funding – Page 2 – Center for Invasive Species Prevention

American elms: progress on breeding resistance

America elms on a street in Southeast District of Columbia; photo by F.T. Campbell

I applaud recent developments regarding one of the most devastating and widespread non-native tree-killing diseases, “Dutch” elm disease (DED). Brief descriptions of ecological importance of elms, the disease’s impact in North American and Europe, and difficulties in managing the rapidly evolving causal pathogens here. (See also a review of the ecological value of American elm here.)

Restoring America elm would be wonderful, so I rejoice at steps forward.

One task is to improve detection of the disease in forests. Currently detection is tardy because it relies on observation of visual symptoms followed by molecular confirmation. This process demands considerable time and labor; it is also error-prone. Earlier molecular detection methods also are labor intensive, costly, & have operational limitations.

A group of scientists led by Jian Jin and Songlin Fei are testing whether new spectral imaging & artificial intelligence can improve early detection. (See the publication by Wei et al.; full citation at the end of this blog.) Their goal is to detect subtle changes associated w/ disease developments before visual symptoms appear. The new technology — high-precision leaf spectral imagers — is already in use for agr crops. The devices needed are inexpensive and hand-held/portable. Can collect hyper- or multi-spectral images of a whole leaf in the field. This systems is also non-destructive & rapid.

To test applicability of this technology, the scientists inoculated the fungus responsible for DED into trees with known – and varying — disease susceptibilities. Then they collected spectral images of leaves from those trees to test accuracy of analyses conducted via both traditional machine learning & state-of-art deep learning models. These collections were made at three different times: 96 hours after inoculation / before visual symptoms; 4 weeks after inoculation / during visual symptom development; 15 weeks / foliar symptoms noticeable. They recorded the declining status of the using the traditional visual symptoms – wilting, yellowing, browning of leaves.

While detection accuracy varied by time of specimen collection and genetic heritage of the particular tree, machine-learning-based spectral & spatial analysis of high-resolution hyper & multi-spectral leaf images did detect DED symptoms. This advance would help detect pockets of disease in the forest and might be useful in screening elm genotypes for susceptibility to the pathogen. This latter ability would support resistance breeding programs.

However, further study is needed to determine whether light conditions, seasonal variations, or interactions with other pathogens might influence leaves’ spectral signature. Furthermore, scientists should test application of the process to additional elm genotypes. As Enrico Bonello and others have pointed out, however, the ideal would be to detect infection before even the start of symptoms – in other words, to detect even more subtle changes.

A second task is to breed American elms that can survive – even thrive – despite the continuing presence of the disease-causing pathogens. I rejoice here, too. So far, scientists have found varying levels of resistance in large “lingering” elms. This resistance appears to be heritable. Scientists are preparing reports of this progress for publication.

The USFS Northern Research Station is leading efforts of multiple partners to find and screen resistance of large elms across several regions. In New England, the principal partner is The Nature Conservancy; in the upper Midwest partners include the Army Corps of Engineers and Wisconsin Department of Natural Resources, In the lower Midwest the USFS is working with Metroparks Toledo, University of Illinois, Urbana Champaign, Appalachia Ohio Alliance and others. The Great Lakes Basin Forest Health Collaborative is helping to coordinate these efforts.

American elm has a huge range – covering much of the United States east of the Great Plains. Map Restoring the species to that range requires efforts throughout that range – so as to capture the genetic variability within the species and perpetuate its adaptations to the wide range of ecological conditions.

While restoring this magnificent and ecologically important tree species is worthwhile per se, a second motivation has emerged: using elms to restore riparian and wetland ecosystems now being harmed by loss of ash trees to the emerald ash borer.

Knight et al. (full citation at the end of this blog) note that these efforts’ success will depend not only on developing elms that can survive DED. It is also necessary to determine restoration strategies and silvicultural treatments that will promote the young trees’ ability to flourish despite challenges by storms, floods, competition with other plants, and wildlife feeding.

This team of USFS researchers describe ongoing tests of reintroduction strategies & silvicultural requirements in the Service’ Region 9. They note that reintroduction focuses on a single species. The goal of ecosystem restoration requires considering a broader range of factors. Both are important components for the success.

Testing Elm Reintroduction Factors

Research projects they describe include testing results of planting both bare-root seedlings and containerized stock. The latter approach is more labor-intensive but appears to provide better survival. When competing vegetation was removed & then controlled to prevent regrowth, large containerized trees had excellent survival & rapid growth. They also documented the value of caging trees to prevent deer browsing.

Other research projects explore elm seedlings’ ability to tolerate cold, floods, and shade. Scientists in New England and Wisconsin are observing how well progeny from various crosses between DED-tolerant American elms & local survivor trees are enduring the regions’ winters. One test is deploying progeny from paternal lines that are from different plant cold hardiness zones. It will be important to identify and plant trees that are adapted to local environmental conditions on top of being resistant to the DED pathogen.

Another group of tests investigates flood tolerance. Even minor dips or rises on floodplains lead to very different flooding intensities. Some of these experiments also consider shade tolerance. This is because managers hope can establish understory trees poised to grow rapidly by planting elm seedlings before harvest or mortality of canopy trees (e.g., ash). In one experiment in floodplain forests in Ohio, so far many elm seedlings have survived extensive spring & fall flooding. The seedlings are thriving across a range of microsite light environments. Even competition from invasive herbaceous plants does not appear to have impeded the elms’ survival.

DED has two methods of infecting nearby elms: that pathogen is either vectored by beetles that burrow below the tree’s bark, or through direct fungal contact via grafting of roots. Scientist do not yet know whether trees that tolerate DED infections caused by beetle attacks can withstand infection via root grafts. An experiment using paired elms was initiated in 2011. At the time of their writing, the trees had not yet grown sufficiently large to form root grafts – necessary before scientist could begin the experimental inoculations.

Finally, these many plantings have revealed some “unknown unknowns” — factors not previously identified. Knight et al. describe two studies:

1) Under the National Elm Trials, scientists are studying growth, stress and pest resistance, and horticultural performance of DED-tolerant American elm cultivars & other elm species and hybrids in 16 states. (See details here.)

2) A system of sentinel restoration sites has been established. Multiple DED-tolerant American elm selections have been planted in eight locations in four states to be an “early warning” system to identify additional pathogens of concern. Knight cites detection of a wood wasp at one site in Ohio and competition of thick grass and feeding by rodent on their roots in Minnesota.

Testing Restoration Strategies

As Knight et al. remind us, Eastern forests experience many forms of disturbance, including non-native pests and plants, increases in deer populations, land clearing, grazing, & climate change. Foresters want to know whether DED-resistant American elms might be used in restoration plantings in response to these natural and anthropogenic disturbance? They value elm for its ability to thrive in a wide variety of conditions. Furthermore, the species supports a diverse array of insect herbivores, which then support higher trophic levels, e.g., birds (Tallamy 2009). Another factor, not mentioned by Knight et al., is that even vulnerable elms can grow to some size before they are killed by DED. Knight et al. say multiple studies are testing use of American elm as one of several native species to be plant in ash ecosystems devastated by EAB. In northern Minnesota, the experiment is occurring in wet forest ecosystems formerly dominated by black ash. In Ohio researchers are observing elms planted in riparian systems where green ash forests used to be found. They report that early data indicate good initial survival of American elm in both studies.

The Nature Conservancy’s Connecticut River Program planted over 1900 disease-tolerant American elm cultivars at 76 sites in four New England states over the decade 2010 – 2021. Several DED-tolerant selections and their progeny were planted. Survival has varied considerably, they think depending on site factors, e.g., ice flows, height and density of competing vegetation, climate, damage from voles, deer browsing, others.

More recently, the partners have moved away from crossing survivor elms with cultivars because that results in too many related progeny, insufficient genetic diversity. In addition, the trees would not be adapted to the planting site because one parent was not local).

The Nature Conservancy’s participation has been funded by a grant of ~$2.4 million from a private foundation. TNC is helping to identify “lingering” or “survivor” American elm and restore them to floodplains and urban forests across New England. TNC has also funded groundbreaking research at the USFS to accelerate the breeding program and develop best practices for American elm reintroduction.

The Vermont chapter has been particularly active. Since 2014 it has been managing experimental elm trees plantings at 10 TNC natural areas and 26 partner-owned sites across the state. This effort has yielded ~7,000 trees that represent 142 novel crosses between 23 survivor elms identified by TNC in New England & several varieties identified by USFS from other parts of the country. Scientists plan to inoculate these trees in spring 2026. The trees’ vulnerability to the pathogen will then be evaluated over two years.

Knight et al. expect that in a decade or less these and other research projects will contribute needed understanding of various American elm propagules’ cold tolerance, flood tolerance, shade tolerance, response to competing vegetation, & root grafting. This information will allow managers to maximize survival of planted elm trees. It will also demonstrate how to usefully employ elms in ecosystem restoration. They caution that guidelines will probably vary to fit specific situations & site characteristics e.g., forest type, competing species, local hydrology, etc.

Knight et al. also identify topics that require additional research. The first factor mentioned are social & ecological contexts of restoration strategies. Social context will guide the formulation of a more strategic approach — setting goals, addressing such questions as the public perception & value of American elm in urban & forest areas, forest manager goals for incorporation of American elm, & municipal requirements for urban trees. It is essential to determine the long-term durability of resistance. Also need to explore how best to promote spread of DED-tolerant genes given the high numbers of local, non-resistant elms across the landscape. scale strategies.

