Invasive “hot spot” study confirms vulnerable places, causes of introductions

removing Miconia from Hawaiian forest; courtesy of the Nature Conservancy of Hawai`i

A recent article by Wayne Dawson and 24 coauthors (see reference at the end of this blog) provides the first-ever global analysis of established alien species. They studied the diversity of established alien species belonging go eight taxonomic groups – amphibians, ants, birds, freshwater fish, mammals, reptiles, spiders and vascular plants – across 609 regions (186 islands or archipelagos, and 423 mainland regions).

The analysis found that the highest numbers of established alien species in these taxonomic groups were in the Hawaiian Islands, New Zealand’s North Island and the Lesser Sunda Islands of Indonesia. The Hawaiian Islands have high numbers of invasive species in all of the eight groups studied. In New Zealand, the highest numbers were invasive plants and introduced mammals that prey on the native birds.

Florida is the top hotspot among mainland regions. Florida is followed by the California coast and northern Australia.

Burmese python in the Florida Everglades; photo by U.S. Fish & Wildlife Service


 Invasive species hotspots were found mainly on islands and in coastal regions of mainland areas. The lead author, Dr. Wayne Dawson, a researcher at Durham University’s Department of Biosciences, suggested that the greater invasive species richness in coastal regions probably results from higher rates of species introductions to port areas compared to interior regions.

Island regions have, on average, higher cross-taxon invasive species richness. This cross-taxon richness on islands tends to be higher for those islands further from continental landmasses. The authors suggest that such oceanic islands might be more likely to import large quantities of goods from foreign sources than islands close to continents, thus experiencing higher propagule pressure.



Regions with greater wealth (measured as per capita GNP), human population density, and area have higher established alien richness. These effects were strongest on islands. The authors suggest that wealth and human population density might correlate with higher numbers of species being brought to the region through trade and transport.

On mainlands, cooler regions have higher richness. I think this might reflect history – centuries of colonial powers importing plants and animals. However, colonial powers also introduced species to tropical regions.  In contrast, on islands warmer and wetter regions have higher richness of invasive species.



The authors conclude that cumulative numbers of invasive species at a particular location are driven to a greater extent by differences in area and propagule pressure than by climate. The model that best explains cross-taxon invasive species richness combines per capita GDP, population density and sampling effort. Other important factors are area of the region, mean annual precipitation, and whether a region is on a mainland or island(s).

The study results show that, per unit increase in area, per capita GDP, and population density, invasive species richness increases at a faster rate on islands than on mainlands. This might be confirmation of the longstanding belief that islands are more readily invaded than mainlands, although the authors caution that a rigorous test of this explanation would require data on failed introductions.

The authors call for additional research to understand whether these effects arise because more species are introduced to hotspot regions, or because human disturbance in these regions makes it easier for the newcomers to find vacant spaces and opportunities to thrive.


I think it would be helpful to compare the findings on invasive species richness in specific regions to data on historic patterns of trade and colonization to strengthen our understanding of the importance of propagule pressure in determining invasion patterns.


Increasing Confirmation of Significance and Breadth of Invasive Species Threat

The Dawson et al. study is the latest in a series of analyses of global or regional patterns in invasive species. I have blogged previously about several of these:

  • Bradshaw et al. 2016 concluded that invasive insects alone cause at least $77 billion in damage every year, a figure they described as a “gross underestimate”.
  • A study by Hanno Seebens and 44 coauthors showed that the rate of new introductions of alien species has risen rapidly since about 1800 – and shows no sign of slowing down. Adoption of national and international biosecurity measures have been only partially effective, failing to slow deliberate introductions of vascular plant species, birds, and reptiles, and accidentally introduced invertebrates and pathogens. Like Dawson et al, Seebens et al. found a strong correlation between the spread of bioinvaders introduced primarily accidentally as stowaways on transport vectors or contaminants of commodities (e.g., algae, insects, crustaceans, molluscs and other invertebrates) and the market value of goods imported into the region of interest.
  • Liebhold et al. 2016(see reference below) studied insect assemblages in 20 regions around the world. They found that an insect taxon’s ability to take advantage of particular invasion pathways better explained the insect’s invasion history than the insects’ life-history traits. (The latter affect the insect’s ability to establish in a new ecosystem.)
  • Maartje J. Klapwijk and several colleagues note that growing trade in living plants and wood products has brought a rise in non-native tree pests becoming established in Europe. The number of alien invertebrate species has increased two-fold since 1950; the number of fungal species has increased four-fold since 1900.
  • Jung et al. (2015) studied the presence of Phytophthora pathogens in nurseries in Europe. They found 59 putatively alien Phytophthora taxa in the nurseries. Two-thirds were unknown to science before 1990. None had been intercepted at European ports of entry when they were introduced. Nor have strict quarantine regulations halted spread of the quarantine organism ramorum.
  • A report by The World Conservation Union (IUCN) on World Heritage sites globally found that invasive species were second to poaching as a threat to the sites’ natural values. Of 229 natural World Heritage sites examined, 104 were affected by invasive species. Island sites – especially in the tropics – were most heavily impacted.
  • Another report by IUCN found that invasive species were the second most common cause of species extinctions – especially for vertebrates.


These studies demonstrate that

  • Invasive species have become a significant threat to biological diversity and ecosystem services around the world – one that continues to grow.
  • The recent spate of studies originating in Europe probably reflects recent recognition of the continent’s vulnerability – as seen, inter alia, in the proliferation of tree-killing Phytophthoras.
  • Human movement of species – propagule pressure – whether deliberately or due to inadequate efforts to manage trade-related pathways – explain the bulk of “successful” introductions.
  • Economic activity drives introductions, so areas at highest immediate risk are urban areas and other centers receiving high volumes of imports and visitors. Among troubling trends in the future is rapid global urbanization – along with rising economic interdependency.
  • Efforts to curb these movements – at the national, regional, and international levels – have failed so far to counter the threat posed by invasive species of nearly all taxonomic groups.

In my view, the requirements that phytosanitary measures “balance” pest prevention against trade facilitation results in half measures being applied – and half measures achieve halfway results. For example, the U.S. does not require that packaging be made from materials that cannot transport tree-killing pests. The USDA has moved far too slowly to limit imports of plant taxa that pose a risk of either being invasive themselves or of transporting pests known to be damaging.


Conservationists should focus on building political pressure to strengthen regulations and other programs intended to curtail this movement. No other approach will succeed.



Bradshaw, C.J.A. et al. Massive yet grossly underestimated global costs of invasive insects. Nat. Commun. 7, 12986 doi: 10.1038/ncomms12986 (2016). (Open access)

Dawson, W., D. Moser, M. van Kleunen, H. Kreft, J. Perg, P. Pyšek, P. Weigelt, M. Winter, B. Lenzner, T.M. Blackburn, E.E. Dyer, P. Cassey, S.L. Scrivens, E.P. Economo, B. Guénard, C. Capinha, H. Seebens, P. García-Díaz, W. Nentwig, E. García-Berthou, C. Casal, N.E. Mandrak, P. Fuller, C. Meyer and F. Ess. 2017. Global hotspots and correlates of IAS richness across taxon groups. Nature Ecology and Evolution Vol. 1, Article 0186. DOI: 10.1038/s41559-017-0186 |


Jung,T., L. Orlikowski, B. Henricot, P. Abad-Campos, A.G. Aday, O. Aguin Casa, J. Bakonyi, S.O. Cacciola, T. Cech, D. Chavarriaga, T. Corcobado, A. Cravador, T. Decourcelle, G. Denton, S. Diamandis, H.T. Doggmus-Lehtijarvi, A. Franceschini, B. Ginetti, M. Glavendekic, J. Hantula, G. Hartmann, M. Herrero, D. Ivic, M. Horta Jung, A. Lilja, N. Keca, V. Kramarets, A. Lyubenova, H. Machado, G. Magnano di San Lio, P.J. Mansilla Vazquez, B. Marais, I. Matsiakh, I. Milenkovic, S. Moricca, Z.A. Nagy, J. Nechwatal, C. Olsson, T. Oszako, A. Pane, E.J. Paplomatas, C. Pintos Varela, S. Prospero, C. Rial Martinez, D. Rigling, C. Robin, A. Rytkonen, M.E. Sanchez, B. Scanu, A. Schlenzig, J. Schumacher, S. Slavov, A. Solla, E. Sousa, J. Stenlid, V. Talgø, Z. Tomic, P. Tsopelas, A. Vannini, A.M. Vettraino, M. Wenneker, S. Woodward and A. Perez-Sierra. 2015. Widespread Phytophthora infestations in European nurseries put forest, semi-natural and horticultural ecosystems at high risk of Phytophthora disease. Forest Pathology.


