Trade-offs: Exotic Invaders Are a Threat to Our Forests

Trade-offs: Exotic Invaders Are a Threat to Our Forests

A Customs and Border Patrol officer directs a truck carrying an offloaded shipping container to an inspection area at a port. Photo courtesy of CBP

Somewhere out there is a ship carrying, in one of its thousands of steel containers, a natural disaster. The ship could be an old rust bucket. Or a brand new, high-tech cargo vessel. It might be steaming toward our shores right now. Or it might not have even been built yet. But literally or figuratively, it is on the horizon.

Just what is this deadly cargo? Not high explosives or a dirty bomb, but an exotic forest pest or pathogen. It could be an innocent looking brown bug. Or a yellow one. Or black with yellow spots. Probably a beetle. Unless it’s a fungus. Or a tiny sapsucking bug. Or a virus. Whatever it is, it might very well wreak death and destruction on the already ravaged forests of North America, further diminishing our ecological heritage.

This doom-laden scenario is not a sweat-soaked nightmare from which we can wake up and go about our day, but a reality we must face. It has happened before. Too many times. It will happen again.

Lessons Learned

In 1904, the Bronx Zoo’s chief forester, Herman K. Merkel, noticed something disturbing: the American chestnut trees at the zoo were dying, their trunks marred by open wounds. He didn’t know it at the time, but he was looking at a disaster in the making.

The killer was a fungus that had hitchhiked to the U.S. on imported Japanese chestnut trees. The disease it caused became known as chestnut blight. Asian chestnuts had evolved a resistance to the blight; the American chestnut had none. The American chestnut was king of the forest – its nutritious nuts used by people and wildlife, its straight-grained, decay-resistant wood in demand for everything from framing timbers to furniture, shingles to piers.

But by the 1940s, virtually all the American chestnut trees in the eastern forests – some four billion of them – were dead, the species reduced to scattered survivors and stump sprouts that are doomed to die again and again. Most people alive today have never seen a mature American chestnut.

The chestnut blight is emblematic of what happens when a non-native disease or pest gets loose in a new environment, where no resistance or immunity has been built up, and there are no natural enemies to keep its population in check. It’s the forest’s equivalent of what happened to Native Americans when Europeans brought measles, influenza, and smallpox to the shores of the New World: a tragedy.

Trade-offs: Exotic Invaders Are a Threat to Our Forests Image Photo courtesy of CBP

Similar tales abound. Around the same time that chestnut blight made its way to North America, another devastating disease, white pine blister rust, was imported on European pine seedlings, requiring a massive government response. In 1930, Dutch elm disease was imported with a shipment of unpeeled veneer logs from Europe, and it wiped out America’s favorite street tree by the millions. Trees in their natural habitat, on rich soils in valley bottoms, have also disappeared. Then there’s beech bark disease, first noticed in the U.S. in Massachusetts in 1929. Butternut canker appeared in the middle of the twentieth century. Hemlock woolly adelgid, an aphid-like sucking insect, came from Japan to the East Coast in the mid-twentieth century and has devastated eastern hemlocks. The balsam woolly adelgid turned the Fraser firs on the slopes of the southern Appalachian Mountains into ash-colored sticks. And as the twentieth century turned into the twenty-first, a small, shiny green beetle from China was found in Detroit, Michigan, munching on ash trees. Called the emerald ash borer, it proceeded to kill millions of ash trees in two dozen U.S. states and two Canadian provinces and is still spreading.

The problem of imported tree-killing insects and diseases has been around for a long time. Unfortunately, despite the fact that we know how these tragedies generally play out, some experts say we haven’t taken all of the steps needed to curb the importations. The fight to prevent exotic forest pests from entering the U.S. – and from expanding their beachhead if they make it in – is underfunded and plagued by foot-dragging bureaucrats who don’t want to rile a pro-trade lobby that views anything that slows imports as bad. Perhaps worst of all, it lacks a constituency, an organized and vocal group of concerned citizens who are willing to press policymakers, including Congress, to take things seriously and move expeditiously to improve the nation’s defenses against forest and agricultural pests and diseases.