Knight et al. note that need experimental plantings in additional parts of the species’ enormous range to identify potential problems, test performance on different soil types and in different climates. Need experiments to identify interactions among elm genetics and abiotic & biotic environ variables to guide silvicultural, site preparation, and planting strategies. I have observed apparently thriving American elms along roadways in the Washington, D.C. metropolitan area.

thriving American elm at the Fairfax County landfill in Lorton; photo by F.T. Campbell

I believe no one is protecting them. Certainly other elms in the area have died. So far I have not found people trying to find “lingering” or “survival” elms here. I seek people who want to work with these trees!

dead American elm on National Mall in Washington, D.C., close to the Lincoln Memorial; photo by F.T. Campbell; other nearby elms are also dead

The USDA Forest Service is not the only entity engaged in breeding American elms. The University of Minnesota is supporting an American elm breeding program through its Minnesota Invasive Terrestrial Plants and Pest Center (MITPPC) (see Bernardt citation at end of blog). Scientists are identifying DED-resistant elms in the wild, cloning and testing them, and replanting the strongest candidates across urban and natural landscapes. Their goal is to reintroduce the more resilient clones across Minnesota’s urban and natural landscapes, restoring lost canopy and biodiversity while preparing forests for a future stressed by climate change.

Bernardt describes the usual four essential steps: identification of trees that appear to be resistant; propagation of clones from those trees; growing sufficient numbers of these; and testing them for resistance. The Minnesota program – like many similar programs for breeding the many tree species being killed by non-native pests – ask the public to help in searching for “survivor” trees—American elms that appear to be withstanding Dutch elm disease even as others around them succumb.

The article summarizes the next steps and challenges. It notes, for example, that using clones rather than seedlings is essential because resistance is not reliably passed on during sexual reproduction. (However, Cornelia Pinchot Wilson has told me that colleagues should soon publish articles demonstrating that resistance is heritable.) Furthermore, the clones must be grown for several years—often five or more—until the trees are large enough to be tested for resistance. The article does not indicate whether the earlier step of propagating elm clones is challenging or easy. It has been difficult for other species, e.g., chestnuts, whitebark pine, ash, and koa.

To confirm whether a specific tree is resistant, the team typically tests each tree twice, since environmental factors like location and weather can influence outcomes. Trees that pass these tests move on to the next stage: reintroduction plantings in natural areas and parks. These field-growing trees serve two important roles. First, they contribute to restoring elm populations in natural and urban landscapes. Second, these trees can be observed over the long term to confirm whether they exhibit persistent resistance and are adapted to local environmental conditions.

The project’s success, the researchers say, hinges on collaboration. State agencies, local governments, and community members all play critical roles. Among those helping have been the Minnesota Department of Natural Resources, the Izaak Walton League, and Three Rivers Park District.

The article reminds us that resistance breeding is a long-term process. As noted above, clones must be grown for years before they can be tested.

Also, resistant trees aren’t immune to the pathogen. Instead, they survive despite the disease in sufficient numbers to restore the species to some of its former range and ecological role.

Finally, the trees must also survive the every-day challenges of life as a tree: storms, animal feeding, and other pests and diseases – native and non-native. The article mentions elm yellows disease but not elm zig-zag sawfly which has been moving West (it was detected in Ohio in 2023 and Wisconsin in 2024). Nor does it mention the fungus Plenodomus tracheiphilus, which is killing American elms in Alberta. Breeding program staff can help – for example, the Minnesota program now uses larger protective tubes to better shield the young trees from wildlife.

The Minnesota program plans to establish seed orchards. They hope that by planting trees confirmed to be resistant near to each other, they will cross-pollinate and produce seeds that are more likely to carry resistance, possibly even combining different resistance genes. Trees in these orchards would capture a broad range of resistance traits, helping future generations of elms stand strong against Dutch elm disease.

Program leaders Ryan Murphy and Ben Held also hope new technologies for studying genes will enable discovery of the genetic basis for resistance to DED. Identifying resistance genes or markers would make producing resistant trees a lot easier. It would also enable breeders to build up genetic diversity more deliberately.

SOURCES

Bernhardt, C. 2025. “Reviving a Giant” July 2025. University of Minnesota. Minnesota Invasive Terrestrial Plants and Pest Center. Website?

Knight, K.S., L.M. Haugen, C.C. Pinchot, P.G. Schaberg, & J.M. Slavicek. Undated. American elm (Ulmus americana) in restoration plantings: a review.

Wei, X.; Zhang, J.; Conrad, A.O.; Flower, C.E.; Pinchot, C.C.; Hayes-Plazolles, N.; Chen, Z.; Song, Z.; Fei, S.; Jin, J. Machine Learning-based Spectral and Spatial Analysis of Hyper-and multi-spectral Leaf Images for Dutch Elm Disease Detection and Resistance Screening. Artif. Intell. Agric. 2023, 10, 26–34. https://doi.org/10.1016/j.aiia.2023.09.003.

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

https://fadingforests.org

USFS appropriations – Senate actions

The Senate Appropriations Committee has adopted its bill appropriating funding for the USDA Forest Service for Fiscal Year 2026, which begins on 1 October. Once the bill passes the full Senate, negotiators for the Senate and House committees must agree on a compromise.

The Senate bill provides a total of $8.6 billion for the Forest Service. This includes $308,497,000 for the Research and Development program. This is an increase of $8.5 million above funding for the current year. The Senate bill specifically supports retaining the five regional offices and experimental forests. Remember, the Trump Administration had proposed to eliminate the Research program – other than Forest Inventory and Analysis. The Committee’s report link specifies that the USFS should prioritize projects requested by or benefitting the agency’s mission, not requests by external entities. The benefit to the agency and public should be stated before a project is initiated. The report specifies funding for several issues, including

$3 million to continue collaborative research to determine distribution & movement of the pathogens that cause needle blight on loblolly pine.
Funding to maintain Experimental Forests in the Northeast. These are described as important for assessing the long-term response of eastern white pine & northern hardwoods to various forest management prescriptions, controlled burning & natural factors, such as insects, disease, weather events and climate change. While the wording is somewhat confusing, I believe this is funded at $6 million.
$1 million to support Outbreak Timber Salvage Research related to drought & needle tip blight & Ips beetle outbreaks in the West.
$3 million to support Needle Blight Mitigation collaborative research.
Several program areas related to fire, including understanding the risk in the wildland-urban interface.

Finally, the bill would fund Forest Inventory and Analysis at $32 million.

a white oak in Maryland; photo by Bob Gutowski via Flickr

There is particular attention to white oaks (Quercus alba). The report notes that this species occupies 103 million acres in E U.S. The species is critical for wildlife, biodiversity, & forest products. The Committee instructs the USFS to report on its efforts, including monitoring & research, to regenerate white oak on National forests as well as state, tribal, and private lands. The Committee recognizes importance of seed stock & tree nurseries in these efforts.

The bill also restores funding for the State, Private, and Tribal Forestry program. It provides $319.5 million for this, an increase of $16 million above the current level. Again, the Trump Administration had proposed to eliminate funding for the SPT program. The Senate report specifies that the Cooperative lands forest health management program should be funded at $42 million. However, the Committee also allocated significant proportions of this total to specific projects:

$10 million (nearly a quarter of the total) to support mitigation efforts targeting the spruce budworm outbreak in the eastern US.
$3 million for a Cogongrass Management Pilot Program
$2 million for management of the sudden oak death pathogen in the forests of Oregon and California
Prioritizing – but without specifying funding levels – of the Western Bark Beetle Initiative and helping urban areas restore and improve their forests and combat exotic invasive woody plant species.

There is also $19.6 million to support Congressionally-directed components of Forest Resource Information and Analysis – which is apparently separate from the FIA program.

The Senate bill also continues support for the USFS International Programs.

Under the National Forest System, the Committee instructs the USFS to spend at least $2 million per year on recovery of species of plants and animals listed under the Endangered Species Act. This category includes whitebark pines but not other tree species decimated by non-native pests.

whitebark pine with Clarke’s nutcracker; photo by Walter Siegmund

While I am disappointed that the Senate report makes few reference to non-native pests other than the loblolly needle blight, I rejoice that the Committee explicitly endorses the importance of USFS programs to sustain forest health across all landscapes – not just in National forests – and the Research program’s status as the premier such entity around the world.

Reminder: the House Appropriations bill provides $301,706,000 for the research account – almost $7 million less than the Senate. The House’ allocation for the Forest Inventory and Analysis (FIA) program is $34 million. Thus, there is a $9 million difference in funding levels – a significant challenge to reconcile. How will funding for the already-underfunded invasive species programs fare?

The House bill provides $280,960,000 for the State, Private, and Tribal forestry program. This is $38 million less than the Senate bill. The available report did not specify funding levels for the Forest Health Management program – either the “cooperative lands” or “federal lands” subprograms. As I note above, the Senate bill increases funding for the cooperative lands account, but then earmarks all the increase.

Posted by Faith Campbell

https://fadingforests.org

American Forest Congress calls for “urgent” action to counter forest pests

Eastern deciduous forest – Great Smoky Mountains National Park; photo by F.T. Campbell

Organizers of the American Forest Congress claim the meeting has influenced the direction of forest conservation and management in America since 1882. As examples they cite creation of the U.S. Forest Service, the establishment of the eastern National Forests, new community-based and collaborative approaches to forestry, and efforts to advance the leadership of women within the forest community.