Klapwijk, M.J., A.J.M. Hopkins, L. Eriksson, M. Pettersson, M. Schroeder, A. Lindelo¨w, J. Ro¨nnberg, E.C.H. Keskitalo, M. Kenis. 2016. Reducing the risk of invasive forest pests and pathogens: Combining legislation, targeted management and public awareness. Ambio 2016, 45(Suppl. 2):S223–S234  DOI 10.1007/s13280-015-0748-3  [ ]


Liebhold, A.M., T. Yamanaka, A. Roques, S. Augustin, S.L. Chown, E.G. Brockerhoff, P. Pysek. 2016. Global compositional variation among native and nonindigenous regional insect assemblages emphasizes the importance of pathways. Biological Invasions (2016) 18:893–905


Seebens, H. et al., 2017. No saturation in the accumulation of alien species worldwide. Nature Communications. January 2017. [ ]



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.


Posted by Faith Campbell



Bill aimed at controlling invasive species on the ground advances

whitebark pine in Crater Lake National Park killed by white pine blister rust; photo by F.T. Campbell

In the first days of April, the Senate Environment and Public Works Committee  adopted the Wildlife Innovation and Longevity Driver Act (S. 826) (the WILD Act).

Title II of this legislation would amend the Fish and Wildlife Coordination Act by inserting language very similar to the Federal Land Invasive Species Control, Prevention, and Management Act (S. 509).  I blogged last year about that  bill and a hearing about it here.

Our concerns at the time focused on:

  • The provision allowing invasive control projects to proceed without first being evaluated by an environmental impact statement or environmental assessment. Lack of careful analysis could expose the environment to additional damage. For example, use of herbicides or grazing to control invasive plants can lead to suppression of native forbs. Suppressing invasion by one set of plants – whatever the strategy used – often facilitates a secondary invasion.
  • The mandatory funding allocations – which severely limit funds available to support research, outreach, and strategic planning and coordination – could undercut activities crucial to development and implementation of effective strategies and management tools.
  • The mandatory goal of reducing invasive species populations by 5% per year is unrealistic.
  • New requirements on reporting and coordination might divert already-thin resources and delay needed action.
  • Priority-setting. Managing invasive species on national lands should reflect national goals and perspectives, not be set by states’ governors.

Caroline Murphy of The Wildlife Society and I have reviewed Title II of the new WILD Act and find that it differs from last year’s invasive species control bill in several important ways:

  • The bill now applies to a wider range of agencies. The Secretary of the Army (who supervises the Corps of Engineers) is included explicitly; he joins the secretaries of Interior and Agriculture (as supervisor of the Forest Service). In addition, the bill also applies to the head of “any federal agency” having duties related to planning or treatment of invasive species “for the purpose of protecting water and wildlife on land and in water.”
  • Most important, projects are no longer granted a “Categorical Exclusion” from preparing environmental impact analyses. Instead, under an “Expedited Action” provision, the Secretaries are instructed to use all existing legal tools and flexibilities to expedite projects and activities.
  • The bill still requires that 75% of invasive species funds be allocated to “on-the-ground control and management of invasive species.” But such activity now may include “the use of appropriate methods to remove invasive species from a vehicle or vessel capable of conveyance.” I wish the language also included efforts to prevent invasive species from being present in or on the vehicle or vessel.
  • The bill has dropped the requirement that invasive species’ populations be reduced by 5% annually. The bill now requires the Secretaries to develop a strategic plan “to achieve, to the maximum extent practicable, a substantive annual net reduction of invasive species populations or infested acreage on land or water” that the Secretary manages. It is still not clear whether that reduction should apply to some or all of the invasive species there.

I am still concerned that

  • Projects are to use least-cost methods. This requirement is likely to favor reliance on chemical controls, which could have significant non-target impacts and might not provide lasting control. This incentive might be counter-balanced by the requirement that the methods be effective, based on sound scientific data. However, the bill’s focus on measuring annual results rather than long-term efficacy will add to pressures to rely on short-term approaches that could undermine long-term effectiveness.
  • Leadership of the projects – especially setting priorities – will be in hands of state governments, not the federal agencies which have the responsibility under federal law to manage the lands and waters that are to be protected. A partial counter-balance is the requirement that the appropriate federal agency Secretary determine which lands or waters need immediate action to address the invasive species risk.  Furthermore, the expedited actions are to be carried out in accordance with agency procedures, including any applicable land or resource management plan

I welcome the requirement that the Secretaries, in developing their strategic plans, must take into consideration the ecological as well as the economic costs of acting or not acting.

As before, the projects are to be carried out through collaboration with wide range of partners, including private individuals and entities – apparently including non-governmental organizations such as state or local invasive plant coalitions.

The rest of the WILD Act would reauthorize the Partners for Fish and Wildlife Program, some Multinational Species Conservation Fund Programs, and create several conservation-related competitive grant programs to be managed by the National Fish and Wildlife Foundation, one of which is for the management of invasive species.

Now that these provisions are incorporated into a wider bill, and Senator Barasso is chairman of the full committee, adoption of some version of this legislation now seems more likely than I thought last year.  Apparently there is still no action in House on the parallel bill.

While I am heartened by some of the changes in the bill since last year, I continue to think that America’s public lands would be better protected by a more comprehensive approach that includes prevention, mapping, early detection, research, prioritization, coordination and outreach aimed at engaging key stakeholders.  Such an approach was outlined in a document developed a couple of years ago by the National Environmental Coalition on Invasive Species (NECIS) – available here.

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.

Alien species introductions — going up!

trade transports many invasive species

Containers at Long Beach, California; courtesy of the Port Authority

In an article published recently in Nature Communications , Hanno Seebens and 44 coauthors show that the rate of new introductions of alien species has risen rapidly since about 1800 – and shows no sign of slowing down. See a summary of the article with revealing graphs here .

Through analysis of a database covering 45,813 first records of 16,926 alien species established in 282 distinct geographic regions, the authors determined that the number of new species reports reached a maximum of 585 in 1996 (or an average of more than 1.5 sightings per day).

Of course, whether a species’ introduction is detected depends on a variety of factors. One of the most important is the species’ impact – or lack thereof! – on economically important resources – this determines whether the species gets noticed. Furthermore, detection usually happens some time after a species’ actual introduction. And, regardless of factors motivating human attention, some types of species are more easily detected than others. All these factors skew the findings. Because many introductions are not detected, Seebens et al. note, their data underestimate actual introductions.

The authors found that the adoption of national and international biosecurity measures during the 20th century have slowed introductions – but they are not yet sufficiently effective. Most notably, numbers of reported new introductions of fish and mammals have decreased since the early 1950s. Of course, introductions of these taxa are usually the result of deliberate decisions, usually by authorities. It is encouraging that authorities appear to be getting the message that adding new species to an ecosystem is a risky enterprise.


Japanese honeysuckle; courtesy of

However, not all deliberate introductions have been curbed. Seebens et al. were surprised to see that vascular plant species introductions remained at such a high rate throughout the 20th century. Introductions of birds and reptiles also continue to rise, largely as pets in countries with strengthening economies.

For those plants and animals that are introduced primarily accidentally as stowaways on transport vectors or contaminants of commodities (e.g., algae, insects, crustaceans, molluscs and other invertebrates), Seebens et al. found a strong correlation between their spread and the market value of goods imported into the region of interest.

Having noted that almost all biosecurity efforts are not yet slowing introductions adequately, Seebens et al. point to New Zealand as the exception. That country adopted the Biosecurity Act in 1993 and the Hazardous Substances and New Organisms Act in 1996.

Although 20 years is a short period to gauge a policy’s efficacy – especially given time lags in detecting introductions – Seebens et al. say the stringent new policy appears to be succeeding. They found a significant decline in the number of new alien plants detected in New Zealand since the 1990s. New Zealand’s laws rely on a “white list” of permitted species rather than the more usual “black list” of prohibited species. New Zealand requires a risk assessment before a decision is made to allow any new species to be brought into the country.

Of course, such an approach does not apply easily to the taxa most often introduced as unintended hitchhikers on, or as contaminants of, imported goods, packaging, or transport vehicles – such as tree-killing insects and diseases. The paper notes that existing biosecurity regimes have not slowed down the accumulation of alien species introductions overall, but especially those arriving mainly accidentally, such as invertebrates and pathogens.

As a consequence, Seebens et al. expect that the numbers of new alien species will continue to increase.

