September 2022 – Center for Invasive Species Prevention

APHIS: Release Study of Pest Approach Rates!

I have posted nearly 40 blogs about wood packaging (SWPM) since 2015. [You can view these by scrolling below archives to find category “wood packaging”.]

I first raised the need for APHIS to authorize Robert Haack to update his study analyzing pest “approach rates” in wood packaging in July 2018.

Why?

SWPM has delivered our worst forest pests.

SWPM has been recognized as a major pathway of introduction of wood-boring insects for 30 years. Examples include the Asian longhorned beetle, emerald ash borer, redbay ambrosia beetle, and, possibly, the invasive shot hole borers.

For decades, pest-infested wood packaging has come primarily from the same countries: Mexico, Italy, China, and, more recently, Turkey. Many of our most damaging invaders have come from Asia so growing import volumes from Vietnam and other Asian countries also raise concern.

2) The U.S. and Canada have required that wood be treated to kill pests for at least 16 years.

The U.S. and Canada fully implemented the international standard on wood packaging (ISPM#15) in early 2006 – nearly 17 years ago. They had earlier (1999) required treatment of SWPM from China – nearly 24 years ago.

3) Even old analyses concluded that more than 11,000 incoming containers harbored wood pests each year.

The U.S., Canada, and Mexico import more than 31 million shipping containers per year (see “Background” below). Applying decade-old estimates to this number, we conclude that 11,600 of these containers are probably transporting a quarantine wood-boring pest. About 80% of the containers – and probably the pests! – come to U.S. ports. This pest risk is not limited to the West Coast; expansion of the Panama Canal and congestion at West Coast ports mean that an increasing number of ships are travelling directly to ports on the East and Gulf coasts. These region have already been demonstrated to be highly vulnerable to pests from Asia (ranging from Dutch elm disease and Asian longhorned beetle to laurel wilt and beech leaf disease.)

dead redbay trees – killed by redbay ambrosia beetle + laurel wilt fungus – introduced from Asia to Savannah, Georgia

4) Efforts to reduce the pest “approach rate” have not worked yet.

Meantime, administrative efforts to reduce the numbers of containers carrying pests have not been successful. The Bureau of Customs and Border Protection (CBP) has tried. CBP began penalizing individual shipments that are not in compliance with ISPM#15 in 2017 — 5 years ago.

As of the first three-quarters of Fiscal Year 2022 (John Sagle pers. comm. and Crenshaw-Nolan of CBD to Continental Dialogue on Non-Native Forest Insects and Diseases, September 2022), CBP has issued 510 Emergency Action Notifications (EAN) for noncompliant SWPM. About 38% (194) were issued because actionable pests had been discovered. The rest were issued because the ISPM#15 stamp (attesting to the wood having been treated) was either missing or fraudulent. The full-year interception rate will probably be comparable to interceptions in recent years: in FY2021, 548 EANs; in FY2020, 509; in FY2019, 746. CBP staff are disappointed that interceptions have not declined.

5) APHIS has avoided stricter enforcement.

APHIS has not adopted an enforcement stance. It has not stiffened penalties. The agency did not raise these phytosanitary issues when it negotiated a major agriculture trade agreement with China in 2020. The agency continued to insist that ISPM#15 is working – but agreed to work with Robert Haack to re-evaluate the approach rate only in 2021.

Correction: I became alarmed when the study had not been released four months after the analysis was completed (in May). I have since learned that the findings had not yet been completely written up and that internal reviews were proceeding. I apologize for the criticism in the original version of this blog. I impatiently await the study’s release, which I hope will be in a few weeks or months.

In the meantime, APHIS has also hired the Entomological Society to carry out an extensive study that includes analysis of interception data from five ports over a period of five years and rearing insects extracted from incoming wood packaging. I don’t want to postpone action aimed at curtailing introductions via this pathway for another five years!

APHIS has instead tried to improve foreign suppliers’ and phytosanitary agencies’ compliance with ISPM#15 through education. In partnership with Canada and Mexico, APHIS has supported two regional education workshops sponsored by the North American Plant Protection Organization (NAPPO). APHIS is now expanding its outreach to smaller companies, industry associations, and foreign suppliers. APHIS and CBP are now collaborating with an industry initiative to train inspectors that insure other aspects of foreign purchases. In addition, the International Plant Protection Convention (IPPC) is developing a “guidance document”. These educational efforts are supported by the U.S. pallet trade association, National Wooden Pallet and Container Association.

For all of these reasons we urgently need the updated data on the pest approach rate in the analysis by Haack and colleagues. Until we see these results, we can’t know the current level of risk associated with growing volumes of imports or assess the effectiveness of new policies. For example, CBP incorporated compliance with ISPM#15 into its government-importer partnership aimed at ensuring cleanliness of supply chains (C-TPAT) in February 2021. Only by comparing the results of the “approach rate” study with future data collected using the same techniques will it be possible to know how effective this action has been. I greatly appreciate CBP’s efforts.