During its meeting in Washington, D.C. in July 2025, the Ninth Forest Congress adopted a resolution re: threat from forest pests and pathogens:

Resolved: to recognize and address the urgent risk posed by exotic and native pests and pathogens and invasive species to long-term health, productivity and sustainability of America’s forests.

Provide adequate and sustained resources for a cooperative stewardship program to monitor and address these risks across landscapes and ownerships.

Convene regional partnerships with participation of state, federal and tribal authorities, private landowners, NGOs, universities and other interested stakeholders to identify key forest health risks, develop regional approaches and attract needed resources to implement and sustain them.

Brian Milakovsky, senior forester at the New England Forestry Foundation helped gather an ad hoc group of forest health experts and foresters from across the eastern seaboard to draft the resolution

The Committee now plans to organize a follow-up event sometime in 2025 to discuss what is needed to build a more diverse and robust funding pipeline for pest and pathogen work. Their concern was elevated by the Trump Administration’s proposal to stop funding for the USFS’ State, Private and Tribal Forestry program.

healthy hemlock forest, Cook Forest State Park, Pennsylvania; photo by F.T. Campbell

The New England Forestry Foundation has a direct stake in these programs. The Foundation manages 41,000 acres of land in five New England states and works with diverse landowners in the region to improve forest management. The Foundation hopes to expand both on-the-ground work and advocacy in response to the threats from non-native insects and pathogens. While they are focusing on developing an IPM program on their own lands, they recognize that they must address the pest and pathogen levels of the surrounding landscape – that is, they wish to support the federal and state forest health experts who are trying to address these issues at the largest scale.

In Maine the Foundations is trying to manage destruction by the hemlock woolly adelgid (HWA), beech bark disease, beech leaf disease, winter moth, red pine scale, and browntail moth. The emerald ash borer is arriving – and threatens to decimate green ash forests covering entire hillsides – with repercussions for water supplies, flooding, etc.

This resolution presents a great opportunity to revive discussions about the non-native forest pest issue with federal and state government officials, fellow conservationists, and the foundations that fund conservation work. Let’s work individually and together to put real muscle into these programs.

One of the possible ways is to persuade Congress to adopt the bill under development by Sen. Peter Welch of Vermont. The bill as introduced in the previous session is available here. Please ask your senators to sponsor it in this session – perhaps as a component of the (overdue) 2024 Farm Bill.

Posted by Faith Campbell

https://fadingforests.org

Funding for key USFS programs – reprieve in House

The House Appropriations Committee, Subcommittee on Interior, adopted its version of appropriations for the USDA Forest Service (USFS) for Fiscal Year 2026, which begins October 1^st. The bill restores the basic funding levels for the Research and Development and State, Private, and Tribal Forestry accounts. (The Trump Administration had called for cutting nearly all funding for these accounts.)

The Subcommittee provides $301,706,000 for the research account. I am having difficulty determining the funding level for the current year (FY25) since the Administration and Congress have taken several contradictory actions. I am disappointed that $34 million of the research total is allocated to the Forest Inventory and Analysis (FIA) program. FIA data inform us about changes in the forest, including damage caused by introduced insects and pathogens. But FIA data do not identify or disseminate information about how such threats might best be countered. I had asked Congress to begin increasing the proportion of research funds allocated to studying the invasive forest pests.

Furthermore, the only other topic of research mentioned in the bill is fire research. I fear that might led to decreased attention to non-fire aspects of introduced tree-killing insects and pathogens – the opposite of what I think is appropriate.

one of numerous risk maps for *Phytophthora ramorum*; many aspects of this pathogen still require research – perhaps especially the likelihood that the three strains present in forests in Oregon & California will reproduce sexually

The Subcommittee provides $280,960,000 for the State, Private, and Tribal forestry program. This is apparently a $23 million cut for the overall SPT program. The bill specifies that this funding “includes forest health management, invasive plants, and conducting international programs and trade activities.” This would seem to restore funding for the Forest Health Management program – both the “cooperative lands” and “federal lands” subprograms. I doubt that the funding will reach the level I suggested: $32 million for the cooperative lands subprogram and $16 million for the federal lands subprogram.

Still, it is a great relief that the Congress has – so far – chosen to maintain these programs, which are so critical to countering invasions by non-native organisms. I hope the full House and the Senate will agree. Please contact your senators and remind them how important these programs are.

(Some other important programs have been sacrificed in the appropriations bill – A 23% cut in the budget for the Environmental Protection Agency; reversing some regulations intended to protect various endangered species …)

Posted by Faith Campbell

https://fadingforests.org

Tree deaths in a National Park – what I saw

In June I visited Shenandoah National Park (SHNP) (above) for the first time in years. The Park’s forests are mostly mature secondary forests, having recovered over the 90 years since establishment from earlier logging and clearing for small-scale farms and pasture.

While I loved the forest and the vistas, I was aware of which species are missing …

Five years ago I blogged about a study by Anderson-Teixeira et al. (full citation at the end of this blog) that reported on the changes in the forests of SHNP and the neighboring Smithsonian Conservation Biology Institute (SCBI). This is important because, as Fei et al. (2019) (full citation at the end of this blog) documented, nine of the 15 most damaging introduced forest pests grow in eastern forests. In fact, the greatest increase in biomass loss has occurred in Eastern forests. Seven are found specifically in SHNP (Potter et al. 2019; full citation at the end of the blog).

Anderson-Teixeira et al. report that non-native forest pests caused a loss of about a quarter of ecosystem above-ground biomass between 1991 and 2013 across 66 sites. These invasions occurred after the worst impacts of chestnut blight, which entered the country ~120 years ago – before “modern” phytosanitary programs were instituted. Still, total above-ground biomass has largely recovered through germination and growth by trees in other genera. Greatest increases have been by tulip poplar (Liriodendron); oaks (Quercus); ash (Fraxinus) – but see below; birch (Betula); and maples (Acer). And while several taxa were lost from monitoring plots in SHNP and SCBI, a-diversity also remained steady.

So what does that look like on the ground?

American chestnut used to dominate many Eastern forests, composing more than one-third of the pollen assemblage in some stands (Fei et al.) According to Anderson-Teixeira et al., chestnut trees larger than 10 cm DBH disappeared by 1910, killed by chestnut blight. In past decades I frequently saw chestnut root sprouts when hiking. The National Park Service now urges visitors to hike to low elevation sections of the South River Trail to see such sprouts.

In the 1980’s, groves of eastern hemlocks occupied about 9,800 acres in SHNP, primarily in shaded valleys and along streams. Invasion by the hemlock woolly adelgid killed 95% of these hemlocks. Anderson-Teixeira et al. document the species’ disappearance from their study plots by 2007. Park staff treated more than 20,000 hemlocks using injections of imidacloprid. In 2015, the Park began partnering with Virginia Polytechnic Institute and State University in releasing predatory biocontrol beetles (Laricobius spp.) While the beetles have shown promising establishment and spread, it is now recognized that additional biocontrol agents will be needed to suppress the adelgid. The Park plans to allow releases of predatory silver flies (Leucotaraxis spp.) in remaining hemlock sites and will begin to phase out the imidacloprid treatments.

I remember the hemlocks! But this year, at least in the creek valleys where I hiked, I saw almost no remnants – not even fallen logs.

fallen hemlock; all photos by F.T. Campbell in Shenandoah NP in June 2025

And I remember the flowering dogwoods. They are almost gone now from the Appalachian chain, killed by dogwood anthracnose. Their status in SHNP is unclear. Anderson-Teixeira et al. report flowering dogwoods only from the Smithsonian property. There, they declined by almost 90% from the study plots from 2008 to 2019. The Park’s list of tree and shrub species reports that flowering dogwood is still “abundant”; my visit was too late in the season to observe how visible flowering dogwoods still are. Certainly the species survives the disease better in open settings, e.g., meadows and roadsides. I don’t know how the three other native Cornus species were affected.

Dead ash are still visible. Ash trees made up about 5% of the Park’s forest cover. Anderson-Teixeira et al. report that ash aboveground biomass was increasing in SHNP and stable on the SBCI property before arrival of the emerald ash borer (EAB). EAB-caused mortality was first detected in 2016. In just three years — by 2019 – 28% of green, white, and black ash had died; this meant a loss of 30% of ashes’ aboveground biomass. Ninety-five percent of remaining live trees were described as “unhealthy’’. In an effort to retain ash trees for visitor enjoyment, reduce threats to visitors from hazard trees, and to preserve a portion of the park’s ash tree communities until host-specific biological controls become available, SHNP staff – supported by specially trained volunteers and interns, Virginia Department of Forestry and Fairfax County – began treating high-value ash with emamectin benzoate. They began at Loft Mountain Campground, a location (elevation 3,300 feet) where ash trees make up most of the forest. Three hundred forty three trees were treated there — exceeding expectations for what could be accomplished in a single year. The park hopes to treat an additional 200-400 trees. They will target ash trees around campgrounds, picnic areas, overlooks and other areas frequently used by visitors. These efforts were supported by the Shenandoah National Park Trust and here.

I saw many dead oaks – probably the result primarily of repeated attacks by the spongy moth link beginning in 1982. Oak-dominated study plots in SHNP lost on average 25% of individuals and 15% of above-ground biomass. After 1995, when spraying of Bacillus thuringiensis var. curstaki improved control efforts (at the expense of native moths), oak aboveground biomass increased gradually, driven by individual tree growth rather than recruitment. Oak abundance continues to decline due to oak decline and absence of management actions to promote regeneration (Anderson-Teixeira et al.). These authors do not mention oak wilt although a decade-old map shows the disease to be present just to the west of the Blue Ridge (visible here).