I have previously blogged about other studies that show continuing introductions of forest pests and other specific taxonomic groups.  See blogs about (1) 2014 IUCN report on invasive species threats to World Heritage sites; (2) IUCN analysis of red-book-listed species – causes of endangerment; (3) rate of new plant pests being detected in US; (4) Jung et al. on Phytophthoras in Europe; (5) Zamir’s critique of international the phytosanitary system; (6) Klapwjik et al. on European efforts to strengthen regulations governing movement of living plants; (7) ISPM#15 11th anniversary.

Other recent studies have also examined the bioinvasion situation for the whole Earth or major regions. Liebhold et al. 2016 studied insect assemblages in 20 regions around the world. They found that which insect orders are present in a particular region differs completely depending on whether one is looking at native or at nonindigenous assemblages. The authors believe that difference is largely caused by the varying probability that an insect taxon can take advantage of one or more high-volume invasion pathways – such as trade in agricultural products, movement of plants by international travelers, shipments of stored grain, trade in living plants, hitchhiking (e.g. on the outside of shipping containers) and wood packaging. Pathway association appeared to be more important than insects’ life-history traits, which affect their ability to establish in a new ecosystem.

Maartje J. Klapwijk and several colleagues note that growing trade in living plants and wood products has brought a rise in non-native tree pests becoming established in Europe. The number of alien invertebrate species has increased two-fold since 1950; the number of fungal species has increased four-fold since 1900.

Jung et al. (2015) studied the presence of Phytophthora pathogens in nurseries in Europe. They found

  • Two-thirds of the Phytophthora taxa detected in European nurseries by the present study were unknown to science before 1990.
  • None of the 59 putatively exotic Phytophthora taxa detected in the present study had been intercepted at European ports of entry.
  • Spread of the quarantine organism ramorum has not been halted despite the presence of strict quarantine regulations.

I will post a blog examining introduction rates for tree-killing insects and pathogens specifically in the near future. In the meantime, see the published studies listed below as well as my earlier blogs and fact sheets posted here .

Aukema, J.E., B. Leung, K. Kovacs, C. Chivers, K. O. Britton, J. Englin, S.J. Frankel, R. G. Haight, T. P. Holmes, A. Liebhold, D.G. McCullough, B. Von Holle.. 2011. Economic Impacts of Non-Native Forest Insects in the Continental United States PLoS One September 2011 (Volume 6 Issue 9)

Aukema, J.E., D.G. McCullough, B. Von Holle, A.M. Liebhold, K. Britton, & S.J. Frankel. 2010. Historical Accumulation of Nonindigenous Forest Pests in the Continental United States. Bioscience. December 2010 / Vol. 60 No. 11

Haack RA, Britton KO, Brockerhoff EG, Cavey JF, Garrett LJ, et al. (2014) Effectiveness of the International Phytosanitary Standard ISPM No. 15 on Reducing Wood Borer Infestation Rates in Wood Packaging Material Entering the United States. PLoS ONE 9(5): e96611. doi:10.1371/journal.pone.0096611

Leung, B., M.R. Springborn, J.A. Turner, E.G. Brockerhoff. 2014. Pathway-level risk analysis: the net present value of an invasive species policy in the US. The Ecological Society of America. Frontiers of

Liebhold, A.M., T. Yamanaka, A. Roques, S. Augustin, S.L. Chown, E.G. Brockerhoff, P. Pysek. 2016.  Global compositional variation among native and nonindigenous regional insect assemblages emphasizes the importance of pathways. Biological Invasions (2016) 18:893–905

Lovett, G.M., M. Weiss, A.M. Liebhold, T.P. Holmes, B. Leung, K.F. Lambert, D.A. Orwig , F.T. Campbell, J. Rosenthal, D.G. McCullough, R. Wildova, M.P. Ayres, C.D. Canham, D.R. Foster, S.L. LaDeau, and T. Weldy. 2016. Nonnative forest insects and pathogens in the United States: Impacts and policy options. Ecological Applications, 0(0), 2016, pp. 1–19. DOI 10.1890/15-1176.1



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.


New Secretary of Interior Pledges to Support Invasive Species Efforts — Let’s Ask USDA Secretary to do the Same!

Interior Secretary nominee Ryan Zinke

During his confirmation hearing Ryan Zinke, nominated to be the new Secretary of Interior, committed to several senators that he would explore ways to better manage invasive species on federal lands – especially in National parks – and to strengthen the National Invasive Species Council (NISC).

Mr. Zinke is currently a Congressional Representative from Montana. Senator Debbie Stabenow (MI) pressed him on invasive species issues during the hearing, focusing on the threat to the Great Lakes of carp and other aquatic species. Also, Senators Al Franken (MN), Joe Manchin (WV), and Mazie K. Hirono (HI) asked about invasive species in written questions submitted to the nominee.

Mr. Zinke answered most questions the same way:  He shares the Senator’s concern, especially since  Montana has significant invasive species problems. Also, he thinks it is critical that federal land managers be encouraged and empowered to be good neighbors in controlling invasive species in cooperation with adjacent private land owners. …  Specifically he wants to explore ways to implement the Early Detection Rapid Response Framework adopted by NISC in 2016.


* Sen. Franken included a single question on bioinvaders among a long list of questions on other topics. He mentioned the emerald ash borer as one example of a damaging invader in Minnesota. Senator Franken asked Mr. Zinke:

1) what steps he would take to enhance invasive species control on public lands

See paragraph above for Mr. Zinke’s answer.

2) whether he would enforce the Lacey Act and explore ways to strengthen it.

Mr. Zinke said he would enforce the law. He is aware that there is broad bipartisan frustration with the lack of an efficient process for listing injurious species under the Act. He would ask the Fish and Wildlife Service to recommend ways to improve its implementation. If legislative changes might be helpful, he would be pleased to have that conversation with the Congress.


* Sen. Manchin’s first question (!) asked how Mr. Zinke might strengthen NISC to help manage invaders across multiple types of land ownership. See Mr. Zinke’s frequent reference to his Montana experience above for his answer.


* Sen. Hirono asked five questions pertaining to invasive species! Her first question concerned steps to protect National parks (especially in Hawaii) from bioinvasion. Here, Mr. Zinke gave his usual response but added: “I am especially concerned that Hawaii’s unique flora and fauna are vulnerable to invasive species. I would not want to see invasive species push any of these unique plants and animals onto the Endangered Species list. Once confirmed, I will ask the National Park Service to present me with options for better protecting our national parks from invasive species.”


Ms. Hirono also asked about strengthening NISC. Mr. Zinke responded as follows: “…, I will explore ways to improve the operations of the National Invasive Species Council, and actively engage with the Secretaries of Commerce and Agriculture to get off to a strong start on this issue. … We also need to create a more effective linkage between the National Invasive Species Council policy operation in Washington, DC, and the on the ground federal land managers across the country who deal with invasive species on a daily basis…”


Also, Sen. Hirono asked for Mr. Zinke to help Hawai`i and other U.S. Pacific islands to counter the spread of invasive species through movement of military equipment. Mr. Zinke said he would work to enhance coordination with the Department of Defense and the Pacific island communities to reduce the risks posed by invasive species. … explore how we may implement the recent framework for early detection and rapid response …


Mr. Zinke also promised to work with Senator Hirono on several issues under Interior jurisdiction that are priorities for Hawai`i, among them invasive species.



What We Should Ask the new President & Congress to Do re: Invasive Species

While there are many opportunities for the Congress to strengthen U.S. invasive species programs (see my blog from December 31 here, the most important activity NOW is the confirmation of Sonny Perdue as Secretary of Agriculture. Contact your Senators and urge them to ask Governor Perdue how he will address invasive species challenges.

USDA Secretary nominee Sonny Perdue

Possible questions:

Q: How serious do you think is the threat to American natural resources from invasive (non-native) insects, pathogens, and plants? Can you suggest steps you would take to strengthen the efforts of the Animal and Plant Health Inspection Service (APHIS) aimed at controlling introduction and spread of such bioinvaders into the United States?

Q: The principal legal authority for preventing introductions of invasive plants and plant pests is the Plant Protection Act. The PPA provides strong authority but its implementation has been hampered by internal USDA decisions. How would you ensure that the Department corrects these problems and actively enforces its regulations aimed at ensuring the health and productivity of America’s plant resources?

  • In recent years, more than 20 previously undetected plant pests have been detected in the country each year. Hundreds of shipments of goods entering the country each year contain plant pests. What strategies would you promote to reduce the introduction, spread, and impacts of invasive species?