“This is the most severe and urgent threat to forest health . . . certainly in the eastern U.S., though I think you could make the argument for throughout the U.S. And it’s underappreciated,” said Gary Lovett, forest ecologist and senior scientist at the Cary Institute for Ecosystem Studies in New York.

There are other threats to the forest, of course, including native insects and pathogens, but “imported forest pests are the only type of forest disturbance that can wipe out whole species and sometimes whole genera in a matter of decades,” said Lovett. And, he noted, it’s costing homeowners millions in taxes to cut down trees and millions more in lost property value.

“It’s an awful situation right now, and it’s only going to get worse,” said Scott Schlarbaum, a professor of forest genetics at the University of Tennessee and the author, with Faith Thompson Campbell, of three landmark “Fading Forests” reports that look at the problem of exotic forest pests. Their latest report, Fading Forests III: America’s Forests – What Choice Will We Make?, came out in 2014.

Let’s put some numbers on “awful:” According to Fading Forests III, at least 30 new tree-killing insects and pathogens have been detected in the U.S. since the turn of the twenty-first century. That brings to 475 the number of known non-native forest pests and diseases in the country. New arrivals include polyphagous shot hole borer, which sounds ominously like something spawned at the foot of Mt. Doom; laurel wilt; the thousand cankers disease of black walnuts; and gold-spotted oak borer. Of the 475 here now, at least 62 are insects. Seventeen are pathogens that have been deemed “high impact,” with serious economic and ecological effects.

“Now there is an exotic pest threat to nearly every dominant tree species in the eastern deciduous broadleaf forest – a major landscape component in 20 states,” reported Fading Forests III.

Inspecting Imports

When it comes down to it, these pest and disease importations are all the result of trade.

No one brings in exotic tree-killing pests purposely. The pests stow away on goods bound for the U.S. Sometimes, as was the case with chestnut blight and white pine blister rust, they arrive on tree seedlings. Horticultural imports bound for the backyards and garden beds of suburban America are a major pathway for diseases and pests. Another vector is wooden packing material – the crates and pallets that hold goods for shipping.

And America imports a lot of stuff. To get an idea of the volume of global trade, just Google “tracking the seven seas.” The YouTube video by major ship tracking company FleetMon compresses a week’s worth of global shipping traffic into less than two minutes. Each ship is a dot of light, merging into veritable rivers as they move through geographical choke points such as the Suez Canal, the Strait of Gibraltar, and the Panama Canal, giving the impression of a freeway at rush hour.

Much of the world’s goods travel these days in shipping containers, those ubiquitous steel boxes, with some 20 million in use worldwide. In 2015, 7.9 million TEUs, or 20-foot equivalent units – the measuring standard for metal shipping containers – came into U.S. East Coast ports alone, up more than 12 percent from 2014, according to the shipping association BIMCO. The World Shipping Council put total 2014 U.S. imports at 19.6 million TEUs. By some estimates, inbound container traffic could top 20 million TEUs for 2016.

There are more and more container ships on the high seas, and they’re getting bigger. West Coast ports routinely handle ships bearing 14,000 containers; East Coast ports handle ships bearing 10,000, and are gearing up to handle bigger ships expected after a newly expanded Panama Canal opened in June.

The U.S. has 360 commercial ports – airports, border crossings, seaports – that handle upwards of $900 billion worth of goods a year, with the bulk of container shipping coming in through some two dozen seaports. The country’s busiest East Coast container port is the Port of New York and New Jersey. On the West Coast, the Port of Los Angeles and the Port of Long Beach handle huge volumes of containerized goods from China and the rest of Asia.

The gargantuan volume of international goods coming into the U.S. in shipping containers guarantees that only a tiny fraction can be checked for forest or agricultural pests or diseases.

