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

i`iwi birdblogger i`iwi in Hawai`i

photo from www.TheBirdBlogger.com; 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. http://dx.doi.org/10.1098/rsbl.2015.0623 http://rsbl.royalsocietypublishing.org /


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 www.caryinstitute.org/tree-smart-trade


Posted by Faith Campbell

Experts describe forest pests’ impact, call for action


Sixteen scientists and policy analysts (including me) have published a new study reviewing recent work on numbers, pathways and impacts of non-native, tree-killing insects and pathogens. I encourage you to read the article. It provides a concise and compelling overview of the threat to our wildland, rural, and urban forests from non-native insects and diseases and proposes some thought-provoking solutions.

SOD Parke diseased plant

rhododendron infected by sudden oak death; photo by Jennifer Parke, Oregon State University

Meanwhile, here are our conclusions:

Current policies for preventing introductions have reduced the numbers of pests introduced via the various pathways (e.g., wood packaging and horticultural plants – but not sufficiently to counter pests’ rising opportunities for introduction resulting from burgeoning global trade. [Emphasis mine.]


At the current efficacy of implementing the international regulations governing wood packaging [ISPM #15] ( Haack et al., 2014),  and given growing trade, Leung et al. 2014 project that by 2050 – just 35 years from now – up to three times as many wood-boring insects may be introduced to the U.S. as are currently here.


(I discussed this high risk in blogs posted at this site on July 15 and August 22, 2015.)


The new paper presents several options for improving prevention. These include: measures to ensure exporters ship “clean” plants and wood packaging; post-entry quarantines to raise the likelihood that pests will be detected; placing all genera of North American woody plants on USDA’s NAPPRA list of genera not currently approved for import and awaiting risk assessment; and improved surveillance and eradication programs. We also note the importance of improving data collection and allowing  researchers outside USDA access to those data to support independent evaluation of policy’s effectiveness.


As Aukema et al. demonstrated six years ago, non-native forest insects have accumulated in U.S. forests at a steady rate of about 2.5 per year over the last 150 yrs. While the rate of introduction has not changed, the types of insects introduced have. In the 20th Century, plant-associated insects dominated the introductions. In recent years wood-boring insects associated with wood packaging materials have dominated. Some of these wood-borers also are highly damaging! (See emerald ash borer, redbay ambrosia beetle/laurel wilt, and polyphagous shot hole borer/Fusarium here). Lack of information precludes a similar analysis for pathogens; although we all know that the 20 or so high-profile pathogens cause great devastation – see descriptions here.


The whole country is at risk; although the highest numbers of tree-killing insects and pathogens are established in the Northeast and Midwest, Pacific Coast states are catching up (and certainly already have their share of devastating insects and pathogens).  See the map below.  You can check the pests in your state by visiting the interactive map here .


map developed by USFS; published in Aukema et. al 2010.

Our new article notes that these non-native pests are the only disturbance agent that has effectively eliminated entire tree species or genera from U.S. forests in the span of decades. Follow-on effects include alterations of ecosystem functions and huge costs to various stakeholders, especially residents and governments of (sub)urban areas.


These impacts can persist for centuries as a result of altered species composition, which affects multiple trophic levels.


We followed Aukema et al. 2011’s results in estimating the direct annual economic impact of non-native forest insects to be at least:  $2 billion in municipal government expenditures, $1.5 billion in lost residential property values, and $1 billion in homeowner expenditures for tree removal and replacement or treatment. These costs and losses contrast with the paltry $216 million estimated in federal government expenditures.


Aukema et al. 2011 noted that these expenses cannot be summed across cost categories because of the potential for double-counting. We note that these figures are probably underestimates for several reasons. They did not include the introduced diseases such as sudden oak death. Nor do they  include pests detected recently, such as the polyphagous shot hole borer.  Finally, our paper excluded consideration of insects or pathogens native to some part of North America, such as the goldspotted oak borer. (For more information about these organisms, consult the write-ups here.)