Fortunately Shenandoah National Park has relatively few American beech, so it will be less affected by beech leaf disease (BLD). The Blue Ridge is also far from large waterbodies — which promote the disease. However, I did see some beech sprouting in creek valleys – probably in gaps opened when the hemlocks died. These valleys with higher humidity are the type of ecosystem most conducive to the disease! Anderson-Teixeira et al. note that they did not analyze the impact of beech bark disease – which was the disease of concern before arrival of BLD and continues to be present.

They also did not evaluate the impacts of balsam woolly adelgid, described as having decimated high-elevation populations of firs (Abies balsamea); white pine blister rust on eastern white pine; or EAB on fringetree (Chionanthus virginicus) in SCBI. Nor did they document the impact of thousand cankers disease (TCD) on walnuts or butternuts. This concerns me because they report that the disease “appears to be affecting Juglans spp. in our plots.” Furthermore, butternut (J. cinera) had been ‘‘common’’ in 1939, but had disappeared from SHNP by 1987. On the Smithsonian property, the four individuals found originally had declined by half – to two living individuals. Butternut has suffered high levels of mortality throughout its range from butternut canker.

The understory tree redbud (Cercis canadensis) also declined precipitously – by almost76% from 1995 to 2018 in SCBI plots. While Anderson-Teixeira et al. do not speculate why, a few years ago a wider decline was reported.

Of course, Shenandoah also has been invaded by non-native plants! So I saw some plants that should not be there. At least the mid- and high-elevations that I visited appear to be much less abundant in the Park than in coastal and piedmont regions of Virgina. Ailanthus is listed as “common” in the Park. I didn’t see Japanese stiltgrass but it is clearly present at lower elevations. I was particularly disturbed to see oriental bittersweet along trails located in all three sections of the Park.

The Blue Ridge PRISM is targeting 12 species: autumn olive, garlic mustard, Japanese honeysuckle, Japanese stiltgrass, kudzu, mile-a-minute, multiflora rose, oriental bittersweet, porcelainberry, privet, tree of heaven, and wavyleaf grass.

SOURCES

Anderson-Teixeira, K.J., V. Herrmann, W.B. Cass, A.B. Williams, S.J. Paull, E.B. Gonzalez-Akre, R. Helcoski, A.J. Tepley, N.A. Bourg, C.T. Cosma, A.E. Ferson, C. Kittle, V. Meakem, I.R. McGregor, M. N. Prestipino, M.K. Scott, A.R. Terrell, A. Alonso, F. Dallmeier, & W.J. McShea. 2021. Long-Term Impacts of Invasive Insects & Pathogens on Composition, Biomass, & Diversity of Forests in Virginia’s Blue Ridge Mountains. Ecosystems

Fei, S., R.S. Morin, C.M. Oswalt, & A.M. Liebhold. 2019. Biomass losses resulting from insect & disease invasions in United States forests. Proceedings of the National academy of Sciences.

Potter, K.M., M.E. Escanferla, R.M. Jetton, G. Man, & B.S. Crane. 2019. Prioritizing the conservation needs of United States tree spp: Evaluating vulnerability to forest insect & disease threats. Global Ecology & Conservation.

Posted by Faith Campbell

https://fadingforests.org

Call for new approach to biological conservation – integrating bioinvasion

whitebark pine in Glacier National Park killed by white pine blister rust

The Kunming-Montreal Global Biodiversity Framework (KMGBF) is a major global policy driver around the world for more effective action to preserve biodiversity from current and future threats. (However, the United States has not joined the underlying treaty, the Convention on Biological Diversity (CBD). So its importance is probably less in the United States than in countries that take part.) This relatively new Framework was adopted at the 15^th Conference of the Parties (COP) of the CBD in December 2022 after four years of negotiations. However, cynics note that the 196 countries that are parties to the CBD have rarely met previous ambitious goals set at earlier COP.

Hulme et al. have just published a paper [full reference at the end of this blog] addressing how invasive species and this Framework’s target may interact. They note that conserving biodiversity costs money. Many of the countries hosting diverse and relatively intact ecosystems lack sufficient resources, capability, or robust governance structures for this conservation.

The Kunming-Montreal Global Biodiversity Framework sets out ambitious global targets to reduce biodiversity loss by 2030 so as to maintain the integrity of ecosystems and their constituent species. Of the 23 targets, one – Target 6 – addresses bioinvasion. Countries endorsing the CBD have committed to eliminating, minimizing, reducing and/or mitigating invasive species’ impacts on biodiversity and ecosystem services. This is to be accomplished by identifying and managing introduction pathways; preventing introduction and establishment of priority invasive species; reducing rates of introduction and establishment of known or potential invasive species by at least 50% by 2030; and eradicating or controlling invasive species, especially in priority sites.

I rejoice that the CBD parties have recognized invasive species as a major driver of biodiversity loss in terrestrial and marine ecosystems. I wish conservation organizations’ and funders’ activities clearly reflect this finding.

This is the challenge raised by Hulme et al.: countries must integrate efforts to counter bioinvasions into overall conservation programs. Success in curbing bioinvasion depends upon achieving almost all other KMGBF targets. And this is a two-way street: the more holistic approach offers greater likelihood of successful biodiversity conservation.

The same authors point out that some of the 22 other targets address rapidly evolving introductory pathways e.g.,

Target 15 – increasing international and domestic tourism;
Target 12 – encroachment of urban areas near protected areas;
Target 10 – development of intensive agriculture or aquaculture systems near protected areas;
Target 7 – species rafting on plastic marine pollutants; and
Target 8 – growing risk from species shifting ranges in response to climate change.

pallet graveyard behind camp store & snack bar art Lake MacDonald, Glacier National Park; photo by F.T. Campbell

Other targets relate to management of established invasive species, e.g.,

Target 1 – planning and priority-setting for allocation of limited resources among the various threats to biodiversity;
Identifying factors that pose risks to highly-valued species, e.g., threatened species (Target 4) and species that provide important ecosystem services (Target 11);
Target 19—obtaining necessary financial resources.

A final group of targets are intended to guide all conservation efforts. These goals include integrating biodiversity concerns in decision-making at every level (Target 14); reducing harmful economic incentives and promoting positive incentives (Target 18); and several targets addressing issues of equity, benefit sharing, and access to information. Hulme et al. assert that the threat posed by bioinvasions must be incorporated into policies, regulations, planning and development processes and environmental impact assessments across all levels of government.

Hulme et al. decry an imbalance as to which KMGBF targets have been the focus of attention from governments, conservation organizations, and media. These stakeholders have concentrated on

Target 3, which calls for extending legal protection to 30% of lands and waters by 2030;
Target 4, which promotes maintaining genetic diversity within and among populations of all species;
Target 7, which encourages reducing harmful pollution;
Target 15, which urges businesses to decrease biodiversity risks arising from their operations; and
Target 21, which advocates ensuring equitable and effective biodiversity decision-making.

Even when stakeholders have looked at Target 6, they have focused primarily on how to quantify the numbers of species being introduced to novel ecosystems. Hulme et al. argue that conservationists should instead concentrate on the challenge of achieving the target. They note that bioinvasion is worsening despite implementation of many long-term management programs. As they note, numbers of introduced species globally have increased, these species are occupying larger geographic areas, and the species’ measured impacts have risen to astounding levels (see my previous blog about new cost estimates). This same point was made two years ago by Fenn-Moltu et al. (2023) [full citation at the end of this blog]; they found that the number of invasive species-related legislation and treaties to which a country adheres did not relate to either the number of insect species detected at that country’s border or the number of insect species that had established in that country’s ecosystems.

As conservationists, Hulme et al. remind us that not all damages are monetary: invasive species threaten more than half of all UNESCO World Heritage Sites.

Hulme et al. say achieving Target 6 presents several scientific challenges – most of which have been discussed by numerous other authors. Introduction pathways are changing rapidly. There is great uncertainty regarding current and especially future propagule pressures associated with various pathways. Information about particular species’ impacts and where they are most likely to be introduced is insufficient. Management costs are routinely underestimated. Perhaps most challenging is the need to judge programs’ effectiveness based not simply on outputs (e.g., number of acres cleared of weeds) but on outcomes in relation to reducing the subsequent impact on biodiversity and ecosystem services.

I note that several environmental organizations endorsed a “platform” that discussed this last point a decade ago. [I have rescued the NECIS document from a non-secure website; if you wish to obtain a copy, contact me directly through the “comment” option or my email.] Unfortunately, the coalition that prepared this document no longer exists. Even when conservation organizations have invasive species efforts, they are no longer attempting to coordinate their work.

I greatly regret that Hulme et al. continue a long-standing misrepresentation of international border biosecurity controls as consisting primarily of inspections — of imported commodities, travellers, and associated transport conveyances. I have argued for decades that inspections are not effective in preventing introductions. See Fading Forests II Chapter 3 (published in 2003); Fading Forests III Chapter 5 (published in 2014); “briefs” describing pathways of introduction prepared for the Continental Dialogue on Non-Native Forest Insects and Diseases – in 2014 and in 2018.

The weaknesses of visual inspection are especially glaring when trying to prevent introductions via wood packaging material and living plants — also here.