It isn’t just the trade but where trade goods originate that poses a challenge. U.S. trade with China has risen dramatically over the last 30 years, to $482 billion in 2015. That means a huge increase in the possibility of importing Asian insects and diseases; it’s probably no coincidence that two of the most destructive imported forest pests in recent memory – the Asian longhorned beetle and the emerald ash borer – came from China.

Trade-offs: Exotic Invaders Are a Threat to Our Forests Image Photo by Kenneth R. Law/USDA Aphis

Gary Lovett noted that the forests of the eastern and north-central U.S. are some of the continent’s most vulnerable to imported pests and diseases. They lie near the busiest ports in the U.S., and ports that have been operating for a long time. Also, the forests in those regions are similar in makeup to those in China and Europe. “You bring a pest over here, and it encounters a similar tree species it can feed on, but that species doesn’t have any built-in resistance to the pest, and the pest doesn’t have the enemies that help control its population in its home range,” he said.

Arrayed against this tsunami of shipping containers is a long, thin line of agricultural inspectors from Customs and Border Protection (CBP), an arm of the Department of Homeland Security, and from the U.S. Animal and Plant Health Inspection Service (APHIS), a branch of the Department of Agriculture. CBP inspects cargo at ports, airports, and road crossings; APHIS sets plant protection policies, inspects live plants, and is responsible for quarantines and eradications.

Customs and Border Protection declined our requests to interview inspectors and watch them at work going through containers entering the Port of Boston. They gave no reason. A CBP spokesperson pointed us to information made public on the agency’s website.

According to CBP’s own figures, on a typical day last year, the agency processed over a million passengers; more than a quarter-million privately owned vehicles; and more than 72,000 truck, rail, and sea containers. The agency has nearly 60,000 employees – including almost 23,000 officers and over 20,000 border patrol agents – but only 2,413 “agriculture specialists.” On a typical day, agents seize 470 pests and 4,548 materials for quarantine, including plants, meat, animal by-products, and soil.

Keep in mind that CBP isn’t just tasked with intercepting pallets and crating and inspecting the nooks and crannies of ships and shipping containers. It is also looking out for drugs, illicit currency, and other smuggled items, including humans. They work to nab criminals and terrorists and find illegal aliens and victims of human trafficking.

Some of the things we had wanted to ask CBP higher-ups included how inspectors choose which containers to open and go through, how long they spend with each container, and what percentage of containers are physically inspected.

We had a little more luck with APHIS, where a spokesperson, in email responses to questions, said CBP’s agricultural inspectors are trained jointly by APHIS and CBP. The 10-week course for rookie inspectors includes coursework in plant pathology, pest interception, regulatory decisionmaking, taxonomic entomology, and other disciplines.

Once in the field, these inspectors go through cargo and packing looking for pests, employing tools as commonplace as flashlights to illuminate the dark recesses of a shipping container and crowbars to take apart pallets “to observe wood boring pests within the wood packaging material,” she wrote. They examine a shipment’s documentation to determine if it meets APHIS entrance requirements.

If pests are found, they’re sent to laboratories for identification. The materials in which they were found and the goods they accompanied are “reexported” – in other words, put back into the shipping container, reloaded onto the ship, and sent out to sea.

Exotic bugs have been found in some interesting places. According to CBP’s website, Asian longhorned beetle larvae were found in the stocks of shotguns shipped from Turkey, wood borers were found in wooden packing material holding auto parts from China, and adult wood boring beetles were found in pallets carrying laser-printer toner cartridges from Mexico.

In January, CBP agents at the Port of Philadelphia found a long-horned beetle new to the U.S. in a shipment of pineapples from Costa Rica, and in March, agents at the Port of Baltimore found dead larvae of the Khapra beetle, a major grain pest, in a shipment of cumin seeds from India.