There is still the issue of untrustworthy stamps.

Past data indicate a high proportion – 87% – 95% — of the SWPM found to be infested bore the ISPM#15 stamp. The same proportion was found in a narrower study in Europe (Eyre et al. 2018). Nor are all problems associated with Asia – importers in Houston have complained that stamps on dunnage from Europe also cannot be trusted.

While there are questions about whether this breakdown results from treatment inadequacy (i.e., 56^oC for 30 minutes does not kill the larvae), failure of application, or of fraud –

What matters is that neither regulators nor importers can rely on the stamp to identify pest-free wood packaging.

infested wood packaging bearing ISPM#15 mark; photo courtesy of Oregon Department of Agriculture

(True: ISPM#15 was never intended to prevent pest introductions, only to “reduce the risk of introduction and spread of quarantine pests associated with the movement in international trade of wood packaging material made from raw wood.” Still, we should be trying to minimize pest introductions which threaten our wildland, rural, and urban forests.)

CPB’s experience indicates that cracking down on individual shipments will not be sufficient.

Immediate actions to hold foreign suppliers responsible

U.S. and Canada refuse to accept wood packaging from foreign suppliers that have a record of repeated violations – whatever the apparent cause of the non-compliance. Institute severe penalties to deter foreign suppliers from taking devious steps to escape being associated with their violation record.
APHIS and CBP and their Canadian counterparts provide guidance to importers on which foreign treatment facilities have a record of poor compliance or suspected fraud – so they can avoid purchasing SWPM from them. I am hopeful that the voluntary industry program described here will help importers avoid using wood packaging from unreliable suppliers in the exporting country.
Encourage rapid switch to materials that won’t transport wood-borers. Plastic is one such material. While no one wants to encourage production of more plastic, the Earth is drowning under discarded plastic. Some firms are recycling plastic waste into pallets.

APHIS and CFIA have the authority to take these actions under the “emergency action” provision (Sec. 5.7) of the World Trade Organization’s Agreement on the Application of Sanitary and Phytosanitary Standards (WTO SPS Agreement). (For a discussion of the SPS Agreement, go to Fading Forests II, here.)

APHIS should also release the findings of the 2021-2022 study of approach rates by Haack and colleagues. Then the agency should invite stakeholders to discuss the implications, then develop and implement protective strategy reflecting its findings.

Longer-term Actions

APHIS and CFIA should cite their need for setting a higher “level of protection” to minimize introductions of pest that threaten our forests (described inter alia here.) They should then prepare a risk assessment to justify adopting more restrictive regulations that would prohibit use of packaging made from solid wood – at least from the countries with records of high levels of non-compliance.

Michigan champion green ash killed by emerald ash borer

APHIS and CFIA should also undertake the studies needed to determine the cause of the continuing issue of the wood treatment mark’s unreliability, then act to resolve it. Preferably, this work should be conducted with other countries and such international entities as the IPPC & International Forest Quarantine Research Group (IFQRG). However, if attempting such collaboration causes delays, they should begin unilaterally. Upcoming opportunities to address this issue include:

FAO International Day of Forests in 2023
FAO global assessment of forests & health – pest & disease outbreaks

Of course, these steps should be based on the findings of Haack and colleagues.

Meanwhile, what can we do?

Urge Congress to conduct oversight on APHIS’ failure to protect America’s natural resources from continuing introductions of nonnative insects and diseases.
- These hearings should be in the context of drafting the 2023 Farm Bill.
Raise the issue with local, state, and federal candidates for office;
Urge Congress to include provisions of H.R. 1389 in the 2023 Farm Bill;
Ask any associations of which we are members to join in communicating these concerns to Congressional representatives and senators. These include:
- if you work for a federal or state agency – raise to leadership; they can act directly or through National Plant Board, National Association of State Departments of Agriculture, National Association of State Foresters, National Governors Association, National Association of Counties
- scientific membership societies – e.g., Society of American Foresters, Entomological Society of America, American Phytopathological Society;
- individual conservation organizations, either with state chapters or at the national level;
- woodland owners’ organizations, e.g., National Woodland Owners Association, National Alliance of Forest Owners (NAFO) and their state chapters
- urban tree advocates
- International Forest Quarantine Research Group
Write letters to the editors of your local newspaper or TV news station.

BACKGROUND: Calculation of the Number of Infested Containers Entering U.S.