Hulme et al. propose a politically astute approach to finding the resources to strengthen countries’ efforts to curtail invasive species’ spread within their borders. Recognizing that no country has unlimited resources to allocate to managing invasive species, they suggest concentrating slow-the-spread efforts on preventing damage to legally protected areas. Furthermore, authorities should avoid designating as new “protected areas” places that are already heavily invaded – or at risk of soon becoming so. As they note, programs aimed at protecting these areas often engage conservation stakeholders, decision-makers, even potential non-governmental donors. In other words, there is a foundation on which to build.

To buttress their argument, Hulme et al. cite evidence that bioinvasions threaten these areas’ integrity. For example, Cadotte et al. (2024) found that bioinvasion is one of most frequently identified threats identified in a survey of 230 World Heritage sites; and that they pose a greater degree of concern than other threats to biodiversity. They reiterate that managing invasive species is one of the most effective interventions aimed at protecting biodiversity.

The task remains complex. Hulme et al. note that accurate information about pressure caused by invasive species is not easily quantified using remote sensing. It requires expensive on-the-ground data collection. Even current methods for ranking invasive species have crucial gaps regarding species’ potential impact and the feasibility of their control. Choosing management strategies also requires assessing potential unintended effects on biodiversity and other GBF Targets, e.g., pollution from pesticides (Target 7).

Still, the context remains: successful management of bioinvasions to support the integrity of protected areas depends on the integrative approach described above.

Hulme et al. note a contradiction within the Kunming-Montreal Global Biodiversity Framework: Target 10 calls for the agriculture, aquaculture, and forestry industries to adopt sustainable practices, but doesn’t raise the issue of these sectors’ role in the introduction and spread of invasive species. They say guidelines have been developed for sustainable forestry production. These guidelines recommend that commercial plantation forests not plant non-native tree species within 10 km of a protected area. Hulme et al. also suggest applying a “polluter pays” fine or bond to forestry businesses that use invasive species without sufficient safeguards to prevent escape. These funds could be accessed to support invasive species management in protected areas, particularly surveillance. (Target 19 mandates obtaining more funds for this purpose). They add that these aquaculture, agriculture, horticulture and forestry sectors should take action to prevent the local feralization of alien crops and livestock.

Target 8 calls for minimizing the impacts of climate change on biodiversity. Hulme et al. note numerous scientific challenges here, including understanding how specific ecosystems’ and native species’ are vulnerable to altered climates, along with how specific invasive species’ are responding to an altered climate regime.

These same authors provide specific recommendations to the global conservation community to put in place a more holistic perspective. Some recommendations deal with data integration. Others call for major undertakings: i.e., developing a protected area management toolkit at a global scale. This action will require significant investment in capacity-building of protected area managers plus international cooperation and technology transfer (Target 20). Hulme et al. suggest funding this effort should be a priority for any resources leveraged from international finance (Target 19).

Hulme et al. also propose changes in the conservation approaches advocated by the CBD and IUCN. Specifically, they call for more explicit consideration of current and future impacts of bioinvasions and their management — on protected areas. The needed activities fall into six areas:

(1) reduce risks associated with various pathways;

(2) plan for range-shifting invasive species;

(3) mitigate invasive species’ impacts on biodiversity and (4) on ecosystem services;

(5) ensure new protected areas (including urban green spaces and infrastructure corridors) are largely free of established (“legacy”) invasive species; and

(6) provide managers sufficient resources to take effective action.

SOURCES

Fenn-Moltu, G., S. Ollier, O.K. Bates, A.M. Liebhold, H.F. Nahrung, D.S. Pureswaran, T. Yamanaka, C. Bertelsmeier. 2023. Global flows of insect transport & establishment: The role of biogeography, trade & regulations. Diversity & Distributions DOI: 10.1111/ddi.13772

Hulme, P.E., Lieurance, D., Richardson, D.M., Robinson, T.B. 2025 Multiple targets of Global Biodiversity Framework must be addressed to manage invasive species in protected areas. NeoBiota 99: 149–170. https://doi.org/10.3897/neobiota.99.152680

Posted by Faith Campbell

https://fadingforests.org

Update: pests spreading … funding stalled …

Oregon ash in swamp in Ankey National Wildlife Refuge, Willamette Valley, Oregon; photo by Wyatt Williams, Oregon Department of Forestry

1) Funds still not released

As of the end of June, the Office of Management and Budget has not released funds to programs under the USDA Forest Service’ State, Private, and Tribal section. This includes many programs – grants, etc. – that support state and other entities’ efforts and operation of the Forest Health Protection program. Meanwhile, tree-killing insects, pathogens, and nematodes pursue their lives … killing trees in the process.

Congress has not yet acted on legislation that will determine the funding level for USFS FHP and Research programs in Fiscal Year 2026, which begins on October 1. I remind you that the Administration has proposed 0 funds for these programs. Take advantage of the Congressional delay – contact your Member of the House and Senators.

2) the Mediterranean oak beetle (MOB) Xyleborus monographus has now been detected in nine California counties, including Napa, Sonoma, Lake, Sacramento, El Dorado, Yolo, Mendocino, and as of last month, Marin. MOB is also present in Oregon – in Multnomah, Clakamass, Marion and Washington counties.

There is no treatment for infected trees. California authorities urge landowners to search for the insect and remove infected trees – and to avoid moving infested wood.

3) Oregon Department of Forestry has announced that thousand canker disease (TCD) of walnut is killing trees of the Juglans genus in the Willamette Valley. Where the insect has been found in traps, the majority of black walnut trees have since died. Black walnut (Juglans nigra) is not native in Oregon; its range east of the Great Plains. Apparently the range of northern California black walnut (Juglans hindsii) also does not extend into Oregon.

Cities in Oregon are preparing for the inevitable arrival of the emerald ash borer (EAB) (Agrilus planipennis) which was detected in Forest Grove in June 2022. The City of Salem inventoried all of its street & park trees in the last 5 years. It plans to inject a systemic pesticide into at least 550 trees this year and a similar number next year. These trees have been judged to be in good condition. Ash trees in poor condition along streets or in parks are gradually being removed and replaced.

Salem also plans to inventory Oregon ash growing in the city’s natural areas so as to understand where they will need to plant other native species. I blogged earlier about the threat EAB and MOB pose to western Oregon’s wetlands and oak savannahs.

4) Ann Hajek of Cornell and colleagues haves published a review of 20 years of research on entomopathogens that might contribute to control efforts targetting the Asian longhorned beetle (ALB) (Anoplophora glabripennis). The authors call for renewed efforts to find appropriate control agents and techniques. They conclude that various pathogens – especially fungi – can support ALB eradication efforts. They would be particularly helpful if ALB populations spread – or a new outbreak is detected. (Remember, ALB has been detected in seven locations in North America – some the result of more than one introduction; and nine locations in Europe.)

The article is open access!! See

Ann E. Hajek, A.E., E.H. Clifton, and L.F. Solter. 2025. Entomopathogens for control of Asian longhorned beetles (Coleoptera: Cerambycidae). Environmental Entomology, XX(XX), 2025, 1–10 https://doi.org/10.1093/ee/nvaf016

Posted by Faith Campbell

Sentinel Gardens – useful tool if microbes scrutinized sufficiently

Northern red oak – one of the species planted in Europe & China as part of sentinel garden project; photo by F.T. Campbell

During the USDA Interagency Forum on Invasive Species, Dr. Eliana Torres Bedoya, from the Bonello lab at Ohio State, provided insights gained from a sentinel garden project operating for the last five years.

The gardens were established in six locations: two in China in the Nanjing area, one each in Italy, Sweden, Ohio, and New Hampshire. The network required collaboration among scientists in several countries, a difficult task in itself. (Jiri Hulcr of the University of Florida has also stressed the importance of mutually beneficial collaborations.)

The focus was on detecting and identifying novel fungal pathogens abroad before they ever enter a country, in an approach called ex patria sentinel plantings. Altogether, 32 tree species were planted in at least one location. For example, Chinese and European tree species were planted in the U.S. to identify potential threats to China and Europe. Conversely, North American species were planted in Europe and China to detect potential threats to the U.S. As noted, the reciprocity is crucial to establishing and maintaining a long-term relationship.

Key information gained to date:

While the scientists isolated several potential pathogens from symptomatic plants, analysis of all plants’ leaf microbiomes showed that asymptomatic plants harbored many more potential pathogens that had not been isolated.

Healthy plants tend to harbor larger and often more diverse microbial communities. This study found that asymptomatic plants supported a significantly more abundant, richer, and taxonomically diverse leaf-associated fungal community than symptomatic plants. Importantly, this pattern pertains also to the subset of taxa classified as potential plant pathogens.

Detection of the full range of fungal pathogens requires that samples must be collected both early and mid-to-late in the growing season because microbes present differ.
Core leaf microbiomes were associated with specific tree species, no matter where they were planted. However, the constituents of the core microbiome were outnumbered by other organisms driven primarily by the location of the planting. This had been expected.

Other contributing factors – in declining order – were geographic location, tree species, season, and host health status. In other words, the phylogenetic relationship.

The drivers of fungal community composition interact in complex ways. For instance, the effect of the plant’s health on pathogenic fungal communities might depend on the host species. This relationship can be further modulated by seasonal variation and geographic context.