Q: Given the ever-tightening budget allocated to agencies responsible for addressing invasive species threats, what steps would you take to ensure that our country does not suffer waves of new invasions?

If you have a working relationship with your Senators and believe they understand the invasive species issue fairly well, you might want to suggest more detailed questions:

Q: As you know, the Animal and Plant Health Inspection Service (APHIS) is responsible for preventing introduction and spread of plant pests.

  • In some cases, APHIS has been hesitant to use its authority to penalize importers which routinely receive shipments that violate plant pest (phytosanitary) regulations. [You might cite my blog from last week  which illustrates examples pertaining to wood packaging.] Will you instruct APHIS to use its legal authority to impose civil penalties to deter continuing violations?


  • Trying to prevent pest introductions by increasing the percentage of shipments that are inspected visually will not be effective in many cases. This is true especially with regard to one of the most important pathways by which plant pests are introduced – imports of living plant material such as nursery stock. APHIS began updating its regulations governing plant imports nearly four years ago, but the proposed new regulations have been not been finalized. Will you look into the reasons for delay and take steps to update these regulations to focus on pathway cleanliness rather than continue to rely on ineffective visual inspections?

Q: Urban forests across the country are under threat from a growing number of non-native or introduced insect pests. Examples include the emerald ash borer – now found in 27 states; Asian longhorned beetle – which threatens a large proportion of urban trees across the country; and polyphagous and Kuroshio shot hole borers – killing many trees in southern California.

Urban forests are at particularly high risk of infestation by non-native pests because they are growing near ports and other transportation hubs where such pests are first introduced. Furthermore, each individual tree in an urban setting provides important benefits in the form of shade, moderation of storm water runoff, abatement of air pollutants, enhanced property values, and neighborhood amenities.

  • Will you fully utilize the authorities under the Plant Protection Act to help ensure the health and productivity of America’s urban forests?
  • [If you have not already suggested the questions outlined above re: wood packaging and other pathways, you might suggest them in this context.]


The Secretary of Agriculture also oversees the Forest Service. Pertinent questions:

Q: Invasives are as great a threat to eastern forests as wildfires are in the West. Despite the growing damage and ecological destruction we are witnessing the budgets for research on strategies to minimize these bioinvaders’ impacts are actually falling. How will you work to provide solutions to this quandary?

As I said in my blog at the end of December, what is missing is a political demand for action – and support for necessary staff and funding. Agencies under the secretaries of Agriculture and Interior bear most of the responsibility for managing invasive species. As long as these officials are not being pressed by key Congressional committees, the media, and key stakeholders to take more aggressive and effective action to curtail species introductions and suppress established populations of bioinvaders, they will continue to focus their attention on issues that do generate these kinds of political pressure.

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.


What the new President & Congress Can Do re: Invasive Species

 White House


A new President and Congress take office in January.  And outgoing President Obama recently amended the Executive Order on invasive species.

What might the new leaders do to improve America’s invasive species programs?

Here are a group of actions that I think would improve programs significantly:

  • amend the Lacey Act to strengthen controls over introduction and spread of invasive animals and animal diseases;
  • raise the political profile of invasive species issues by holding more frequent oversight hearings;
  • increase funding for invasive species prevention, containment, and control programs;
  • support proposals to amend the 2019 Farm Bill to strengthen on-the-ground programs, policies, and research aimed at minimizing invasive species introduction, spread, and damage;
  • during the confirmation process, Senators should ask President Trump’s nominees to leadership positions in the Departments of Agriculture and Interior about how they will address invasive species challenges.

Do we need new legislation mandating that federal land-managing agencies do X or Y with regard to invasive species? This was the focus of a hearing in May at which I testified.

Federal land-managing agencies are already authorized and – in some cases required – to act to control invasive species on lands and waters under their jurisdiction.  Some of the existing statutes even authorize the agencies to apply fees paid by people who use the public lands for some purpose (e.g., livestock grazing, recreation) to management of invasive species.

Most of the statutes authorizing invasive species management incorporate that activity into the agency’s broader management goals for protection of wildlife, habitat, natural resources, historic or cultural sites, etc.  For example, the USFS Manual §2900 lists 21 laws and 6 regulations or policies that govern the USFS’ management of invasive species.  Some of these laws apply to all federal land-managing agencies, including:

  • Endangered Species Act (ESA) of 1973 (16 U.S.C. §§1531 et seq.)
  • Surface Mining Control and Reclamation Act of 1977 (30 U.S.C. 1201, 1201 (note), 1236, 1272, 1305). §515
  • North American Wetland Conservation Act 1989 (16 U.S.C. 4401 (note), 4401-4413, 16 U.S.C. 669b (note)). §9 [U.S.C. 4408]
  • Sikes Act (Fish and Wildlife Conservation) of September 15, 1960 (16 U.S.C. 670g-670l, 670o, P.L. 86-797), as amended. §201
  • National Historic Preservation Act of 1966 [16 U.S.C. §§470 et seq.]
  • Wilderness Act of 1964 (16 U.S.C. §§1131 et seq.

Other statutes apply only to resource management authorities of the USDA Forest Service; these include:

  • Organic Administration Act of 1897 (16 U.S.C. §§ 473 et seq.).
  • Fish and Wildlife Coordination Act (16 U.S.C. § 661 et seq.).
  • Knutson-Vandenberg Act of June 9, 1930 (16 U.S.C. 576, 576a-576b). §3 [16 U.S.C. 576b]
  • Bankhead-Jones Farm Tenant Act of 1937 (7 U.S.C. §§1010 et seq.)
  • Anderson-Mansfield Reforestation and Revegetation Act of October 11, 1949 (16 U.S.C. 581j (note), 581j, 581k)
  • Multiple-Use Sustained-Yield Act of 1960 (16 U.S.C. §§528 et seq.)
  • Forest and Rangeland Renewable Resources Planning Act (RPA) of 1974 as amended by the National Forest Management Act (NFMA) of 1976. §6
  • International Forestry Cooperation Act of 1990 (16 U.S.C. § 4501)
  • Healthy Forests Restoration Act of 2003 (H.R. 1904), [16 U.S.C. 6501-6502, 6511-18, 6541-42, 6571-78]
  • Wyden Amendment (P.L. 109-54, Section 434).
For brief descriptions of all these statutes, see the references and links at the end of this blog posting.

Advocates have tried before to legislate a specific requirement that federal agencies combat invasive species.  The Federal Noxious Weed Act of 1974 (7 U.S.C. § 2801 note; 7 U.S.C. § 2814) was amended in 1990 to add §15, “Management of Undesirable Plants on Federal Lands”.  This section requires each federal agency to

1) designate an office or person adequately trained to develop and coordinate an undesirable plants management program for control of undesirable plants on federal lands under the agency’s jurisdiction, and

2) establish and adequately fund an undesirable plants management program through the agency’s budgetary process,

3) complete and implement cooperative agreements with state agencies regarding the management of undesirable plant species on federal lands, and

4) establish integrated management systems to control or contain undesirable plant species targeted under cooperative agreements.

This approach hasn’t worked – no one is satisfied by the federal agencies’ “weed” management efforts.



What is missing is a political demand for action – and support for necessary staff and funding. Agencies under the secretaries of Agriculture and Interior bear most of the responsibility for managing invasive species.  As long as these officials are not being pressed by key Congressional committees, the media, and key stakeholders to take more aggressive and effective action to curtail species introductions and suppress established populations of bioinvaders, they will continue to focus their attention on issues that do generate these kinds of political pressure.

I am not saying that the principal statutes governing invasive species management could not be improved.  As noted above, several proposals have been put forward to strengthen laws which are the foundation for preventing introduction of invasive species.  I will blog about specific proposals in the new year.



USFS Invasive Species Manual

ANSTF/NISC report “Federal Policy Options Addressing the Movement of Aquatic Invasive Species Onto and Off of Federal Lands and Waters. 2015.  Committee on the Movement of Aquatic Invasive Species both onto and off of Federal Lands and Waters.

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.

A Red List for Trees!

16 dead sweet bay + grpF.T. Campbell  dead sweetbay, Florida Everglades

At the global level, the World Conservation Union (IUCN) is the recognized leader in conservation.  Information from the IUCN’s Red List has been widely used to inform conservation policies and legislation, as a tool for environmental monitoring and reporting, and to prioritize areas for conservation action.


The IUCN is holding its World Conservation Congress in Honolulu during the first half of September.  The several sessions focused on both invasive species and forests have been grouped into “Journeys”.  The invasive species Journey schedule is available here.  The schedule for the forest Journey is available here   I don’t think either puts much emphasis on the year-old Tree Specialist Group.