As of 2020 (when trade was greatly depressed by the COVID-19 pandemic), nearly 31 million TEUs [a standardized measure for containerized shipment; defined as the equivalent of a 20-foot long container] entered North America. Ports in the U.S. received 80% (24.5 million); Canada 11.5% (3.5 million); Mexico ~9% (2.7 million). U.S. imports have grown substantially since 2020; during the first quarter of 2022 U.S. imports from Asia each month were 20 to 30% higher than in 2019 before COVID-19 disrupted supply chains (blog #292). The U.S. is projected to handle ~26 million TEUs in 2022 [sources here and here.

A “TEU” equals a 20-feet container. Most containers now are twice as large – 40-feet. Several steps are involved in applying findings of Haack et al. 2014 and Meissner 2009 estimates:

divide estimated number of containers (26 million) in half = 13 million.
Assume that three-quarters of that number (13 million) contain wood packaging (based on Meissner) = 9.75 million.
If 1 out of each thousand of these containers with wood packaging is transporting a pest = 9,750 containers / year.

I performed the same calculation for North America-wide estimate of 31 million TEUs discussed at the beginning of the blog.

container being offloaded at Savannah harbor; photo by F.T. Campbell

A separate study (Hudgins et al. 2022) projected that introduction of a new woodboring insect pest that attacks maples or oaks it could kill 6.1 million trees and cost American cities $4.9 billion over 30 years. The risk would be highest if this pest were introduced via a port in the South. I have blogged often about the rising rate of shipments coming directly from Asia to the American South.

An analysis of fungi associated with Eurasian bark and ambrosia beetles reached a conclusion that the authors consider to be more optimistic. Li et al. (2021) found that none of the 111 fungi was sufficiently virulent to trigger tree mortality after a single-point inoculation. This level of lethality was considered analagous to Dutch elm disease DMF or laurel wilt DMF. Thirty-eight percent of the fungi were considered to be weak or localized pathogens that could kill trees under certain conditions. However, they tested the fungi against only two oak and two pine species. They did not evaluate fungi that might be lethal when the vector beetle engages in mass attacks. Finally, I think phytosanitary agencies should act promptly when a pathogen threatens levels of mortality somewhat below Dutch elm disease and laurel wilt!

SOURCES

Hudgins, E.J., F.H. Koch, M.J. Ambrose, B. Leung. 2022. Hotspots of pest-induced US urban tree death, 2020–2050. Journal of Applied Ecology 59(5): 1302-1312.

Li, Y., C. Bateman, J. Skelton, B. Wang, A. Black, Y-T. Huang, A. Gonzalez, M.A. Jusino, Z.J. Nolen, S. Freeman, Z. Mendel, C-Y. Chen, H-F. Li, M. Kolařík, M. Knížek, J-H. Park, W. Sittichaya, P.H. Thai, S-I. Ito, M. Torii, L. Gao, A.J. Johnson, M. Lu, J. Sun, Z. Zhang, D.C. Adams, J. Hulcr. 2021. Pre-invasion assessment of exotic bark beetle-vectored fungi to detect tree-killing pathogens Phytopathology. 112(2): 261–270. https://doi.org/10.1094/PHYTO-01-21-0041-R

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

www.fadingforests.org

Invasive shot hole borers: global threat; will international phytosanitary system prevent further spread?

ISHB-infested California sycamore; photo by Beatriz Nobua-Behrmann, University of California Cooperative Extension

Numerous ambrosia beetles have become introduced species. Their invasions are facilitated by their cryptic habits and ecologies, wide host ranges, and specialized breeding systems – all of which allow extremely low populations to start an infestation. The way they breed often results in low genetic diversity in their introduced ranges, but this has not hampered their success. [Bierman et al. 2022]

Also, ambrosia beetles carry fungi, which provide food needed by their larvae. While most of these fungi don’t harm living trees, some do. The United States has been invaded by three damaging ambrosia beetle-fungal complexes: laurel wilt in the Southeast, and Fusarium dieback disease, carried to southern California with polyphagous and Kuroshio shot hole borers.

These shot hole borers and their fungi represent an especially high risk to our forests because they can be transported in both living and dead wood. So not only massive U.S. imports of live plants but also the global movement of goods enclosed in solid wood packaging offer ready pathways for them to arrive and spread here. Neither pathway is regulated effectively enough to prevent either pest imports or interstate spread.

Invasive ambrosia beetles in California and Hawai’i

The invasive ambrosia beetles introduced to California are in the genus Euwallacea. This genus has undergone several taxonomic revisions. Now, the Euwallacea are divided into four species (Stouthammer 2017), of which three are in the U.S.:

Euwallacea fornicatus s.s. – common name polyphagous shot hole borer; first came to attention in southern California in 2012; formerly known as E. whitfordiodendrus.
E. perbrevis – common name tea shot hole borer; formerly known as E. fornicatus s.l.
E. kuroshio – unchanged nomenclature since detected in California in 2013;
E. fornicatior — apparently has not invaded outside of its native range in Asia.