A Regulatory Response

Trying to inspect all of the shipments into the U.S. is a bit like the old tale of the little Dutch boy plugging holes in a dike with his thumbs. Despite all the infested shipments the CBP intercepts and reexports, some make it through with their pests intact and ready to creep, crawl, or fly. In Fading Forests III, Faith Thompson Campbell and Scott Schlarbaum cited an estimate that 13,000 infested containers a year get through the border agency’s net.

Once in the country, no one knows where a shipping container will end up or what will be done with the wooden packaging material. Once nonnative pests are established in an area, a process that doesn’t happen overnight, it is almost impossible to eradicate or contain them.

There has been some progress. One big step was adoption in 2004 by the International Plant Protection Convention of the International Standards for Phytosanitary Measures Number 15. It requires that wood packaging be heat-treated or fumigated for pests. As a result, wooden packaging materials entering the U.S. must be stamped with a special IPCC mark showing that they have been treated.

But since pests are still being found, it’s obvious that the requirement is no panacea, perhaps in part because counterfeit stamps are now common in certain regions of the world, including Africa and Latin America.

Trade-offs: Exotic Invaders Are a Threat to Our Forests Image Photo by James Tourtellotte / CBP

Gary Lovett pointed out that treatment doesn’t guarantee sanitation. One study, he said, estimated that the treatment process was “getting only about 50 percent of the bugs” for three reasons: the treatment doesn’t always work and some insects survive; fraud, where material is stamped but left untreated; and packaging materials and pallets that have been treated may be left outdoors and reinfested.

Simply intercepting pests at the border isn’t enough. Policy changes are needed to reduce the influx of forest pests and diseases.

Recommendations outlined in Fading Forests III and the study by the Cary Institute and its partners include prohibiting the importation of wood packaging, effectively mandating a switch to plastic pallets or ones made out of wood or paper composites; prohibiting the importation of live woody plants or requiring foreign nurseries to adopt measures to ensure that plants exported to the U.S. are free of diseases and pests; fining importers who receive shipments of noncompliant packaging (currently, importers aren’t fined until they’ve amassed five violations in a single year); making pest-prevention programs a priority with key trading partners; setting up partnerships with exporters abroad to ensure that shipments are clean, using U.S. agents abroad to monitor compliance; and expanding pest-surveillance programs around major ports.

One effect that such recommendations would have is to shift the costs of exotic-pest prevention from American taxpayers – who now shoulder most of the bill for border inspections and combating pests once they get here – to importers, who, as Lovett notes, have the most to gain from importation, but who now often find it cheaper to ignore best practices for controlling hitchhiking pests. And the bill for dealing with exotic pests is not inconsiderable: emerald ash borer alone is expected to have cost the country $12.7 billion by 2020, according to the Ecological Applications paper.

“There are a lot of things that could be done that are intellectually simple and – one would think – economically worthwhile, but things are not getting done,” said Campbell. “Government agencies want to say that they’ve got it under control. Yes, we have to find ways to deal with the ones out there already. But meanwhile, we know how to shut the damned door, and let’s do that.”

But if recent history is any guide, changes won’t happen quickly. It sometimes takes federal agencies like APHIS years to effect a policy change.

Part of that undoubtedly stems from APHIS’s dual mandate – to promote international trade, while at the same time protecting the U.S. from the plant and animal pests and diseases associated with that trade.

Asked about how that awkward dual mission balances out on the ground, APHIS responded that the mission of its Plant Protection and Quarantine arm “is to safeguard U.S. agriculture and facilitate the safe trade of agriculture products.” APHIS said it “facilitates trade on low-risk commodities [and] manages risks through import requirements. Strategically, inspections are focused on higher-risk commodities. CBP is committed to helping APHIS fulfill its mission.”

As to the criticism that APHIS sometimes doesn’t move fast enough, an agency spokesperson noted that APHIS “routinely” issues immediately effective federal orders “in response to an emergency when APHIS considers it necessary to take regulatory action to protect agriculture or prevent the entry and establishment into the United States of a pest or disease.” On May 5, for instance, it issued a federal order preventing goods that could host the Mediterranean fruit fly from being imported from Aruba.