European & Asian trees planted in Ohio as part of the sentinel garden program; photo by P (E) Bonello

Implications:

Sentinel gardens can facilitate identification of novel host-pathogen interactions in symptomatic and asymptomatic plants, so they should be adopted / supported by governmental and regional phytosanitary agencies.
The findings demonstrate the need to expand surveillance beyond symptomatic plants – at both sentinel gardens and plant health border inspection stations. Phytosanitary agencies should employ both full microbial community molecular characterization to detect threats in asymptomatic plants and traditional symptom-based approaches. These modern approaches are described in Munck and Bonello 2018 (full reference at end of the blog).
Enrico Bonello (pers. comm.) thinks it is likely that similar context-dependent interactions among host and fungus species, season, and geography also drive disease infection and virulence.

Eliana Torres Bedoya (pers. comm.) clarifies that the leaf microbiome is the community of microorganisms living on and within tree leaves. These microbes can contribute to protecting trees against pathogens, enhance tolerance to environmental stressors such as drought or pollution, and influence how trees interact with their surroundings. Because the composition of the leaf microbiome responds to changes in climate, location, and tree species, it also serves as a valuable indicator of forest health and environmental change.

There are several approaches to studying microbial communities in leaves. One is the traditional, culture-based method, which relies on isolating and cultivating microorganisms on nutrient media. While this approach is effective for recovering fast-growing and easily culturable taxa, it has a major limitation: the vast majority of environmental microbes are not readily culturable under standard laboratory conditions. As a result, full understanding requires use of culture-independent methods. One technique widely used is metabarcoding. This technique involves extracting total DNA from leaf tissue and amplifying a phylogenetically informative genetic marker specific to the microbial group of interest (for example, the internal transcribed spacer (ITS) region for fungi or the 16S rRNA gene for bacteria). The amplified regions are then sequenced using high-throughput sequencing platforms. After a series of processing steps, the sequences are clustered into Amplicon Sequence Variants (ASVs), which represent unique DNA sequences that can be used as proxies for microbial taxa present in the sample. Torres Bedoya and Bonello used the ASVs for comparative analysis.

*Tilia cordata* (linden) via Picaryl (seed wings make a great tea!)

In her presentation, Torres Bedoya provided examples of the complexities arising when trying to detect fungi associated with trees. Eleven potentially pathogenic fungal genera were found to be more abundant in asymptomatic Northern red oak (Quercus rubra) trees (a North American species) planted in both Europe and China. Five ASVs were more abundant in asymptomatic Fraxinus mandshurica trees (an Asian species) planted in Sweden. In this case, the season when the leaves were sampled explained a higher proportion of the variance in the community composition than did the health status of the host. Molecular methods detected 10 genera not revealed through isolation from little-leaf linden species (Tilia cordata) trees (a European species) planted in China and the US.

This “proof of concept” study considered only fungi associated with leaves. As shown above, learning the true plant health risk associated with any tree taxon’s leaves is already complicated and resource-demanding. To fully exploit the power of the ex patria sentinel plantings approach, phytosanitary officials must provide additional resources (land, people, equipment, money) to enable screening of all plant parts, above and below-ground, and all potentially pathogenic taxa, including nematodes, phytoplasmas, and viruses. These systems must be maintained over years.

Reference

Munck, I.A., Bonello, P. 2018. Modern approaches for early detection of forest pathogens are sorely needed in the United States. Forest Pathology 48 (5). doi:10.1111/efp.1445

Posted by Faith Campbell

www.fadingforests.org

Invasive species cost more than extreme weather attributable to climate change; 17 times more than previously estimated!

ash tree killed by emerald ash borer; photo courtesy of (then) Mayor of Ann Arbor John Hieftje

Since the 1990s, scientists have been trying to the determine costs imposed by invasive species. They hope that measuring monetary costs will motivate political decision-makers to take more assertive actions to counter this ecological treat. As Daigne et al. (2021) point out, too few countries are implementing effective control and mitigation strategies. They say this inaction stems, largely, from undervaluing bioinvasions’ impacts by the general public, stakeholders and decision-makers.

A major step in this effort was creation of the InvaCost database. The goal was to provide a reliable, comprehensive, standardized and easily updatable synthesis of bioinvasions’ monetary costs worldwide.

Several publications based on this database appeared. I have blogged about studies published in 2021 or 2022: a) the costs of bioinvasions generally (Cuthbert et al. 2022); b) the costs imposed by invasive species in protected areas (Moodley et al. 2022; c) a focus on the “worst” 100 invasives (as determined by the IUCN) (Ahmed et al. 2022); and d) assessing costs associated with various pathways of introduction (Turbelin et al. 2022).

The InvaCost database, as applied in these studies, demonstrated that bioinvasions impose tremendous costs –a minimum of US $1.288 trillion for the period 1970 – 2017. These costs increased on average three times per decade (Daigne et al. 2022).

Still, everyone has recognized that InvaCost data have significant limitations. First, three-quarters of the records in the original database came from North America, Oceania and Europe; and referred to animal taxa, even though plants are a major group of invaders. Also, a large proportion of total invasion costs – for all taxa – probably is undetected. Finally, the many non-market values of species and ecosystems are extremely difficult to calculate (Daigne et al. 2022).

As a result of these deficiencies, the earlier studies discussed in the blogs referenced above substantially underestimated the true costs associated with bioinvasion (Cuthbert et al. 2022).

Now a new study, led by Ismael Soto, finds that the underestimate is huge. Global costs associated with a subset of 162 species (17% of all the species in the InvaCost database) is nearly 17 times higher than reported in the InvaCost database.

Soto et al. (2025) applied species distribution models and macroeconomic data to interpolate these 162 species’ probable impacts in 172 countries

Japanese knotweed – one of the invasive plants proving very costly in Europe, according to I. Soto

The newly identified costs were greatest in Europe; second place fell to North America. This is because both higher damage costs and management expenditures are linked to higher gross domestic product and extent of agricultural area, in addition to environmental suitability. Analysis of monetary costs per unit area revealed that ‘cost hot spots’ are predominantly located in densely populated urban areas and locations hosting key industries. These tend to be in coastal zones, i.e., Europe, the east coast of China, and the east and west coasts of the US.

cypress aphid *Cinara cupressi* – a threat to both native & plantation trees in Africa; photo by Blackman & Eastop via Wikimedia

The authors found that the greatest increase in estimated costs for countries in Africa and Asia. These countries had not previously recorded any economic costs arising from invasions by these 162 species. I have blogged about forest pest threats in Africa.

The authors also significantly increased estimated costs linked to invasive plants. Daigne et al. found that invasive insects caused ~90% of reported costs in the InvaCost database as of 2022. Vertebrates ranked second, plants third. In contrast, Soto et al. determined that invasive plants had the highest average estimated damage costs (US $42.10 billion) and management expenditures ($0.81 billion).

Substantial total costs were also reported for arthropods, mammals and birds. Reported damage and management costs were much lower for molluscs, fish, reptiles and amphibians. Daigne et al. suggest this might be due to their lower (observable) damage to human infrastructure, research biases leading to fewer studies, or disparities resulting from the filtering process used in their own study.

Williams et al. (2023) focus on insects, which cause damage primarily to agriculture, human health, and forestry. Insects constitute the highest number of species introduced as ‘Contaminants’ (n = 74) and ‘Stowaways’ (n = 43). They also impose the highest costs among species using these two pathways.

Forest insects and pathogens account for less than 1% of the records in the InvaCost database. I believe that this figure reflects significant under-reporting of these invasion events. Even at this paltry level of reported invasions, forest insects and pathogens were responsible for causing 25% of total annual costs ($43.4 billion) (Williams et al. 2023). This discrepancy illustrates the huge economic cost associated with widespread mortality of trees. Yet authorities in most countries continue to provide completely inadequate resources to counter this threat.

The authors of these publications examining economic losses associated with bioinvasion all note that ecological damage is additional. Soto et al. note that bioinvasions contribute to 60% of already recorded global extinctions. Interestingly, the species ranked third using the criterion of monetary damage is the cactus moth Cactoblastis cactorum. This insect threatens flat-padded Opuntia cacti across the United States and in the center of endemism, Mexico.

a flat-padded *Opuntia* — vulnerable to the cactus moth; photo by F.T. Campbell

Soto et al. found a lag of ~46 years between first (reported) detection of an introduced species and the peak of damage costs. They suggest that the rising monetary cost reflects the species becoming more abundant or occupying a larger area. The authors also say this finding demonstrates the value of implementing mitigation measures as soon as possible. Their finding thus validates others’ advocacy for investing in prevention and rapid response measures (see Cuthbert et al. and Daigne et al.). Soto et al. were cheered by the fact that spending on management measures – when it was reported – often followed soon after a species’ detection – or even before (e.g., prevention).

But Decision-Makers Usually Delay – Why?

Prevention is a hard sell. Decision-makers find it difficult to justify management expenditures before impacts become obvious. By that time, of course, management of the invasion is extremely difficult and expensive – if it is possible at all. Ahmed et al. found particularly effective wording to describe this problem: bioinvasion costs can be deceitfully slow to accrue, so policy makers don’t appreciate the urgency of taking action. Another contributing factor is that when efficient proactive management succeeds in preventing any impact, it paradoxically undermines evidence of the value of this action!