Those now in the U.S. have been introduced to naïve habitats here and elsewhere, often with dire consequences. E. perbrevis, and possibly other species in the complex, are established on the Hawaiian islands.

For an extensive discussion of their introduction history go here

The Fungi: U.S. and Worldwide

Several fungal associates are vectored by the polyphagous shot hole borer (PSHB) and Kuroshio shot hole borer (KSHB). The most important are Fusarium euwallacea and Fusarium kuroshium, respectively. These fungi were only described after they appeared in California in the 2010s. They cause Fusarium dieback disease.

Because the two beetle species are difficult to distinguish and the associated diseases cause very similar impacts, Californians studying them and educating stakeholders now speak of the two beetle-fungus complexes as one unit, “invasive shot hole borers”.

Both PSHB and KSHB have numerous genetic strains, or haplotypes. For PSHB, the greatest haplotype diversity is in Asia – Thailand, Vietnam and China. Remember that these same regions are also a center of diversity for the huge genus Phytophthora, blog a genus widely recognized as containing many plant pathogens. https://www.dontmovefirewood.org/pest_pathogen/sudden-oak-death-syndrome-html/ One of the PSHB haplotypes, H33, has invaded many more regions than the others, including Israel, California, and South Africa. It has also been detected in several tropical plant greenhouses in Europe (where it has been eradicated). H33apparently is native to Vietnam – near Hanoi and Ho Chi Minh City – the country’s major ports (Rugman-Jones et al 2020 and pers. comm.). Does this haplotype’s spread to three continents reflect circumstances, such as the proximity of its native range to major ports and a “bridgehead effect” from its multiple introductions (the insects can be introduced to new regions on shipments from invaded regions established earlier)? Or does it point to an unknown genetic superiority (Bierman et al. 2022). This issue seems worth exploring.

I have blogged about the rising volume of imports from Vietnam, including to ports on the Gulf Coast –a region that has climatic similarities to Vietnam and known host species, so it seems quite vulnerable to invasion by either PSHB or KSHB.

A second species in the genus, KSHB, was detected in southern California in 2012; it has now spread to Mexico. So far, only one haplotype of this species has been detected in North America; this haplotype is widespread in Taiwan.

Finally, E. perbrevis (formerly known as E. fornicatus s.l.) has been detected in Florida, Hawai`i (island of Maui), and West Australia (to which it is probably native). This species has also been detected in nurseries in the Netherlands, where authorities report that it has been eradicated (Rugman-Jones et al. 2020).

Akacia koa – native tree in Hawai“i attacked by Euwallaceae; photo by David Eckhoff, via Flickr

Some species or haplotypes have been detected in only one introduced location: E. fornicatus H35 and E. kuroshio (H20) in California; H38 in South Africa; H43 on Oahu and the Big Island of Hawai`i; and an unnamed haplotype in West Australia (Rugman-Jones et al. 2020).

This is a brief guide to worldwide invasions by one or more Euwallacea-fungus complexes (Rugman-Jones et al. 2020):

Southern California — two haplotypes of E. fornicatus s.s. (H33 & H35) and E. kuroshio (one haplotype).
Hawai`i – a unique haplotype of E. fornicatus s.s. (H43) on Oahu, the Big Island, and possibly other islands; E. perbrevis on Maui and possibly other islands.
Israel — E. fornicatus s.s. haplotype H33 only.
South Africa — E. fornicatus s.s. haplotype H33 and a unique haplotype (H38).
Western Australia — a unique haplotype of E. fornicatus s.s. and E. perbrevis (which is probably native in northern Queensland).
Greenhouses in Europe – both E. fornicatus s.s. (haplotype not specified) and – in the Netherlands — E. perbrevis; both reported eradicated.

When a location has been invaded by two or more species or haplotypes, this is probably an indication of separate introductions. Multiple introductions thus are suspected in California (Stouthamer et al. 2017; Bierman et al. 2022); South Africa (Bierman et al. 2022); and Hawai`i (Bierman et al. 2022).

As is true of other pathogens, e.g., Phytophthoras, there appears to have been a spurt of introductions in recent decades, to, e.g., California, South Africa, and the second species in Hawai`i. Bierman et al 2022 note the constantly growing number of locations with introductions.

*Indigofera jucuna* – reproductive host of PSHB in South Africa; photo by Giardano de Barcelona

Impact and Spread

As is common in the case of forest pests, especially pathogens, detection occurred only years after the initial introduction. In South Africa this delay was five years – from 2012 to 2017 or 2018. In California, identification of the species as PSHB in 2012 was nine years after the organism was first detected in the state (2003).