Over the decades, the Union has increasingly engaged on plant conservation issues. The plants under consideration now include trees! There are multiple ways that you can be part of this important effort. Details are below. One of the efforts’ leaders assures me that the IUCN process will address tree species not yet “endangered” but under severe pressure – currently or virtually certainly in the near future – from established non-native insects and pathogens.


The IUCN has noted that trees have high ecological, economic, and cultural value. Forests are being converted or degraded by many human-related activities, including overharvesting, fire and grazing – to say nothing of climate change and non-native pests. Yet – the impacts of forest conversion and degradation on tree species per se are largely unknown. How many tree species qualify for a “Red List” category: extinct, critically endangered, endangered, or vulnerable? (For a discussion of the criteria applied in assigning categories, go here.

(Of course, full-scale extinction or endangerment of a species is the extreme; ecological damage begins earlier and more locally, as the species declines as the result of a suite of pressures …)


The IUCN has formed a Global Tree Specialist Group to conduct a comprehensive conservation assessment of the world’s tree species, linked to IUCN’s Red List. The effort is being led by the Tree Specialist Group  and the Botanic Gardens Conservation International (BGCI). The group’s mission, underlying considerations and process are described in an article published in the Oryx article cited below.


IUCN has recently completed analyses of extinction risk in selected animal groups. They concluded that 14% of bird, 33% of amphibian, and 22% of mammal species are either threatened or extinct.


Preparing the same type of analysis for tree species will be more complicated. First there are many more plant species than ones in the selected groups of animals. Scientists don’t know the total number of extant tree species. One estimate is 60,000.  If that estimate is in the ballpark, the status of approximately 84% of tree species has not yet been assessed. Assessments of tree species begun in the 1990s have resulted in approximately 9,500 species being included in one of the Red List categories.  They represent slightly less than half of all plant species listed.


To achieve the goal of assessing the status of all tree species by 2020, organizers plan to adopt the approach used successfully in the recent assessments of vertebrate groups – mobilizing global data sets (which have become more numerous and easier to use) and hundreds of volunteer experts.


To start, the Group is focused on specific plant families with high numbers of trees, e.g., Aquifoliaceae, Fabaceae, Fagaceae, Lauraceae, Meliaceae and Myrtaceae. Combined, these families include more than 20,000 species. Assessments of Betulaceae and Ebenaceae have already started, led by BGCI and the Missouri Botanical Garden, respectively.


Project leaders hope to complete 5,000 more tree assessments – new or updates – during 2016.


What is Under Way


Other IUCN specialist groups are assisting in assessing the status of trees in various geographic regions or with particular human uses. The IUCN Plants for People initiative is already assessing timber, medicinal and crop wild relatives. The Crop Wild Relative Specialist Group has prepared draft assessments for over 90 woody species of Malus, Prunus, Pistacia and Mangifera. Specialist Groups and Red List authorities in South Africa, Brazil, and East Africa and several island groups are contributing.


A third focus will be tree species presumed to be most at risk from climate change, e.g., montane and island trees. IUCN Specialist Groups in Hawai`i, New Caledonia, Galapagos, Mascarene Islands, Fiji, and Madagascar are working.


The BGCI is making progress on assessing Europe’s non-coniferous trees. If you wish to help, contact Malin Rivers at


In North America, the U.S. Forest Service hosted a meeting on “Gene Conservation of Tree Species” at the Morton Arboretum in Chicago in May 2016. Murphy Westwood facilitated a special session during which “listing” experts from IUCN, NatureServe, USFS CAPTURE Program, and the U.S. Fish and Wildlife Service compared their assessment processes and discussed how data might be shared more efficiently. A goal of completing the IUCN Red List of North American Trees was agreed on. The Morton Arboretum will help coordinate the effort. To contribute please contact Murphy Westwood at  


One suggestion was to conduct an IUCN Red List assessment for the genus Fraxinus. Two ash species – one Asian, one Central American – are included in the IUCN Red List (although one needs to be updated). Jeanne Romero-Severson of Notre Dame University has offered to undertake assessments for green ash, Fraxinus pennsylvanica, and black ash, Fraxinus nigra. If you wish to help, contact Sara Oldfield at


(I think several other species also warrant IUCN assessment, including redbay Persea borbonia, tanoak Notholithocarpus densiflorus, and whitebark pine Pinus albicaulis)


This IUCN effort represents yet a fourth set of people examining tree-pest interactions – people integrated into traditional, internationally-focused conservation organizations. There are at least three other groups already involved: (1) forest pest experts in academia and government agencies, (2) people who focus on invasive species, and (3) phytosanitary officials. I think that these latter three groups already interact less smoothly than would be ideal. How can we all combine our efforts to enhance protection programs?


Might more of the scientists who work on insects and pathogens attacking tree species join the IUCN Tree Specialist group? Might organizers of meetings make a greater effort to engage people from all four silos in discussions of strategies? Might some virtual for a be established that could facilitate communication across the gaps – perhaps emphasizing the gap between invasive species experts and phytosanitary officials?


Finally, how can we use the new focus on tree species’ degree of endangerment to enhance efforts to prevent and respond to invasions by non-native insects and pathogens? How do we link these concerns to existing attention to the ecological and economic impacts – which begin to manifest long before a species qualifies as “endangered”.  How can the various approaches reinforce each other?





Newton, A., S. Oldfield, M. Rivers, J. Mark, G. Schatz, N. Tejedor Garavito, E. Cantarello, D. Golicher, L. Cayuela, and L. Miles. 2015. Towards a Global Tree Assessment. Oryx, Volume 49, Issue 3, July 2015, pp. 410-415.


Explanatory information available at


The GTSG Newsletter is apparently available only to those who are part of the IUCN network.


For more information, contact Sara Oldfield, Co-Chair GTSG, at




Posted by Faith Campbell

What Happens When Decision-Makers (= politicians) Don’t Hear from Us

Decisions and delays that undermine vital phytosanitary programs …


champion green ashchampion dead

Michigan’s champion green ash – before and after emerald ash borer entered the state


Sometimes, when a shipment arriving at a U.S. port is found to be enclosed in wood packaging that is infested by pests, the importers complain to top-level officials. Sometimes, those officials respond to the pressure by allowing that shipment to enter the country – contrary to policy and common sense.

I learned recently of a particularly upsetting situation. A shipment of car parts arrived at a seaport. The wood packaging was found to be infested by a wood-boring insect that attacks pines and possibly other conifers. Because adults were present, the shipment could not be fumigated – because adult insects can escape during that process.

According to U.S. regulations, the shipment should have been refused entry to the U.S. and placed back on the ship to be transported elsewhere.

But what happened instead? The importer – a major auto manufacturer – complained to Michigan political leaders that delay in receiving the “just in time” shipment would result in halting production and unemployment.

Michigan governor Snyder and both Senator Debbie Stabenow and Senator Gary Peters put pressure on the U.S. Secretaries of Agriculture (who supervises APHIS) and Homeland Security (who supervises the Bureau of Customs and Border Protection). The two secretaries agreed to allow movement of the pest-infested shipment from the seaport across half the country to Michigan. They overruled their staffs and endangered our forests – most immediately along the shipment route. Those forests provide wildlife habitat, carbon sequestration, water supplies and other ecosystem serves; as well as numerous jobs and industries. It will be years before we know whether pests escaped the containers during transport and established in any of the wildland, rural, or urban forests along the route.

Had the shipment been refused entry — as the law requires — a new shipment in pest-free crates would have arrived within weeks.

It is particularly ironic that this pressure was exerted by Michigan officials. You would think that Michigan officials would remember the devastation to their state caused by the emerald ash borer and —  instead — press for vigorous enforcement of effective phytosanitary rules.

Of course, the Federal officials responsible for protecting our Nation from damaging plant pests should be strong in the face of political pressure. They should enforce regulations adopted through the appropriate regulatory processes. However, in this case, they chose the politically expedient action instead of carrying out their legal responsibilities.

A second example:

Since 2010, APHIS and its Canadian counterpart, Canadian Food Inspection Agency, have tried to amend the two countries’ regulations to require that wood packaging used to support or contain goods traded between the two countries conform to the international standard (ISPM#15). (When they initially adopted ISPM#15 in 2004, the U.S. and Canada exempted their bilateral trade.)

Why end this exemption? Both countries realize that each country harbors pests – native or introduced – that could pose a threat to forests in the other country. Also, the exemption complicates enforcement of the standard for shipments that originated elsewhere, e.g., in Europe or Asia.