As our article notes, the billions of dollars in annual economic damages (and un-quantified ecological impacts) are economic externalities. That is, the importers who benefit from the economic activity do not pay directly for preventing or responding to the associated pest introductions.


The article discusses several policy options that we believe would greatly reduce unacceptable risks. These options include several bold actions:


  • Require importers to switch from packaging made from wooden boards to packaging made from materials other than solid wood (fiberboards ok). This change is both highly protective and potentially cost-effective. Such a switch would have to be justified under the terms of international trade agreements – but given the high levels of damage caused by wood-boring pests, I don’t think that hurdle is insurmountable.
  • Greatly strengthen measures aimed at preventing pest introduction on imports of plants. One step would be restricting imports of all genera of “woody” plants native to North America by designating them as “not authorized for importation pending pest risk assessment” (NAPPRA). Another protective step would be to promptly finalize the Q-37 revision proposed by USDA in April 2013 and immediately initiate negotiations with principal foreign suppliers of temperate climate woody vegetation to implement the pest-minimization procedures contained in that revised regulation, as well as in ISPM#36.


Other options discussed are straight-forward and simpler:


  • Tighten enforcement of existing regulations by ending the practice of allowing an importer to be detected five times in a year with wood packaging that does not comply with regulatory requirements before imposing a penalty. When a new year starts, that importer gets a “clean slate”! Is this how agencies enforce regulations that they are serious about?
  • Expand efforts to assist trade partners in adopting clean trade measures.
  • Expand and integrate surveillance programs for new pest outbreaks, and providing timely and adequate funding for emergency eradication efforts.




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, R. A., K. O. Britton, E. G. Brockerhoff, J. F. Cavey, L. J. Garrett, M. Kimberley, F. Lowenstein, A. Nuding, L. J. Olson, J. Turner, and K. N. Vasilaky. 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:e96611.


Leung, B., M. R. Springborn, J. A. Turner, and E. G. Brockerhoff. 2014. Pathway-level risk analysis: the net present value of an invasive species policy in the US. Frontiers in Ecology and the Environment 12:273-279.



Posted by Faith Campbell

Senate Hearing on Invasive Species Policy on Federal Lands

The Public Lands Subcommittee of the Senate Committee on Energy and Natural Resources held an oversight hearing on invasive species management on federal lands on April 28, 2016. This hearing is the result of lobbying effort by the Healthy Habitats Coalition, which drafted the initial bill and has worked for its passage for several years.  One specific aim was to gather comments on S. 2240.

yellow start thistle 1316001 Peggy Greb ARSyellow start thistle photo by Peggy Greb, USDA ARS  Bugwood # 1316001

The bill would, inter alia, require land-managing agencies to allocate their invasive species funds according to the following formula: 75% for on-the-ground activity; 15% for combined research and outreach; 10% or less for administrative costs. Priorities for federal agencies’ invasive species efforts would be set by state governors. The bill would also exempt some invasive species control programs from analysis under the National Environmental Policy Act (NEPA).

In December 2015 I posted a blog about an earlier hearing on the bill (H.R. 1485) held by the House Oversight Committee.


Witnesses represented the USDA Forest Service, USDI Bureau of Land Management, the Wyoming Department of Agriculture, Healthy Habitats Coalition, and I, representing the Center for Invasive Species Prevention and Natural Areas Association. The witnesses’ written testimony and hearing video are archived here

Senators at the hearing were Chairman Barasso (WY), Franken (MN), and Hirono (HI).  Senators Risch (ID), Hoeven (ND), and Gardner (CO) attended briefly.  About 13 Congressional staffers were there, along with an audience of 15-20 and two from the press.

In their introductions, all senators spoke about the economic damage caused by invasive species Chairman Barasso said his bill – S. 2240 — is intended to fix western complaints about the ineffectiveness of federal agencies’ efforts.  Senators Franken and Hirono agreed on the need for new tools and strategies and better coordination among actors. However, they expressed concern about some components of the bill.