Over the decade since 2012, PHSB, KSHB, and the pathogens they transmit have spread through large portions of southern California. KSHB has spread through “jumps” to distant locations in Orange, Los Angeles, and as far as Santa Barbara and Ventura counties. There have also been detections in even more distant San Luis Obispo and Santa Clara. These latter apparently have not become established.

A likely explanation for this pattern is the movement of firewood. (Rugman-Jones et al 2020 and pers. comm.) See the map here The two beetles and the plant pathogens they carry are expected to spread throughout much of California wherever their many host plants occur.

On Hawai`i, PSHB is attacking several endemic species including one of the largest forest trees, Acacia koa, as well as Pipturus albidus and Planchonella sandwicensis. Numerous non-native species growing on the Islandsare also attacked, including crops (Macadamia and Mangifera) and invasive species

In South Africa, PSHB has spread faster and farther. It has been present since at least 2012 (Stouthamer et al. 2017), although it was not identified until 2018. In about a decade it has spread to every province except Limpopo – PSHB’s largest geographical outbreak of this beetle [Bierman et al. 2022]

Hosts and Areas at Greatest Risk

Hundreds of plant species in at least 33 plant families support successful reproduction of both beetle and fungus. These include many species widespread in southern California, other parts of the U.S., and South Africa. Some California ecosystems are at particular risk because they are dominated by susceptible tree or shrub species. These vulnerable ecosystems are mixed evergreen forests, oak woodlands, foothill woodlands, and riparian habitats. In San Diego County alone, more than 58,000 acres of riparian woodlands are at risk (California Forest Pest Council).

Experience with the Kuroshio shot hole borer (KSHB) in the Tijuana River valley along the California-Mexico border demonstrates the importance of ecological factors in determining disease outcomes. Following introduction, the KSHB killed a high proportion of the willows near the main river channel. However, beginning in 2016, these trees have regrown to almost pre-infestation sizes. Lead researcher John Boland is not certain why these new, fast-growing trees have not been attacked by the KSHB which remains in the area. See links to the Boland studies below.

riparian forest in Tijuana River Valley after recovery from KSHB attack; photo by John Bolton

Urban forests are at particular risk. For example, in South Africa, conservative estimates were that 25% of urban trees would be lost (Bierman et al. 2022). In California, a model developed by Shannon Lynch found the cities at greatest jeopardy are San Diego, Los Angeles, the San Francisco Bay area, and Sacramento. In other areas in the state that lack data on city tree composition, Lynch applied climate models; this approach extended the list of threatened areas to the eastern half of southern California and other parts of the Central Valley. (Lynch presentation to ISHB webinar April 2022; 2^nd day.) In my view, this model should also be applied to cities in Arizona and Nevada with similar climates.

Management

Symptoms of PSHB attack and fungus infection differ among tree species. For illustrations of the symptoms on various species, visit here.

Most important, prevent the beetles’ spread through movement of dead or cut wood, e.g., green waste, firewood, and even large wood chips or mulch. Websites provide information on managing these sources.

Where the beetles have already established, California scientists recommend focusing management on heavily infested “amplifier trees”. On these trees, dead limbs should be pruned; dying trees and those with beetles infesting the main trunk should be removed. The wood must be disposed of properly.

Sources

Bierman, A., F. Roets, J.S. Terblanche. 2022. Population structure of the invasive ambrosia beetle, Euwallacea fornicatus, indicates multiple introductions into South Africa. Biol Invasions (2022) 24:2301–2312 https://doi.org/10.1007/s10530-022-02801-x

Boland, J.M. — all of Boland’s reports and articles on the KSHB are available at: The Ecology and Management of the Kuroshio Shot Hole Borer in the Tijuana River Valley — Tijuana Estuary : TRNERR]

California Forest Pest Council. 2015. 2015 California Forest Pest Conditions. http://bofdata.fire.ca.gov/hot_topics_resources/2015_california_forest_pest_conditions_report.pdf

Eskalen, A., Stouthamer, R., Lynch, S. C., Twizeyimana, M., Gonzalez, A., and Thibault, T. 2013. Host range of Fusarium dieback and its ambrosia beetle (Coleoptera: Scolytinae) vector in southern California. Plant Dis. 97:938-951.

Stouthamer, R., P. Rugman-Jones, P.Q. Thu, et al. 2017. Tracing the origin of a cryptic invader: phylogeography of the Euwallacea fornicatus (Coleoptera: Curculionidae: Scolytinae) species complex. Agric For Entomol 19:366-375. https://doi.org/10.1111/afe.12215

recordings of April 2022 webinar posted at https://youtu.be/RyqJYyLkshk day 1; and https://youtu.be/kWmtcbjTczw day 2

Posted by Faith Campbell

www.fadingforests.org

Hundreds of U.S. Tree Species Endangered, Most due to Non-Native Pests

Horton House on Jekyll Island, Georgia before laurel wilt killed the giant redbay trees; photo by F.T. Campbell

Close to four hundred tree species native to the United States are at risk of extinction. The threats come mainly from non-native insects and diseases – a threat we know gets far too little funding, policy attention, and research.