APHIS is charged with protecting “the health and value of American agriculture and natural resources,” which is a broad mandate. In addition to interdicting and containing forest and agricultural pests, other programs under its direction involve biotechnology, animal welfare, wildlife-damage management, emergency response, and research, the agency said.

Of course, most Americans have probably never heard of APHIS. This brings us to another problem: the lack of a groundswell of indignation about the rising tide of imported forest pests and diseases – the absence of a coalition of concerned citizens willing to make a holy stink about the whole mess.

Part of that is a result of who we are as Americans these days: increasingly urbanized and disconnected from nature. Too many people can’t tell a maple from an oak, a pine from a spruce. Green is seen as good, even if it’s a subdivision-sized patch of invasive Japanese barberry or a thicket of autumn olive.

Media attention usually fails to put things into context, and the public’s attention span is short anyway. Absent a fast-moving and visible epidemic, like that of the ash borer and the subsequent disappearance of street trees across entire cities, states, and regions, much of the crisis is taking place out of sight and mind, and in slow motion. Harvard biologist E. O. Wilson has written of the concept of “diminishment” – how people fail to notice the changes that lead to a poorer, less diverse, and less resilient environment, because the changes take place in real time and don’t tend to work their way into the public consciousness until, perhaps, people wake up one day and realize that the world they’re living in has changed radically. It’s the old tale of the frog in the pan that gets boiled because it doesn’t feel the gradually rising temperature of the water.

“Government responds slowly and only partially, and then trying to get them to say, ‘oops, that isn’t good enough, we need to do more’ is almost impossible,” said Campbell. “And who is really pounding on them, or offering them a parade to join? Government leaders respond to two things: fear and pressure. We haven’t created either of those two situations.”

Shippers and advocates for global trade have a powerful lobby. Forest advocates are, like many forests themselves, fragmented. Campbell noted that she’s had trouble “even getting advocates of urban forestry to join in on this thing.” Lovett said, “APHIS, in particular, if you get them in a private moment, they admit that they don’t hear from the forest advocacy community; they only hear from the shipping community.”

Lovett is hoping the Cary Institute’s new report on the threat and the Institute’s recommendations for remedies can help rally a coalition of forestry advocates and policymakers to help turn the tide and get some new protections in place.

Without that sort of effort, things don’t look good. “I saw one estimate from a paper that the number of wood-boring beetles, some of the most devastating pests, could easily triple before 2050,” said Lovett. “You could have three times more wood-boring beetle species in the country than we currently have.”

The Future of the Forests

Lovett’s job is studying forests, but he said that it’s “hard to say” what U.S. forests will look like in 50 or 100 years, given the pressures they endure. If one species drops out of the canopy, another will take its place – that’s a given – but when one species replaces another, it leads to ecosystem changes that are hard to predict.

“What you think about when you think about severe damage is dead trees,” he said. “That’s a short-term response to the invasion of a pest. The longer-term response is that we are losing some species and changing the species composition of the forest. If we lose hemlock due to hemlock woolly adelgid, CBPlots of things – birds, insects, soils – will change as well. The same for ash. We notice the death and destruction, but the longer-term impacts are just as substantial.”

Trade-offs: Exotic Invaders Are a Threat to Our Forests Image Photo by James Tourtellotte / CBP

Restoration efforts – attempts to breed pest-resistant tree species – are costly, difficult, and require a huge investment in infrastructure. They’re usually focused on producing faster-growing trees for plantations rather than reintroducing an extirpated species into a complex ecosystem, said Schlarbaum. And they can’t be done from one place. As he noted, breeding adelgid-resistant hemlocks to grow in Tennessee is different from breeding them for Maine, where climate and growing conditions are markedly different. Ironically, the need for increased restoration efforts comes at a time when tree improvement programs are in decline nationally, and funding, as Fading Forests dryly notes, “is woefully deficient.”

