and vacant lots.

“Among all this contention, one fact remains: Every organism now living occupies an environment shaped to some degree by human activity,” the class syllabus reads. “The conceptual separation between history and natural history is undeniably fictional. We would be hard pressed to demonstrate that individuals of any other species know or care. Real organisms must live and real ecological relationships must occur in the real world, and we will look for them there.”

On a recent balmy day, the class meets at the Rio Salado Habitat Restoration Area in Phoenix. Planes roar overhead. Rabbits hop along dirt paths. Salt River Project is doing a release from the Verde River, so the normally modest channel is bank-to-bank.

“This is very artificial,” Chew told his students. “At one point they basically killed everything down here to rechannel it.”

Underneath the Seventh Street bridge, Chew points out a white lead tree, a Central American tree spread around the world for cattle fodder. They’re found in vacant lots all over Phoenix. There is also an Australian acacia, papyrus (from North Africa and the Middle East, used as paper by the ancient Egyptians), and a eucalyptus tree (also from Australia).

“It’s getting kind of cosmopolitan down here,” Chew said.


Top photo: Assistant research professor Matt Chew checks the early buds on a willow branch at the Rio Salado Habitat Restoration Project under Seventh Street in Phoenix. Chew guides his dozen BIO494 students through the Rio Salado area helping them identify native and invasive flora, mammals and birds in the area. After rainstorms, biological debris, including seeds, come through the flood control zone from residential and commercial landscapes. The seeds — papyrus, willow, acacia, fan palms, etc. — then take root in the damp soil of the riverbed. Photo by Charlie Leight/ASU Now

Scott Seckel

Reporter , ASU Now


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Author Jeffrey Toobin says far-right shift likely for Supreme Court

Author Jeffrey Toobin: Sandra Day O’Connor ‘giant figure in history of law.‘
March 1, 2017

Legal analyst for CNN and staff writer for The New Yorker delivers John J. Rhodes Lecture in Public Policy, presented by Barrett, the Honors College

The Supreme Court is just as politicized as Congress, and will likely begin to reflect the recent far-right shift of the Republican Party, according to legal analyst Jeffrey Toobin.

“It is often said, it is often hoped, it is sometimes believed that the Supreme Court is a refuge from the partisan divisions in Congress. But I’m here to tell you it’s not true,” said Toobin, who has written two books on the top court.

“It’s a deeply partisan institution, and it’s divided along the same lines as the rest of Washington, Democrats against Republicans, but very evenly so,” he said.

Toobin, lawyer, author, legal analyst for CNN and staff writer for The New Yorker, addressed about 600 people at Tempe Center for the Arts on Tuesday night. His talk, titled “The Supreme Court in the Post-Obama Age,” was the annual John J. Rhodes Lecture in Public Policy, presented by Barrett, the Honors College at Arizona State University.

Toobin traced the political trajectory of the court, starting from the very liberal 1960s, when the justices overturned the law against interracial marriage and upheld protections for the press. He noted that President Richard Nixon appointed four justices in only five years as president, and even though he was Republican, the court remained liberal into the 1970s, overturning the ban on abortion and the death penalty.

“That’s because the Republican Party of the ’70s was unrecognizable from the Republican Party of today,” said Toobin, who wrote “The Nine: Inside the Secret World of the Supreme Court” in 2007 and “The Oath: The Obama White House and the Supreme Court” in 2012.

That began to change with President Ronald Reagan in the 1980s, who pushed for a more conservative judiciary, and who also appointed Sandra Day O’Connor to the court.

“If there has been a greater Arizonan than Sandra Day O’Connor, I don’t know who it would be,” Toobin said. “She is just a giant figure in the history of the law. But she was also not a religious conservative or a social conservative. She was a Westerner, a libertarian style conservative.

“She was one of the votes that saved Roe v. Wade.”

Toobin noted that his lecture was named for John J. Rhodes, a moderate conservative who recognized the value of government. Rhodes, an Arizona Republican who served in Congress from 1953 to 1983, was the driving force behind congressional authorization of the Central Arizona Project, which provides water from the Colorado River to Arizona.

“He embodied a different kind of Republican Party than the one we have today,” Toobin said. “He was a proud conservative, who believed in small government and low taxes.”

He said that the Central Arizona Project was a “big government” project that showed how government could work.

Toobin said that when he wrote his books about the justices, he hoped to uncover personal animosities among the members.

“Somewhat to my disappointment as a journalist but to my satisfaction as a citizen, I learned that was not the case,” he said, noting that the court under Chief Justice John Roberts is genial.

Toobin said that the Supreme Court of more recent years was more conservative with two exceptions — upholding the tenets of Obamacare and affirming same-sex marriage.

When Justice Antonin Scalia died in February 2016, President Barack Obama had 11 months left in his term.

“Mitch McConnell, the majority leader in the Senate, said within an hour of Justice Scalia’s death that there would be no hearing or vote on a successor while Obama was in office.

“And it worked to perfection. The blockade held.”

There was no vote on Obama’s nominee, Merrick Garland, leaving the current court with eight justices, evenly divided between Republicans and Democrats. Trump has nominated Neil Gorsuch, whom Toobin said is brilliant and accomplished.

“He’s very conservative when it comes to the rights of African-Americans, gay rights, voting rights.

“We are in a moment where the conservative Republicans are in the ascendancy, and they are getting the Supreme Court they want.”


Top photo by Charlie Leight/ASU Now

Mary Beth Faller

reporter , ASU Now