As Murphy Westwood, Vice President of Science and Conservation at the Morton Arboretum, which led the U.S. portion of a major new study, said to Gabriel Popkin, writing for Science: “We have the technology and resources to shift the needle,” she says. “We can make a difference. We have to try.”

Staggering Numbers

More than 100 tree species native to the “lower 48” states are endangered (Carrero et al. 2022; full citation at the end of this blog). These data come from a global effort to evaluate tree species’ conservation status around the world. I reported on the global project and its U.S. component in September 2021. This month Christina Carrero and colleagues (full citation at the end of this blog) published a summary of the overall picture for the 881 “tree” species (including palms and some cacti and yuccas) native to the contiguous U.S. (the “lower 48”).

This study did not address tree species in Hawai`i or the U.S. Pacific and Caribbean territories. However, we know that another 241 Hawaiian tree species are imperiled (Megan Barstow, cited here).

Assessing Threats: IUCN, NatureServe, and CAPTURE

Carrero and colleagues assessed trees’ status by applying methods developed by IUCN and NatureServe. (See the article for descriptions of these methods.) These two systems consider all types of threats. Meanwhile, three years ago Forest Service scientists assessed the specific impacts of non-native insects and pathogens on tree species in the “lower 48” states and Alaska in “Project CAPTURE” (Conservation Assessment and Prioritization of Forest Trees Under Risk of Extirpation). All three systems propose priorities for conservation efforts. For CAPTURE’s, go here.

Analyses carried out under all three systems (IUCN, NatureServe, and CAPTURE) concur that large numbers of tree species are imperiled. Both IUCN and CAPTURE agree that non-native insects and pathogens are a major cause of that endangerment. While the overall number of threatened species remained about the same for all three systems, NatureServe rated threats much lower for many of the tree species that IUCN and CAPTURE considered most imperiled.

This difference arises from the criteria used to rate a species as at risk. IUCN’s Criterion A is reduction in population size. Under this criterion, even extremely widespread and abundant species can qualify as threatened if the population declines by at least 30% over three generations in the past, present, and/or projected future. NatureServe’s assessment takes into account rapid population decline, but also considers other factors, for example, range size, number of occurrences, and total population size. As a result, widespread taxa are less likely to be placed in “at risk” categories in NatureServe’s system.

In my view, the IUCN criteria better reflect our experience with expanding threats from introduced pests. Chestnut blight, white pine blister rust, dogwood anthracnose, emerald ash borer, laurel wilt disease, beech leaf disease, and other examples all show how rapidly introduced pathogens and insects can spread throughout their hosts’ ranges. (All these pests are profiled here . ) They can change a species’ conservation status within decades whether that host is widespread or not.

Which Species Are at Risk: IUCN

Carrero and colleagues found that under both IUCN and NatureServe criteria, 11% to 16% of the 881 species native to the “lower 48” states are endangered. Another five species are possibly extinct in the wild. Four of the extinct species are hawthorns (Crataegus); the fifth is the Franklin tree (Franklinia alatamaha) from Georgia. A single specimen of a sixth species, an oak native to Texas (Quercus tardifolia),was recently re-discovered in Big Bend National Park.

Franklinia (with Bachman’s warbler); both are extinct in the wild; painting by John Jacob Audubon

The oak and hawthorn genera each has more than 80 species. Relying on the IUCN process, Carrero and colleagues found that a significant number of these are at risk: 17 oaks (20% of all species in the genus); 29 hawthorns (34.5% percent). A similar proportion of species in the fir (Abies), birch (Betula), and walnut (Juglans) genera are also threatened.

Other genera have an even higher proportion of their species under threat, per the IUCN process:

all species in five tree genera, including Persea (redbay, swampbay) and Torreya (yews);
two-thirds of chestnuts and chinkapins (Castanea), and cypress (Cupressus);
almost half (46.7%) of ash trees (Fraxinus).

Pines are less threatened as a group, with 15% of species under threat. However, some of these pines are keystone species in their ecosystems, for example the whitebark pine of high western mountains.

Carrero et al. conclude that the principal threats to these tree species are problematic and invasive species; climate change and severe weather; modifications of natural systems; and overharvest (especially logging). Non-native insects and pathogens threaten about 40 species already ranked by the IUCN criteria as being at risk and another 100 species that are not so ranked. Climate change is threatening about 90 species overall.

Considering the invasive species threat, Carrero and colleagues cite specifically ash trees and the bays (Persea spp.). In only 30 years, the emerald ash borer has put five of 14 ash species at risk. All these species are widespread, so they are unlikely to be threatened by other, more localized, causes. In about 20 years, laurel wilt disease threatens to cause extinction of all U.S. tree species in the Persea genus.