For example, shipments of Italian decorative tiles that had been held in Canadian warehouses have been sent later to retailers in the U.S. Shippers have claimed that the pallets supporting the tiles are of Canadian origin, so they don’t need to have the stamp certifying treatment. Customs officials say that sometimes the evidence counters this claim – leading them to conclude that the pallet actually accompanied the load of tiles throughout its movement from Italy and thus is in violation of both U.S. and Canadian rules.  I expect that Canadians could cite examples of the same problem arising with shipments from U.S. warehouses to Canadian retailers.

Still, despite the need to end the exemption, APHIS’ proposed rule has been stuck at higher levels in the Department of Agriculture due to opposition by the Chamber of Commerce and some business associations.

Why are top-level politicians and other officials undermining phytosanitary programs? Do they not know the costs they’re risking?

I think it is at least partly because those of who know about the pest risk associated with wood packaging lack powerful and vocal allies who can educate the policy-makers about the damaged caused by introduced tree-killing pests.

For a reminder – woodborers have been estimated by Aukema et al. 2011 to cost local governments $1.7 billion per year; homeowners pay another $760 million to remove dead trees from their property. For more information, see also my blogs posted in July, August, September, and October 2016; fact sheets posted here and articles by Aukema et al. 2011 and Lovett et al. 2016. Remember that the costs discussed in these papers don’t reflect the vast majority of environmental and ecosystem losses, including disruption of such unique ecosystems as black ash swamps from New Brunswick to Minnesota and tree hammocks in the Everglades. Nor do they include the losses of cultural resources to Native Americans, such as basket weavers of the North and medicinal plants for Tribes in Florida …

You would think that federal and state officials who have lived through the disasters resulting from introduced wood-borers would want strict enforcement of customs and plant health regulations intended to prevent introduction of additional tree-killing pests. But these people respond to what they hear from the public and the media – perhaps the loudest voice they heard most recently. Unfortunately, people who care about invasive species – specifically tree-killing insects and pathogens – don’t have spokespeople.

Do you think the President or even Secretary of Agriculture is hearing about tree-killing pests every week? From whom? Not the Chief of the USDA Forest Service. Not the forest products industry. Not leaders of conservation organizations. Do governors, mayors, or heads of state agriculture or conservation agencies speak to Senators or Members of Congress — routinely and repeatedly — about the need to better protect our forests from non-native pests?

The evidence is that they do not. And what is the result?  These decision-makers respond to pressure from importers who want access to traded goods – and who are quite vocal about their complaints. Politics is how our country makes important decisions. And in politics, the squeaky wheel gets the grease.

When was the last time any of these officials – USDA Secretary Vilsack, DHS Secretary Jeh Johnson, Governor Rick Snyder, Senators Stabenow and Peters – heard from constituents or from leaders of the agencies under their jurisdiction about the importance of preventing introduction of new wood-boring insects?  When did a Michigan news media outlet last publish a report that discussed the pathways or vectors by which these insects enter the country and the importance of enforcing rules adopted to prevent additional introductions?

I recognize that it can be difficult for staff to get the attention of their supervisors on such issues. For example, I have been told by several people that California Governor Jerry Brown was surprised to learn that sudden oak death had killed millions of trees in his state. How did he “learn” this? From an article in the Washington Post that reported on a recent scientific study (Cuniffe et al. 2016).  Staff of CalFire were very frustrated that their efforts to educate the Governor had not resulted in his understanding the pathogen’s impact.

So – what can we do to re-balance the politics of phytosanitary policy – so that our political leaders understand why phytosanitary rules are adopted and support both adoption and enforcement of strong, effective measures?

We need to

  • Speak up at every opportunity about the damage to our trees caused by non-native insects and pathogens and describe the policies and programs that can reduce that damage and the risk of additional introductions.
    1. Tell this story to elected officials at all levels
    2. Write letters to the editors of media outlets
    3. Offer to show officials and reporters examples of the damage
  • Educate members of other stakeholder groups and ask them to integrate this message into their interactions with officials and the media.


  • Election seasons provide opportunities to raise issues.
  • People taking up positions in January (whether elected or appointed) will be more open to learning about “new” issues than have been people who have occupied an office for some time.

Finally – these messages need to be repeated periodically. Proctor and Gamble does not make its profits  by asking us to buy their toothpaste once a year. We cannot duplicate a major corporation’s advertising budget – but we can speak up!



Aukema, J.E., B. Leung, K. Kovacs, C. Chivers, K. O. Britton, J. Englin, S.J. Frankel, R. G. Haight, T. P. Holmes, A. Liebhold, D.G. McCullough, B. Von Holle.. 2011. Economic Impacts of Non-Native Forest Insects in the Continental United States PLoS One September 2011 (Volume 6 Issue 9)

Cunniffe, N.J., R.C. Cobb, R.K. Meentemeyer, D.M. Rizzo, and C.A. Gilligan. Modeling when, where, and how to manage a forest epidemic, motivated by SOD in California. PNAS, May 2016 DOI: 10.1073/pnas.1602153113

Lovett,G.M.,  M. Weiss, A.M. Liebhold, T.P. Holmes, B. Leung, K.F. Lambert, D.A. Orwig, F.T. Campbell, J. Rosenthal, D.G. McCullough, R. Wildova, M.P. Ayres, C.D. Canham, D.R. Foster, S.L. LaDeau, and T. Weldy. 2016. Nonnative forest insects and pathogens in the United States: Impacts and policy options. Ecological Applications, 0(0), 2016, pp. 1–19. DOI 10.1890/15-1176.1


Posted by Faith Campbell


Why doesn’t state government take action to contain pests that threaten to cost 20 million Californians $1,800 apiece?

(The total cost will exceed $36 billion – which will be borne largely by homeowners and municipalities – meaning their taxpayers.  The state will bear little of this cost.)

PB036597 fate-sm smwillow tree in Tijuana River riparian area felled by KSHB.  Photo by John Boland; used by permission

(To see more scary photos of the damage along the Tijuana River taken by John Boland, go here.

The polyphagous (PSHB) and Kuroshio (KSHB) shot hole borers pose a great threat to many tree species in California – native species in natural and urban settings; non-native species used in plantings; and agricultural crops. Yet the state government is frozen in inaction.

These two shot hole borers attack hundreds of tree species; at least 40 are reproductive hosts. For details, view the write-up here or visit the UC Riverside website here.

Some of the important reproductive hosts for PSHB are listed here; those that are also known to support reproduction of the Kuroshio shot hole borer are marked by an asterisk.

  • Box elder (Acer negundo)
  • Big leaf maple (Acer macrophyllum) *
  • California sycamore (Platanus racemosa)
  • Several willows (Salix spp.)
  • Cottonwoods  (Populus fremontii & P. trichocarpa)
  • Several  oaks (Quercus agrifolia, Q. engelmannii, Q. lobata)

Several widespread exotic species also support PSHB reproduction: they include the invasive castor bean (Ricinus communis) and widely-planted London plane tree (Platanus x acerifolia).

US Forest Service scientist Greg McPherson has analyzed the vulnerability to PSHB of urban forests in cities in three regions of southern California: the Inland Empire, Coastal Southern California, and Southwest Desert. Together, these comprise 4,244 sq. miles and have 20.5 million residents. Dr. McPherson found that:

1) Approximately 26.8 million trees – 37.8% of the region’s 70.8 million trees – are at risk. Trees at risk include

  • 5 million coast live oaks,
  • 4 million ash,
  • 3 million sycamores and plane trees,
  • 9 million stone fruit or flowering Prunus species,
  • 5 million avocadoes, and
  • 8 million citrus trees.

2) The cost for removing and replacing the 26.8 million trees would be approximately $36.2 billion. This amount averages to $1,768 per capita.

3) The value of ecosystem services forgone each year due to the loss of these trees is $1.4 billion.

4) These estimates are conservative because they:

  • do not include costs associated with damage to people and property from tree failures, as well as increased risk of fire and other hazards
  • may undervalue benefits of trees to human health and well-being; and
  • do not include newly detected host species or the shot borers’ spread.

These disasters are highly likely to occur given the extent of current infestations and difficulty in curtailing spread of the beetle/fungus complex.


Natural areas – especially riparian areas – are also at risk.  John Boland reports that 70% of willows studied in the Tijuana River riparian area on the California/Mexico border were infested by KSHB.  Tree branches and boles weakened by beetle attack broke in the first winter storms in early 2016.  In some sections, “native riparian forest … went from a dense stand of tall willows to a jumble of broken limbs in just a few months.”  Trees growing in the wettest parts of the riparian area were most heavily attacked and damaged.  Three highly invasive plant species – castor bean, salt cedar, and giant reed – are barely or not attacked by KSHB.  The result of the damage to native willows and likely proliferation of the invasive plants is likely to be significant alteration of the entire biological system.