Programs to minimize the economic and ecological consequences of bioinvasion are severely obstructed – if not doomed! – by the following difficulties:

Resources are in short supply. Experts find that demands to address other threats to agriculture or natural systems outcompete appeals to ramp up invasive species efforts.
Prediction is uncertain. Cuthbert et al. found that none of the species with the highest pre-invasion investment was among the top 10 costliest invaders in terms of damages. Cuthbert et al. do not discuss whether this is evidence that the prevention efforts were effective? Or, alternatively, that prevention efforts target the wrong species.
Harm is in the eye of the beholder. Stakeholders’ perceptions of whether an introduced species causes a detrimental impact vary. For example, Moodley et al. point out that species imposing the highest economic costs might not be the ones causing the greatest ecological harm.
Externalities. Those harmed by a bioinvasion often are different from those that decide whether to act. Ahmed et al. argue that this creates a moral dilemma.

These decisions are political — influenced by citizens’ expressed wishes. Changing decision-makers’ perceptions of what is important is up to us!!! Start a parade!!!

SOURCES

Ahmed, D.A., E.J. Hudgins, R.N. Cuthbert, .M. Kourantidou, C. Diagne, P.J. Haubrock, B. Leung, C. Liu, B. Leroy, S. Petrovskii, A. Beidas, F. Courchamp. 2022. Managing biological invasions: the cost of inaction. Biol Invasions (2022) 24:1927–1946 https://doi.org/10.1007/s10530-022-02755-0

Cuthbert, R.N., C. Diagne, E.J. Hudgins, A. Turbelin, D.A. Ahmed, C. Albert, T.W. Bodey, E. Briski, F. Essl, P. J. Haubrock, R.E. Gozlan, N. Kirichenko, M. Kourantidou, A.M. Kramer, F. Courchamp. 2022. Bioinvasion costs reveal insufficient proactive management worldwide. Science of The Total Environment Volume 819, 1 May 2022, 153404

Diagne, C., B Leroy, A-C. Vaissière, R.E. Gozlan, D. Roiz, I. Jaric, J-M. Salles, C.A. Bradshaw, and F. Courchamp. 2021. High and rising econ costs of bioinvasions worldwide Published online: 31 March 2021

Moodley, D., E. Angulo, R.N. Cuthbert, B. Leung, A. Turbelin, A. Novoa, M. Kourantidou, G. Heringer, P.J. Haubrock, D. Renault, M. Robuchon, J. Fantle-Lepczyk, F. Courchamp, C. Diagne. 2022. Surprisingly high economic costs of bioinvasions in protected areas. Biol Invasions. https://doi.org/10.1007/s10530-022-02732-7

Soto, I., P. Courtois, A. Pili, E. Tordoni, E. Manfrini, E. Angulo, C. Bellard, E. Briski, M. Buric, R.N. Cuthbert, A. Kouba, M. Kourantidou, R.L. Macêdo, B. Leroy, P.J. Haubrock, F. Courchamp and B. Leung. 2025. Using species ranges and macroeconomic data to fill gap in costs of biological invasions. Nat Ecol Evol doi: 10.1038/s41559-025-02697-5

Turbelin, A.J., C. Diagne, E.J. Hudgins, D. Moodley, M. Kourantidou, A. Novoa, P.J. Haubrock, C. Bernery, R.E. Gozlan, R.A. Francis, F. Courchamp. 2022. Introduction pathways of economically costly invasive alien spp. Biol Invasions (2022) 24:2061–2079 https://doi.org/10.1007/s10530-022-02796-5

Williams, G.M., M.D. Ginzel, Z. Ma, D.C. Adams, F.T. Campbell, G.M. Lovett, M. Belén Pildain, K.F. Raffa, K.J.K. Gandhi, A. Santini, R.A. Sniezko, M.J. Wingfield, and P. Bonello. 2023. The Global Forest Health Crisis: A Public Good Social Dilemma in Need of International Collective Action. Annual Review of Phytopathology Vol. 61, 2023

Posted by Faith Campbell

www.fadingforests.org

USFS programs “0’d out” in Administration’s budget – please help!

In early May I posted a blog about the Trump Administration’s proposed budget – saying that it would eliminate funding for nearly all USFS research & Forest Health Protection.

I can now provide some additional information.

The Administration has released a supplemental document providing a few details about the severe cuts it is proposing for USFS programs vital to countering bioinvasion in the coming fiscal year (FY2026), which starts October 1^st. You can download this document at https://www.whitehouse.gov/wp-content/uploads/2025/05/appendix_fy2026.pdf

Congress has the final say on appropriations – so please!!! inform your representative & senators about why these cuts are disastrous.

USFS [See pages 162-168 of the Appendix]

Research & Development

The Administration requests $0 for R&D. It says it will strategically use existing carryover balances to responsibly terminate research programs & close research stations. Thus, funding for R&D will decrease from the $301 million in FY24 to $44 million in FY26. The Forest Inventory & Analysis will be shifted to the National Forest System and funded at $21.5 million – less than program supporters are seeking.

The proposal does contain an “additional amount” of $26 million for dealing with the consequences of wildfires, hurricanes & other natural disasters that occurred in calendar years 2022, 2023, and 2024. I am confused about this funding.

State, Private, and Tribal Forests

The Administration requests $0 for S,P&T. Again, the proposal says the agency will use existing carryover balances to effectively & responsibly terminate these programs. The number of employees would be cut from 520 employees in FY24 to 37.

Again, the proposal contains an “additional amount” of $208 million for Forest Health Management to deal with the consequences of wildfires, hurricanes & other natural disasters that occurred in calendar years 2022, 2023, and 2024. $14 million of this sum is earmarked for assistance to states in the Northeast that are anticipating an outbreak of eastern spruce budworm (which has been spreading from Canada). In a highly unusual move, the proposal says this funding is not subject to a requirement that grant recipients provide matching funds from non-federal sources. [Is it a coincidence that Maine Senator Susan Collins chairs the Senate Appropriations Committee?]

National Forest System

Total funding for NFS would be $1.5 billion. This includes an “additional amount” of nearly $2.5 billion for expenses related to the consequences of wildfires, hurricanes & other natural disasters that occurred in calendar years 2022, 2023, and 2024. $75 million of this amount is earmarked for construction or maintenance of shaded fuel breaks in the Pacific Northwest.

As I noted above, the Forest Inventory and Analysis program would be placed under the NFS.

I am particularly concerned that the budget proposal provides explicitly for $20 million to improve or maintain landscape & watershed conditions by preventing invasive plant infestations and installing aquatic organism passages, etc. There is no mention of programs intended to address damage caused by non-native insects and pathogens. It appears that the Administration proposes to drop all programs re: these organisms.

The overall objective of NFS programs is defined as managing the forests for productive use & resilience to catastrophic wildfire & provide broad range of ecosystem services. The budget allegedly prioritizes funding of programs designed to increase health & resilience of National Forests & Grasslands – including meeting multiple use requirements for resources on these lands.

The prose no longer says that timber production is the sole purpose of Nation forests – as the original budget stated.

APHIS appears to have survived – although the supplement provides minimal information (on pp. 85 – 87 of the Appendix).

The supplement contains a lengthy description of APHIS’ purpose — to protect America’s agricultural and natural resources from introduced pests. It requests $1.1 billion for FY2026. The only plant pest listed as a priority is exotic fruit flies. Personnel would be cut from 6,142 in FY24 to 5,092. I could find no specifics regarding funding for programs of interest – tree & wood pests, specialty crops, pest detection, and methods development.

Implications for Non-native Insects and Pathogens

Remember that USFS’s research and development program is intended to improve forest managers’ understanding of ecosystems, including human interactions and influences, thereby enabling improvements to the health and use of our Nation’s forests and grasslands. Most importantly to me, this program provides foundational knowledge needed to develop effective programs to prevent, suppress, mitigate, and eradicate the approximately 500 non-native insects and pathogens that are killing America’s trees.

The Forest Health Program provides technical and financial assistance to the states and other forest-management partners to carry out projects (designed based on the above research) intended to prevent, suppress, mitigate, and eradicate those non-native insects and pathogens. The program’s work on non-federal lands is crucial because introduced pests usually start their incursions near cities that receive imports (often transported in crates, pallets, or imported plants).

[FIA might inform all about where such pests are found — but it doesn’t address how to contain their spread, suppress their impacts, or restore the affected tree species.]

Eliminating either or both programs will allow these pests to cause even more damage to forest resources – including timber.

Both supporting research and on-the-ground management must address pest threats across all U.S. forests, including the more than 69% that are located on lands managed by others than the USFS. Already, the 15 most damaging of these pests threaten destruction of 41% of forest biomass in the “lower 48” states. This is a rate similar in magnitude to that attributed to fire (Fei et al. 2019). [This estimate does not include loss of beech beech leaf disease.] It is ironic that the Administration considers the fire threat to be so severe that it has proposed restructuring the government’s fire management structure.

I remind you that the existing USFS R&D budget allocates less than 1% of the total appropriation to studying a few of the dozens of highly damaging non-native pests. I have argued that this program should be expanded, not eliminated. Adequate funding might allow the USFS to design successful pest-management programs for additional pests (as suggested by Coleman et al.).

As a new international report (FAO 2025) notes, genetic resources underpin forests’ resilience, adaptability, and productivity. Funding shortfalls already undercut efforts to breed trees able to thrive despite introduced pests and climate change (the latter threat is still real, although the Administration disregards it). I have frequently urged the Congress to increase funding for USFS programs – which are sponsored primarily by the National Forest System and State, Private, and Tribal, although some are under the R&D program.

I repeat: Please ask your Member of Congress and Senators to oppose these proposed cuts. Ask them to support continued funding for both USFS R&D and its State, Private, and Tribal Programs targetting non-native insects and pathogens. America’s forests provide resources to all Americans – well beyond only timber production and they deserve protection.