Carrero and colleagues note that conservation and restoration of a country’s trees and native forests are extremely important in achieving other conservation goals, including mitigating climate change, regulating water cycles, removing pollutants from the air, and supporting human well-being. They note also forests’ economic importance.

As I noted above, USFS scientists’ “Project CAPTURE” also identified species that deserve immediate conservation efforts.

Where Risk Assessments Diverge

All three systems for assessing risks agree about the severe threat to narrowly endemic Florida torreya and Carolina hemlock.

With three risk ranking systems, all can agree (as above), all can disagree, or pairs can agree in four different ways. Groups of trees fall into each pair, with various degrees of divergence. Generally, only two of the three systems agree on more widespread species:

black ash: IUCN and Project CAPTURE prioritize this species. NatureServe ranked it as “secure” (G5) as recently as 2016.
whitebark pine: considered endangered by IUCN, “vulnerable” (G3) by NatureServe. The US Fish and Wildlife Service has proposed listing the species as “threatened” under the Endangered Species Act. https://www.fws.gov/species-publication-action/endangered-and-threatened-wildlife-and-plants-threatened-species-18 However, Project CAPTURE does not include it among its highest priorities for conservation. Perhaps this is because there are significant resistance breeding and restoration projects already under way.
tanoak: considered secure by both IUCN and NatureServe, but prioritized by Project CAPTURE for protection.

dead tanoak in Curry County, Oregon; photo by Oregon Department of Forestry

Carrero notes the divergence between IUCN and NatureServe regarding ashes. Four species ranked “apparently secure” (G4) by NatureServe (Carolina, pumpkin, white, and green ash) are all considered vulnerable by IUCN. They are also prioritized by Project CAPTURE. I have described the impact of the emerald ash borer on black ash. Deborah McCullough, noted expert on ash status after invasion by the emerald ash borer, also objects to designating this species as “secure” (pers. comm.).

This same divergence appears for eastern hemlock.

Port-Orford cedar is currently ranked as at risk by IUCN and Project CAPTURE, but not NatureServe. Growing success of the restoration breeding project has prompted IUCN to change the species’ rank from “vulnerable” to “near threatened”. IUCN is expected to reclassify it as of “least concern” in about a decade if breeding efforts continue to be successful (Sniezko presentation to POC restoration webinar February 2022).

While these differing detailed assessments are puzzling, the main points are clear: several hundred of America’s tree species (including many in Hawai`i, which – after all – is our 50^th state!) are endangered and current conservation and restoration efforts are inadequate.

Furthermore, a tree species loses its function in the ecosystem long before it becomes extinct. It might still be quite numerous throughout its range – but if each individual has shrunken in size it cannot provide the same ecosystem services. Think of thickets of beech root sprouts – they cannot provide the bounteous nut crops and nesting cavities so important to wildlife. Extinction is the extreme. We should act to conserve species much earlier.

YOU CAN HELP!

Congress is considering the next Farm Bill – which is due to be adopted in 2023. Despite its title, this legislation has often provided authorization and funding for forest conservation (for example, the US Forest Service’ Landscape Scale Restoration Program).

There is already a bill in the House of Representatives aimed at improving the US Department of Agriculture’s prevention and early detection/rapid response programs for invasive pests. Also, it would greatly enhance efforts to restore decimated tree species via resistance breeding, biocontrol, and other strategies. This bill is H.R. 1389.

The bill was introduced by Rep. Peter Welch of Vermont, who has been a solid ally and led on this issue for several years. As of August 2022, the bill has seven cosponsors, most from the Northeast: Rep. Mike Thompson [CA], Rep. Chellie Pingree [ME], Reps. Ann M. Kuster and Chris Pappas [NH], Rep. Elise Stefanik [NY], Rep. Deborah K. Ross [NC], Rep. Brian Fitzpatrick [PA].

Please write your Representative and Senators. Urge them to seek incorporation of H.R. 1389 in the 2023 Farm Bill. Also, ask them to become co-sponsors for the House or Senate bills. (Members of the key House and Senate Committees are listed below, along with supporting organizations and other details.)

Details of the Proposed Legislation

The Invasive Species Prevention and Forest Restoration Act [H.R. 1389]

Expands USDA APHIS’ access to emergency funding to combat invasive species when existing federal funds are insufficient and broadens the range of actives that these funds can support.
Establishes a grant program to support research on resistance breeding, biocontrol, and other methods to counter tree-killing introduced insects and pathogens.
Establishes a second grant program to support application of promising research findings from the first grant program, that is, entities that will grow large numbers of pest-resistant propagules, plant them in forests – and care for them so they survive and thrive.
[A successful restoration program requires both early-stage research to identify strategies and other scientists and institutions who can apply that learning; see how the fit together here.]