At the end of the day …

The Healthy Habitats Coalition and the Wyoming Department of Agriculture support the bill. The USFS  supported the bill’s goals and emphasis on collaboration but had some concerns. BLM praised changes made from earlier versions of the bill, hopes additional clarifications will be made, and explicitly opposed the categorical exclusion from NEPA. CISP and NAA (I) opposed the bill and suggested that the Senators take other actions to strengthen federal invasive species programs.

Will the bill move forward? I think action is unlikely … It is a shame that Congress has so little concern about invasive species.  If there were a forward impetus, we could work with the Senators and Representatives to develop an approach that I think would be more productive.

Witness Statements

The administration witnesses took the usual approach, speaking about their agencies’ efforts and successes. Glenn Casamassa, USFS, noted the Service’s “leadership role” and spoke about programs across the agency. He estimated that the USFS treats ~400,000 acres per year for invasive species; the agency has restored about 2 million acres, with great success.

I question how these claims of success fit with the findings of USFS researcher Dean Pearson in Montana? I blogged about his studies in January. Pearson found that both invasion by alien forbs such as spotted knapweed and weed control efforts using either herbicides or grazing can lead to suppression of the native forbs. Furthermore, suppressing invasion by one set of plants – whatever the strategy used – often facilitates a secondary invasion by some other plant species that might cause greater changes to the system or that are harder to control. Such secondary invasions are likely any time a “strong” invaders relatively insensitive to the control method used is present.  Often this secondary invader is cheatgrass.

Mike Pool, BLM, noted that invasive plants occupy ~79 million acres of lands it manages and described particular successes in CO and NM. Key is a comprehensive and coordinated response.

Doug Miyamoto, Wyoming Department of Agriculture, said S. 2240 would rely on local leadership; ensure consistent commitment by federal partners; specify a goal of reducing invasive species’ acreage by  5% annually; and halt delays caused by NEPA compliance. As an example, he cited a four-year delay in managing a USFS site following fire, which resulted in doubling of cheatgrass extent.

George Beck, a weed scientist at Colorado State University, representing the Healthy Habitats Coalition, took Federal agencies to task for inconsistent budgets; lack of cooperation; lack of coordination with states; and using NEPA as an excuse for delays. Not expecting leadership from the federal government, he called on Congress to enact binding requirements through S. 2240.

Faith Campbell, representing CISP and the Natural Areas Association. I agreed that Federal leadership has fallen short and that the Nation needs a comprehensive invasive species program. I raised concerns about provisions of S. 2240:

  • Funding allocations would undercut essential research, outreach, and other activities aimed at development and implementation of effective tools;
  • These restrictions are exacerbated when combined with the unrealistic goal of bringing about 5% per year net reduction in invasive species populations;
  • New reporting and coordination requirements that might further delay needed actions;
  • Priorities in managing invasive species on national lands should reflect the national perspective, not be set by states’ governors.
  • The NEPA Categorical Exclusion could expose the environment to additional damage.

I called on the Senators to take several practical steps:

  1. Amend the Lacey Act to enable the Fish and Wildlife Service to
  • apply scientific risk assessment tools in evaluating species proposed for importation;
  • act quickly when confronted by an emergency.

Plus clarify FWS’ authority to regulate

  • all animal taxa (in coordination with USDA);
  • the threat to wildlife from disease; and
  • interstate movement of species already listed under the Lacey Act as “injurious”.
  1. Provide higher appropriations for key agencies: APHIS, FWS, EPA, Corps of Engineers, and the land and water-managing agencies.
  2. Conduct oversight hearings at which Senators ask Secretaries (of USDA & USDI) and their Assistant/Under secretaries about their efforts to address invasive species, specifically:
    • Has the USFS implemented its 2011 internal directive amending the Forest Service Manual? (The directive calls for integrating invasive species activities across programs on National forests and grasslands.)
    • Why has neither the USFS nor NPS adopted a nation-wide policy to limit campground visitors from bringing their own firewood?
    • Has/when will the Council on Environmental Quality collaborate with the National Invasive Species Council re to develop guidance on applying the National Environmental Policy Act (NEPA) to invasive species management?
  3. Ensure that when the Senate confirms nomimees to be new secretaries or assistant/under secretaries of USDI and USDA in 2017, those nominees are asked about their goals with regard to invasive species prevention and management.