One of the most publicized restoration efforts is the decades-long attempt to breed blight-resistant American chestnut trees for reintroduction into eastern forests. Even if successful, it might not be enough to bring back this iconic species. That’s because the threats to the chestnut have multiplied since the blight virtually cleared it from the forests. Today, the chestnut is vulnerable not only to the blight, but to Phytophthora root rot, the chestnut gall wasp, the Asian ambrosia beetle, and the Asiatic oak weevil, which – despite its name – prefers chestnuts to oaks. Breeding for resistance to more than one pest is exponentially harder than breeding for resistance to a single pest or disease.

Then there’s climate change. No one knows how that will factor into the spread of exotic diseases and pests, but if trees are stressed by climate change, that might make them more vulnerable to other threats.

Campbell believes climate change will “speed up the mixmaster.” And while it’s hard to predict which exotics will do better with warming temperatures and which will do worse, the continent may become more hospitable to insects from semi-tropical regions.

So there’s the problem of trying to get the public to care and policymakers to act quickly to stop the importation of new pests and diseases, while at the same time we need to try to prevent the spread of the ones that are already here. It’s hard for this not to seem like pushing a rope uphill.

Given the track record of the past few decades, the outlook is not good. Where policy changes have been made, they’ve made a difference, Campbell and Schlarbaum noted in Fading Forests III. But, the report added, “history shows that needed changes are often slow to be developed and implemented, incomplete in scope, inconsistent, poorly enforced, and underfunded.”

Asked whether she’s optimistic or pessimistic that timely action will be taken, Campbell, who is also on the Carey Institute’s forest pest team, admitted she’s “pessimistic but determined to keep trying to improve” things.

“Trees are wonders of nature that provide us with lots of values. And it’s important for us to protect them. I like them standing up and green, thank you very much,” Campbell said. “I want people in decision-making positions or opinion-forming positions to recognize the importance of protecting our natural resources from this threat. Then they have to believe that there are answers to these problems and have to seize those answers and not just walk away.”

Gary Lovett acknowledged that, “It is hard not to feel depressed about this, but we are not helpless. This is a big problem, but it can be fixed, or at least lessened.”

Trade-offs: Exotic Invaders Are a Threat to Our Forests Image Photo by Anson Eaglin / USDA

There are a handful of actions that average Americans can take that would make a difference, Lovett said: avoid buying imported plants, don’t move firewood, and speak up about the issue by emailing or phoning your congressman or senator or reaching out to environmental groups you belong to. “If enough people do this, then it will get on the radar screen of some legislators, and that is the first step,” he said.

In June, a month and a half after the Cary Institute partners released their report, Lovett was convinced the issue was finally getting some traction where it counted. “We got a lot of media attention (with the release of the report) and I didn’t think we would get that much,” he said. The Washington Post, The Boston Globe, the AP, and other major outlets did stories.

An Institute team went to Washington, D.C., to talk to congresspeople and their aides. Lovett thought that they might get 20 or so people at a briefing, but they filled a 50-person room. Then “we visited a lot of congressional offices and heard a lot of positive things and not any negative things. I’m feeling very good about it. There’s some momentum,” Lovett said.

The team is going to Washington again in July to talk to congressional staffers working to draft legislation to address the problem of keeping forest pests and pathogens out of the country, he said. “We have some of the committee staff, particularly on the Senate Agriculture Committee, who are raring to go,” said Lovett. But he’s also realistic: it’s a challenge keeping anyone’s attention on forest pests in an election year in which both the presidency and some Senate seats are being hotly contested.

“When we talked last time I didn’t know what was going to happen. I’m more optimistic now about the prospects for change than I’ve ever been,” he said.

Joe Rankin is a forestry writer. He lives in Maine.

This article was supported by Northern Woodlands magazine’s Research and Reporting Fund, established by generous donors.


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