Mandates a study to identify actions needed to overcome the lack of centralization and prioritization of non-native insect and pathogen research and response within the federal government, and develop national strategies for saving tree species.

Incorporating the provisions of H.R. 1389 into the 2023 Farm Bill would boost USDA’s efforts to counter bioinvasion. As Carrera and colleagues and the Morton Arboretum study on which their paper is based demonstrate, our tree species desperately need stronger policies and more generous funding. Federal and state measures to prevent more non-native pathogen and insect pest introductions – and the funding to support this work – have been insufficient for years. New tree-killing pests continue to enter the country and make that deficit larger –see beech leaf disease here. Those here, spread – see emerald ash borer to Oregon.

For example, funding for the USDA Forest Service Forest Health Protection program has been cut by about 50%; funding for USFS Research projects that target 10 high-profile non-native pests has been cut by about 70%.

H.R. 1389 is endorsed by several organizations in the Northeast: Audubon Vermont, the Maine Woodland Owners Association, Massachusetts Forest Alliance, The Nature Conservancy Vermont, the New Hampshire Timberland Owners Association, Vermont Woodlands Association, and the Pennsylvania Forestry Association.

Also, major forest-related national organizations support the bill: The American Chestnut Foundation (TACF), American Forest Foundation, The Association of Consulting Foresters (ACF), Center for Invasive Species Prevention, Ecological Society of America, Entomological Society of America, National Alliance of Forest Owners (NAFO), National Association of State Foresters (NASF), National Woodland Owners Association (NWOA), North American Invasive Species Management Association (NAISMA), Reduce Risk from Invasive Species Coalition, The Society of American Foresters (SAF).

HOUSE AND SENATE AGRICULTURE COMMITTEE MEMBERS – BY STATE

STATE	Member, House Committee	Member, Senate Committee	Key members * committee leadership # forestry subcommittee leadership @ cosponsor of H.R. 1389
Alabama	Barry Moore
Arizona	Tom O’Halleran
Arkansas	Rick Crawford	John Boozman*
California	Jim Costa Salud Carbajal Ro Khanna Lou Correa Josh Harder Jimmie Panetta Doug LaMalfa
Colorado		Michael Bennet #
Connecticut	Jahana Hayes
Florida	Al Lawson Kat Cammack
Georgia	David Scott * Sanford Bishop Austin Scott Rick Allen	Raphael Warnock Tommy Tuberville
Illinois	Bobby Rush Cheri Bustos Rodney Davis Mary Miller	Richard Durbin	Note that the report was led by scientists at the Morton Arboretum – in Illinois!
Indiana	Jim Baird	Mike Braun
Iowa	Cindy Axne Randy Feenstra	Joni Ernst Charles Grassley
Kansas	Sharice Davids Tracey Mann	Roger Marshall#
Kentucky		Mitch McConnell
Maine	Chellie Pingree @
Massachusetts	Jim McGovern
Michigan		Debbie Stabenow *
Minnesota	Angie Craig Michelle Fischbach	Amy Klobuchar Tina Smith
Mississippi	Trent Kelly	Cindy Hyde-Smith
Missouri	Vicky Hartzler
Nebraska	Don Bacon	Deb Fischer
New Hampshire	Ann McLane Kuster @
New Jersey		Cory Booker
New Mexico		Ben Ray Lujan
New York	Sean Patrick Maloney Chris Jacobs	Kristen Gillibrand
North Carolina	Alma Adams David Rouzer
North Dakota		John Hoeven
Ohio	Shontel Brown Marcy Kaptur Troy Balderson	Sherrod Brown
Pennsylvania	Glenn Thompson
South Dakota	Dusty Johnson	John Thune
Tennessee	Scott DesJarlais
Texas	Michael Cloud Mayra Flores
Vermont		Patrick Leahy
Virginia	Abigail Spanberger #
Washington	Kim Schreir

SOURCES

Christina Carrero, et al. Data sharing for conservation: A standardized checklist of US native tree species and threat assessments to prioritize and coordinate action. Plants People Planet. 2022;1–17. wileyonlinelibrary.com/journal/ppp3

Washington Post: Sarah Kaplan, “As many as one in six U.S. tree species is threatened with extinction” https://www.washingtonpost.com/climate-environment/2022/08/23/extinct-tree-species-sequoias/

Popkin, G. “Up to 135 tree species face extinction—and just eight enjoy federal protection”, Science August 25, 2022. https://www.science.org/content/article/135-u-s-tree-species-face-extinction-and-just-eight-enjoy-federal-protection

Posted by Faith Campbell

www.fadingforests.org

Posted by Faith Campbell