(While no one knows how KSHB reached the Tijuana River, John Boland says there is a greenwaste “recycling” center in the valley. See picture below, taken by John Boland.)


Regulatory action could help protect wildland, rural, and urban forests in the rest of the state – and possibly beyond. Scientists’ analysis of climate indicates that most of the urban and agricultural areas in California are at risk. The scientists have also begun analyzing the potential risk to other parts of country.


Why is the California government so unwilling to tackle a threat of this magnitude?

I have written about this inaction several times as it applies to the goldspotted oak borer. See my blogs on 1) California’s inaction on firewood in July 2015; 2) GSOB and firewood in September 2015;  3) contrasting states’ action on mussels with inaction on firewood posted in December 2015;  and 4) the threats to oaks, posted in April 2016.

In October CISP joined an eminent forest entomologist, Dr. David Wood of the Department of Natural Resources at the University of California, Berkeley.  We petitioned the California Department of Food and Agriculture to regulate movement of firewood within the state. CDFA refused, saying that the absence of control points through which firewood could be funneled made efforts to regulate its movements impractical. (For copies of our letter and CDFA’s reply, contact me through the “contact” button on the CISP website.)

While there are many questions about practical aspects of implementing and enforcing such regulations, I do not believe they are insurmountable.

I concede that CDFA has provided significant funds for firewood outreach campaigns. But people care about the threat posed by these pests and want CDFA to act. In the meantime, concerned people have formed formal partnerships linking local, county, state, and federal officials and academics to coordinate efforts to manage both GSOB and the PSHB and KSHB.  Groups’ efforts can be viewed here and here. CalFire and the California Fire Wood Task Force are active participants.

During a recent conference call sponsored by the California Agricultural Commissioners and Sealers Association’ Pest Prevention Committee, participants reinforced the damaging consequences of CDFA’s  inaction:

  • While scientists are developing new tools for detection of the polyphagous and Kuroshio beetles and the fungi, there are no funds to support their use in a more intensive detection trapping effort!!!!! Call participants discussed various potential funding sources (e.g., from competitive grant programs operated by various agencies).  Some survey efforts have been funded – by USDA APHIS:
    1. UC Riverside Professor Richard Stouthamer received Farm Bill §10007 funds for two years to develop traps and lures for PSHB.
    2. CDFA participates in a national woodborer survey which is funded by APHIS.
  • In the absence of CDFA designation of PSHB, KSHB, or GSOB as regulated pests, neither state nor county agencies have a firm foundation on which to base regulations to curtail movement of firewood, greenwaste, or other pathways by which these pests can be spread to new areas.

It is clear from the discussion during the call that many people understand the need for regulations to ban movement of firewood out of southern California. But so far they have not succeeded in building sufficient political support to bring this about.


Meanwhile, other federal agencies are beginning to perceive the risk posed by these pests – and are struggling to develop responses. The US Fish and Wildlife Service (USFWS) is trying to develop strategies to protect the forested wetlands, which are habitats for the endangered least Bell’s vireo (a bird) and other endangered species. However, the USFWS lacks funds to carry forward desired detection and other programs. The USFWS offices in California are trying to engage agency leadership on this threat. So far, Endangered Species Act §7 requirements have not restricted removal of infested trees in wetlands already invaded by PSHB or KSHB.


Santa Monica National Recreation Area is the first National Park Service unit to pay attention. I have written in the past that the National Park Service should adopt a nation-wide policy banning visitors from bringing their own firewood to campgrounds (see my blogs from August and October 2015). In the absence of a nation-wide policy, action by individual units is important.


The USDA Forest Service is already engaged, especially with detection and outreach. However, the USFS also does not have nation-wide policy restricting campers from taking their own firewood to campgrounds on National forests.


Many Californians are pushing for action … they need our help! If you live in California, contact your state legislators. If you live elsewhere, your forests are also at risk from the state’s failure to act.  So, if you know someone who lives there, ask that person to contact his/her legislators. Ask the legislators to demand state designation of PSHB, KSHB, and GSOB as quarantine pests and adoption of state firewood regulations.



Memorandum from Greg McPherson, USDA Forest Service, to John Kabashima Re: Potential Impact of PSHB and FD on Urban Trees in Southern California, April 26, 2016


Posted by Faith Campbell

Funding Levels Reveal Low Priority for Combatting Tree-Killing Pests

As the recent article demonstrated, non-native insects and pathogens pose a unique threat to America’s forests.  See also my blog posted May 10.

As Scott Schlarbaum and I said in Fading Forests III:

“Ultimately, then, the future of American forests is in the hands of our nation’s people.  In choosing our elected representatives, holding other government officials accountable, and making our private choices, we decide the priority of  whether addressing the causes and solutions to these pest issues is a priority – and, thus, whether we will keep of our natural heritage.  There is already a strong foundation for action.”

However, American society – as reflected in its political decisions – has not put a high priority on countering this threat. We outlined the long history of inadequate funding for USDA APHIS and USFS in chapters III and VI. Also, I wrote about the appropriations process for Fiscal Year 2017 (which begins in October) in my blog posted on March 22.


Recent action by the House of Representatives (see below) might signal a change. We shall have to wait to see whether this change lasts.


APHIS Funding

Too often, we think first of U.S. Forest Service funding as singularly important regarding non-native forest pests and pathogens. When it comes to prevention, though, its USDA’s Animal and Health Inspection Service (APHIS) that is key.

Total funding for the USDA APHIS in FY17 will be on the order of $939 million. The budget for its plant health program is about $310 million.  Included in this sum are mere tens of millions for addressing tree-killing pests:

  • Tree and wood pests — $54 million in the Senate bill, but only $45.9 million in the House bill
  • “specialty crops” — $167.5 million in the House bill, $158 million in the Senate bill; with only about $5 million likely to be spent on managing the sudden oak death pathogen, especially movement of infected plants, soil, etc. in the nursery trade.

The Center for Invasive Species Prevention and others had requested the higher number for “tree and wood pests”.  We think higher funding is appropriate given the number of highly damaging wood-boring insects already in the country – e.g., Asian longhorned beetle; emerald ash borer; redbay ambrosia beetle and its associated laurel wilt pathogen; the polyphagous and Kuroshio shot hole borers and their associated pathogens … (all these species are described here).  Furthermore, there is every likelihood that additional pests will be detected in the country since the wood packaging pathways remains leaky (see the Lovett et al. article cited above and my blogs about the wood packaging material pathway posted in July through October 2015).

The House bill specifies that $15 million of the “specialty crops” money should be allocated to citrus pests and pathogens, fruit flies, a grapevine pest and a multi-host pest (light brown apple moth).

USFS Forest Health Funding

Funding levels for the USDA Forest Service also demonstrate a low priority to countering non-native tree-killing insects and pathogens.

Total funding for the USFS is about $5 billion.  In making its request for $4.9 billion, the Administration allocated only $92 million to countering threats to forest health (on both federal and non-federal lands).

The House of Representatives’ Appropriations Committee has a different – and welcome – view: the House bill provides $114.6 million for forest health protection.  This is $15 million above the FY16 level and $22.55 million above the Administration’s request – a substantial increase unequaled in past years.  The accompanying committee report expresses concern about severe insect and disease threats, especially in California.  The report also notes that invasive forest pests threaten more than 58 million acres of the Nation’s forests.  The Committee encourages the Service to continue its work to assess future risks, control existing threats, research and develop new control methods, and improve the health of forest ecosystems.  Since only $5 million of the increase is to be used on non-federal lands, the “bump-up” for non-native pests will be modest.

A note of caution: the House expansion of funding for the forest health program was doubtless made easier by the House’s cuts to programs managed by the Environmental Protection Agency, which is funded by the same bill.)

The Senate bill follows the Administration in allocating only $92 million for forest health protection.