Contacting your Representative and Senators is particularly important if they serve on the Appropriations committees.

House Appropriations Committee members:

Republicans: AL: Robert Aderholt, Dale Strong; AR: Steve Womack; AZ: Juan Ciscomani; CA: Ken Calvert, David Valadao, Norma Torres; FL: Mario Diaz-Balart, John Rutherford, Scott Franklin; GA: Andrew Clyde; ID: Michael Simpson; IA: Ashley Hinson; KY: Harold Rogers; LA: Julia Letlow; MD: Andy Harris; MI: John Moolenaar; MO: Mark Alford; MS: Michael Guest; MT: Ryan Zinke; NC: Chuck Edwards; NV: Mark Amodei; NY: Nick LaLota; OH: David Joyce; OK: Tom Cole, Stephanie Bice; PA: Guy Reschenthaler TX: John Carter, Chuck Fleishmann, Tony Gonzales, Michael Cloud, Jake Ellzey; UT: Celeste Maloy; VA: Ben Cline; WA: Dan Newhouse; WV: Riley Moore

Democrats: CA: Pete Aguilar, Josh Harder, Mike Levin; CT: Rosa DeLauro; FL: Debbie Wasserman Schultz, Lois Frankel; GA: Sanford Bishop; HI: Ed Case IL: Mike Quigley, Lauren Underwood; IN: Frank Mrvan; MD: Steny Hoyer, Glenn Ivey; ME: Chellie Pingree; MN: Betty McCollum; NJ: Bonnie Watson Coleman NY: Grace Meng, Adriano Espaillat, Joseph Morelle; NV: Susie Lee; OH: Marcy Kaptur; PA: Madeleine Dean; SC: James Clyburn; TX: Henry Cuellar, Veronica Escobar; WA: Marie Gluesenkamp Perez; WI: Mark Pocan

Senate Appropriations Committee members:

Republicans: AK: Lisa Murkowski; AL: Katie Britt; AR: John Boozman (AR); KS: Jerry Moran; KY: Mitch McConnell; LA: John Kennedy; ME: Susan Collins; MS: Cindy Hyde-Smith; ND: John Hoeven; NE: Deb Fischer; OK: Markwayne Mullin; SC: Lindsey Graham; SD: Mike Rounds TN: Bill Hagerty; WV: Shelley Moore Capito;

Democrats: CT: Chris Murphy; DE: Chris Coons; GA: Jon Ossof; HI: Brian Schatz; IL: Richard Durbin; MD: Chris van Hollen; MI: Gary Peters; NH: Jeanne Shaheen; NM: Martin Heinrich; NY: Kirsten Gillibrand; OR: Jeff Merkley; RI: Jack Reed; WA: Patty Murray; WI: Tammy Baldwin

Addendum

Maintaining the USFS State, Private, and Tribal (SPT) programs is essential to

complying with laws adopted by the Congress (see second page).
meeting the USFS mission of sustaining “the health, diversity, and productivity of the nation’s forests and grasslands to meet the needs of present and future generations.”
ensuring future economic and ecological benefits to Americans.

More than two-thirds of U.S. forests are privately owned or managed by state, local, or tribal governments. These forests provide many benefits, including 89% of America’s timber harvest.[i] SPT is the only federal program providing technical, financial, & educational assistance to these non-federal landowners.

Among the many threats to American forests, the Center for Invasive Species Prevention (CISP) focuses on the threat from insects and pathogens introduced from abroad. More than 41% of forest biomass in the “lower 48” states is at risk to non-native pests already established in the country.[ii] From 2011 to 2020, sap feeders, e.g., hemlock woolly adelgid, killed trees on 635,000 acres; foliage feeders, e.g., spongy moth, killed trees on 948,884 acres.[iii] Additional pests will be introduced and kill more trees.

Non-native pests are introduced primarily in crates, pallets or other packaging made of wood; and in imported plants. These imports – and the pests – usually land in cities or suburbs and establish there. Initially they cause widespread death of urban trees and impose high costs on local governments and property owners who must remove dying trees. The pests also spread. Hemlock woolly adelgid, emerald ash borer, polyphagous and Kuroshio shot hole borers, goldspotted oak borer, sudden oak death, and beech leaf disease have all spread to National forests from cities or suburbs.

The most effective way to protect America’s forests is to find and kill the pests where they first appear – usually in city trees. Waiting to act until a pest reaches National Forest boundaries means failure. Instead, we should expand the Forest Health Management (FHM) Cooperative Lands program to quickly detect, contain, and – if possible – eradicate the pests. With higher appropriations, the STP FHM program could tackle more of the 53 tree species under threat. At present, only four of these species benefit from 95% of FHM projects – eastern oaks, loblolly and ponderosa pines, and hemlocks.[iv]

USFS Research and Development (R&D) program

FHM adopts strategies based on knowledge of pests’ life histories and traits gained through research conducted or sponsored by the USFS R&D program. CISP urges you to support continued funding for the USFS Research and Development (R&D) program. However, we advocate a realignment: raise the proportion of research funding allocated to invasive species from the current paltry level of 1% to 5%. Funding for studying non-native pests has decreased 70% since FY2010 despite new pests attacking our forests. As a result, the Forest Service is hampered from developing effective programs to prevent, suppress, and eradicate most non-native pests.

Another crucial strategy for reducing loss of tree species to non-native pests is breeding trees able to thrive despite introduced pests. Currently these projects are supported – inadequately – by all three USFS divisions: R&D, SPT, and National Forest System (NFS).

The model program is the Dorena Genetic Resource Center. The Center has bred Western white pine and Port-Orford-cedar trees resistant to introduced pathogens; these trees are now being planted. Promising projects target the pathogens killing whitebark pine, American chestnut, American elm, and Hawaiian koa. Projects at earlier stages address ash, beech, and ʻōhiʻa.

Lesson: federal dollars, wisely invested, can mitigate the damage caused by invasive species. CISP asks you to support continuing these programs so that America can restore threatened trees to our forests.

Complying with the Law

The Cooperative Forestry Assistance Act of 1974

Section 2 (a) Findings …—

(1) most of the productive forest land of the United States is in private, State, and local governmental ownership, and the capacity of the United States to produce renewable forest resources is significantly dependent on such non-Federal forest lands;

(b) Purpose.—… authorize[s] the Secretary …, with respect to non-Federal forest lands … to assist in—

…

(3) the prevention and control of insects and diseases affecting trees and forests;

(c) Priorities.—In allocating funds … , the Secretary shall focus on the following national private forest conservation priorities, …:

…

(2) Protecting forests from threats, including … invasive species, insect or disease outbreak, … and restoring appropriate forest types in response to such threats.

(e) Policy. … it is in the national interest for the Secretary to work through and in cooperation with State foresters, or equivalent State officials, nongovernmental organizations, and the private sector …

Healthy Forests Restoration Act of 2003

Sec. 401(a) FINDINGS.—(1) high levels of tree mortality resulting from insect infestation (including the interaction between insects and diseases) may result in — (A) increased fire risk; … (E) degraded watershed conditions; (F) increased potential for damage from other agents of disturbance, including exotic, invasive species; and (G) decreased timber values;

…

(3) the hemlock woolly adelgid is— (A) destroying streamside forests throughout the midAtlantic and Appalachian regions; (B) threatening water quality and sensitive aquatic species; and (C) posing a potential threat to valuable commercial timber land in northern New England;

(4)(A) the emerald ash borer … has quickly become a major threat to hardwood forests …; and (B) … threatens to destroy more than 692,000,000 ash trees in forests in Michigan and Ohio alone, and between 5 and 10 percent of urban street trees in the Upper Midwest;

…

(11)(A) often, there are significant interactions between insects and diseases; (B) many diseases (such as white pine blister rust, beech bark disease, and many other diseases) can weaken trees and forest stands and predispose trees and forest stands to insect attack; and (C) certain diseases are spread using insects as vectors (including Dutch elm disease and pine pitch canker); …

(b) … The purposes of this title are— (1) to require the Secretary to develop an accelerated basic and applied assessment program to combat infestations by forest-damaging insects and associated diseases; (2) to enlist the assistance of colleges and universities …, State agencies, and private landowners to carry out the program; and (3) to carry out applied silvicultural assessments.

Sec. 402 Definitions

…

(3) FOREST-DAMAGING INSECT. … means … (D) a gypsy moth; (E) a hemlock woolly adelgid; (F) an emerald ash borer; … and (I) such other insects … identified by the Secretary.

[i] Oswalt, S.N., .W.B. Smith, P.D. Miles, & S.A. Pugh. Forest Resources of the United States, 2017 Uport WO-97SDA Forest Service Gen. Tech. Report WO-97. March 2019

[ii] Fei, S., R.S. Morin, C.M. Oswalt, and A.M. 2019. Biomass losses resulting from insect and disease invasions in United States forests. PNAS August 27, 2019. Vol. 116 No. 35 17371–17376

[iii] Coleman, T.W, A.D. Graves, B.W. Oblinger, R.W. Flowers, J.J. Jacobs, B.D. Moltzan, S.S. Stephens, R.J. Rabaglia. 2023. Evaluating a decade (2011–2020) of integrated forest pest management in the United States. Journal of Integrated Pest Management, (2023) 14(1): 23; 1–17

[iv] Ibid.

Posted by Faith Campbell