Questions from the Senators

Much of the discussion centered around the bill’s language excluding invasive species control programs from NEPA. Chairman Barrasso, Miyamoto of Wyoming, and Beck all said NEPA compliance had caused damaging delays and described the Categorical Exclusion language in the bill as “limited”.

Pool said BLM has successfully used programmatic environmental impact statements to evaluate options over large areas ahead of time in order to act quickly in a crisis. Pool said that BLM distinguishes between catastrophic wildfire – when no NEPA analysis is required; When deciding how to respond to long-lived problems that affect hundreds of thousands of acres, BLM  wants to inform and engage the public – and NEPA  is a good process to do that.

Casamassa said USFS emergency responses on significant burned areas are not subject to NEPA; instead its actions are guided by Forest Plans.  He supported rulemaking to clarify the bill’s categorical exclusions for invasive species.

I opposed a NEPA Categorical Exclusion because all actions – even those based on good intentions – have downsides that need to be evaluated. (See discussion of Pearson’s research from my blog in December.) APHIS has used programmatic EIS to help agency move quickly. I expressed frustration that CEQ has stonewalled NISC on developing guidance.

(Whether the NEPA exemption is “limited” is open to discussion!  It would apply to projects on federal lands that are or will be “located in a prioritized, high-risk area” and treat invasive species within 1,000 feet of, inter alia, a water body or waterway; a railroad line or roadside; a water project; a utility or telephone infrastructure or right-of-way; a campground; a National Heritage Area or National Monument; a park or other recreational site; a school; or “any other similar, valuable infrastructure”.)

In response to Chariman Barasso’s question about the Early Detection/Rapid Response plan recently released by the National Invasive Species Council, Beck said that in his view states should take the lead in slowing the spread of species within the country.  He criticized federal agencies’ failure to halt new introductions.

Senator Franken expressed dismay that only one of the five witnesses’ written statements mentioned climate change as a factor re: invasive species. In response, the USFS and BLM stressed their efforts to adapt.

Senator Hirono asked whether the prescribed funding allocations in S. 2240 (75% for “on the ground” work; 15% for research and outreach combined; 10% for administration, including strategy and oversight) would hamper needed actions?  She cited the need for research to develop tools to manage the sudden `ohi`a death fungus [described as “ohia wilt” here.]  Casamassa of the USFS said the agency’s spending on invasive species is already close to the S. 2240 funding allocation.  Nevertheless, the agency would sometimes need greater flexibility. On the other hand, Beck said research on invasive species should be left to other agencies, such as the U.S. Geological Survey and Agriculture Research Service.

Senator Hirono expressed concern that the bill’s requirement that agencies use the “least costly” method would expand use of pesticides – an approach that concerns Hawaiians.

Senator Hirono asked Campbell whether the 5% reduction goal is do-able? Especially re: insects and pathogens? I replied that all agencies are dealing with hundreds of invasive species at a time. Many of the insects and pathogens – as well as the aquatics – can’t even be detected, much less the extent of invasion. Managers lack tools to reduce their extent.  I also worried that the 5% goal will put pressure on agencies to tackle easily measured invasive species e.g., plants, and ignore others.

Chairman Barrasso concluded the hearing by telling me that he thinks our views are not mutually exclusive. He sees the need for both prevention and control of widespread species.


Posted by Faith Campbell & Phyllis Windle