Not only has the Administration asked for less for the forest health program in recent years.  The funding allocations within that total trouble me.  In the current year (FY16), the USFS allocated only $20.2 million (15% of total forest health funds for this year) to specific projects targeting non-native insects or pathogens.  Nearly $10 million of these funds went to just one species – European gypsy moth.  The only other species receiving a significant proportion of the funds is hemlock woolly adelgid – HWA received $1.77 million. The second greatest allocation was to oak wilt — $466,000.  Ranking third is white pine blister rust, which was allocated $420,000.  A group of three species (goldspotted oak borer, thousand cankers disease, and laurel wilt) received a total $587,000.  This low figure does not, in my view, reflect the great damage caused by goldspotted oak borer and laurel wilt.  Furthermore, I assume that the polyphagous and Kuroshio shot hole borers are included in this grouping, although they are not listed specifically.  Both shot hole borers threaten many tree species in southern California riparian areas, and pose a possible threat to trees in other parts of the country.  All of these species are expected to receive less funding in FY17 under the Administration’s request.  (Again, all these species are described here).

(Native pests – southern and western bark beetles – received a total of $7.2 million in FY16. Invasive plants were allocated $1.7 million.  These figures are not included in my calculations in the preceding paragraph.)

USFS Research Funding

The House appropriations bill provides just under $292 million for research – the amount requested by the Administration.   The Senate bill cut funding for research to $280 million – a cut of $11 million from the FY16 level.  Worse, the Senate also added $2 million to the share of research funding allocated to foerst inventory.  The only mention of non-native pests and diseases in the report accompanying the Senate bill is a paragraph instructing the USFS to work with the USDI Fish and Wildlife Service, National Park Service, USDA APHIS, and state agencies to address the threat to the Hawaiian Islands’ `ohi`a trees from the Ceratocystis fungus (the disease is described here).  This report emphasizes the importance of continuing research on forest product utilization.

Even more troubling, for years the USFS has allocated only about 3% of its total research budget to research on “pest” species (including invasive plants).  Of this total, about half – $5 million – has been allocated to projects targeting non-native insects or pathogens.  This year (FY16), the highest funding went to hemlock woolly adelgid, at $1.782 million.  The second greatest amount was allocated to emerald ash borer —  $1.168 million.

(In FY16, the non-native western bark beetles received nearly $1.4 million in research funding; invasive plants received nearly $1.9 million.  Again, these figures are not included in my calculations above. )

USFS Wildfire Funding

One explanation for the Administration’s lower funding requests is the great pressure on the USFS to fund management of wildfire.  The agency now spends more than half of its annual budget to fight wildfires.  This situation is expected to get worse as the climate warms and fires become even more frequent and intense.

The Obama Administration’s budget proposals for both FY16 and FY17 asked Congress to set up a system to pay the costs of fighting extreme wildfires in the same way it finances the federal response to other natural disasters.  When hurricanes and tornadoes cause sufficient damage to be declared disasters by the president, the Federal Emergency Management Agency is authorized to exceed its annual budget and draw on a special disaster account. The account is adjusted each year to reflect the 10-year average cost of responding to such events.  President Obama suggested creating a similar exception for USDA Forest Service and Department of the Interior.

Currently, the USFS must obtain funds through annual Congressional appropriations – which are adopted too early for an accurate assessment of that season’s likely fire damage. When fire-fighting costs exceed the appropriation, the USFS must transfer money from other accounts – setting back forest restoration projects and efforts aimed at preventing wildfires.

The Obama administration asked Congress to end the need for such transfers by appropriating 70% of the 10-year average it costs to fight wildfires each year and allowing the Forest Service access to a disaster fund.

However, the Congress has been unwilling so far to establish the disaster fund.


The House bill’s welcome increase for the USFS forest health protection program – if enacted – would address pests that are already widespread.  Programs aimed at preventing introductions and responding to newly detected invasions – programs operated by APHIS – do not yet enjoy sufficient support from either the Administration or the Congress.

Advocates for stronger programs to combat non-native forest pests are exploring ways to ensure additional funding for key programs, especially early detection of and rapid response to newly detected outbreaks.  You will hear more about these ideas in future!


Descriptions of the Administration’s fire-funding proposal can be found at:


Posted by Faith Campbell


When will invasive species get the respect they deserve from conservationists?

i`iwi birdblogger i`iwi in Hawai`i

photo from; used with permission


Evidence is growing that invasive species are among THE major threats to conservation goals worldwide.

In 2015 the IUCN called invasive species the second most significant threat to those World Heritage sites around the world that have outstanding natural values. (Poaching is the greatest threat.) My October 21, 2015 blog showed that the IUCN report actually underestimated the impact of invasive species. I listed briefly the principal invaders in several U.S. National parks. Earlier blogs criticized the National Park Service for failing to regulate the movement of firewood (August 2015) and described the invasive threat to Hawai`i (earlier in October 2015).

Now a second study shows invasive species are a principal driver of species extinction. The authors assessed the prevalence of alien species as a driver of extinctions among plants, amphibians, reptiles, birds, and mammals (which are the best-studied taxa) post-1500 AD. Overall, 58% of extinct or extinct-in-the-wild species had been driven to extinction at least in part by invasive species. Invasive alien species are the second most common threat overall. Indeed, invasive species are the most common threat for vertebrate extinctions (62% of extinct or extinct-in-the-wild species faced threats from invasive species). Invasive species ranked fourth as a cause of extinction for plants: 27% of listed plant species were threatened by invasive species.

For those species with just a single driver of extinction, invasive species is the cause for 47% of mammals, 27% of birds, 25% of reptiles, and 17% of plants. In no case were invasive species identified as the sole threat to an amphibian species – although invasive species are their second highest threat.

Although the paper lists invasive species as second, their threat was virtually identical to that of “overexploitation”, the threat ranked first. That is, 124 out of 215 species studied were threatened at least in part by invasive species; 125 were threatened by overexploitation.

Other principal threats were overexploitation, agriculture, aquaculture, and – in the case of plants – residential and commercial development. Categories related to habitat loss ranked surprisingly low. Only 61 of the 215 cases listed agriculture and aquaculture as threats.

The authors reflect on whether invasive species are not themselves causal agents of extinction, but rather symptoms of the real causes, especially habitat destruction. They conclude that that is unlikely.

Instead, they suggest that invasive species impacts might often be underestimated, as many interactions – especially those between alien parasites and native hosts – are very hard to detect.

Not surprisingly, 86% of island endemic species had invasive species as one extinction driver. Nevertheless, continental organisms are also threatened — 14% of alien-related extinctions have been of species with mainland populations. These include eight amphibians, five birds, and six mammals. Most of these invader-threatened mainland organisms are from the Americas

Among the approximately 30 alien taxa named as extinction drivers are rats, cats, and trout as threats to other vertebrates such as birds and mammals. All three were also ranked highly as damaging invasives in the earlier IUCN report on World Heritage sites. Diseases – especially chytridiomycosis and avian malaria – were causal agents of extinction for amphibians and birds. Several herbivores – especially goats, sheep, and European rabbits – and alien plants were drivers of extinction for plant species.

Of course, outright extinction is not the only damage to biological diversity caused by invasive species. American chestnut, Fraser fir, and redbay are not extinct, but their ecological role has been virtually eliminated as the vast majority of these forest trees die off. Other tree taxa are on same road – ash and eastern hemlocks across wide expanses of their ranges; tanoaks; whitebark pines …

Invasive species pose major threats to biological diversity and other conservation goals. These damages are on top of the acknowledged threat of invasive species to agriculture, forestry, or economic groups. (See, for example, Lovett et al. 2016 discussed in my previous blog.) The role of invasive species in extinction described in this new paper suggest a long-standing bias among conservationists’ priorities. Too often, we have focused on species threatened by overexploitation – which is such easier to see and involves an obvious “villain”.

Nevertheless, a host of practical suggestions have been put forward to address the root causes of species introductions and spread. Often, these ask some or many of us to stop doing what we have been doing. But much meaningful conservation action requires someone to accept limits or to make sacrifices.

Will the conservation community – including grant-making foundations, federal and state agencies, and the many conservation non-governmental organizations ranging from the IUCN to local groups – now take up the challenge of implementing suggested actions and actively advocating for the funding needed for practical steps that will begin to bring this threat under control?



Bellard C, Cassey P, Blackburn TM. 2016 Alien species as a driver of recent extinctions. Biol. Lett. 12: 20150623. /


Lovett,G.M., M. Weiss, A.M. Liebhold, T.P. Holmes, B. Leung, K.F. Lambert, D.A. Orwig , F.T. Campbell , J. Rosenthal, D.G. McCullough, R. Wildova, M.P. Ayres, C.D. Canham, D.R. Foster, S.L. LaDeau, and T. Weldy. 2016. Nonnative forest insects and pathogens in the United States: Impacts and policy options. Ecological Applications, 0(0), 2016, pp. 1–19. DOI 10.1890/15-1176.1

Available at


Posted by Faith Campbell