Wednesday, December 21, 2016

APHIS Adds Forty-four Counties in Georgia to the Emerald Ash Borer Regulated Area

Leah Bauer, USDA Forest Service Northern Research Station,

Effective immediately, the Animal and Plant Health Inspection Service (APHIS) is adding Banks, Bartow, Butts, Catoosa, Chattooga, Clarke, Columbia, Coweta, Dada, Dawson, Elbert, Floyd, Forsyth, Franklin, Gilmer, Gordon, Greene, Hall, Haralson, Hart, Heard, Jackson, Jasper, Lamar, Lincoln, Lumpkin, Madison, McDuffie, Morgan, Oconee, Oglethorpe, Paulding, Pickens, Polk, Rabun, Richmond, Spalding, Stephens, Taliaferro, Towns, Union, Walker, Warren, and Wilkes Counties in Georgia to the list of regulated areas for the emerald ash borer (EAB). APHIS is taking this action at the state’s request in response to the detection of EAB in Bartow, Gilmer, Rabun, and Union Counties

To prevent the spread of EAB to other states, the Federal Order outlines specific conditions for the interstate movement of EAB-regulated articles from the quarantined area in Georgia. Specifically, the interstate movement of EAB-host wood and wood products from the quarantined area in Georgia is regulated, including firewood of all hardwood species, nursery stock, green lumber, waste, compost, and chips of ash species.

EAB is an invasive wood-boring beetle that is native to China and other areas of East Asia. The beetle is present in some portions of the United States, and because of its continuing spread, APHIS has established regulated areas that are designated in the Code of Federal Regulations (CFR) at 7 CFR 301.53-3 and the Federal Orders located at:

The interstate movement of firewood from quarantined areas is an especially high-risk pathway for the spread of EAB. Therefore, APHIS works with state cooperators and foresters to prevent the human assisted movement of EAB, develop biological and other controls for EAB, and raise public awareness about this pest and the potential threats associated with the long-distance movement of firewood.

Wednesday, December 7, 2016

Spread by trade and climate, bugs butcher America's forests

Insect pests, some native and others from as far away as Asia, can undermine forest ecosystems. For example, scientists say, several species of hemlock and almost 20 species of ash could nearly go extinct in the coming decades. Such destruction would do away with a critical sponge to capture greenhouse gas emissions, shelter for birds and insects and food sources for bears and other animals. Dead forests also can increase the danger of catastrophic wildfires.
Today's connected world enables foreign invaders to cross oceans in packing materials or on garden plants, and then reach American forests. Once here, they have rapidly expanded their ranges.
There is more:  Please see the original article by Michael Casey and Patrick Whittle, Associated Press that is available at   

Monday, December 5, 2016

Executive Order -- Safeguarding the Nation from the Impacts of Invasive Species

Executive Order released on December 05, 2016
Safeguarding the Nation from the Impacts of Invasive Species

By the authority vested in me as President by the Constitution and to ensure the faithful execution of the laws of the United States of America, including the National Environmental Policy Act of 1969, as amended (42 U.S.C. 4321 et seq.), the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990, (16 U.S.C. 4701 et seq.), the Plant Protection Act (7 U.S.C. 7701 et seq.), the Lacey Act, as amended (18 U.S.C. 42, 16 U.S.C. 3371-3378 et seq.), the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.), the Noxious Weed Control and Eradication Act of 2004 (7 U.S.C. 7781 et seq.), and other pertinent statutes, to prevent the introduction of invasive species and provide for their control, and to minimize the economic, plant, animal, ecological, and human health impacts that invasive species cause, it is hereby ordered as follows:

Section 1. Policy. It is the policy of the United States to prevent the introduction, establishment, and spread of invasive species, as well as to eradicate and control populations of invasive species that are established. Invasive species pose threats to prosperity, security, and quality of life. They have negative impacts on the environment and natural resources, agriculture and food production systems, water resources, human, animal, and plant health, infrastructure, the economy, energy, cultural resources, and military readiness. Every year, invasive species cost the United States billions of dollars in economic losses and other damages.

Of substantial growing concern are invasive species that are or may be vectors, reservoirs, and causative agents of disease, which threaten human, animal, and plant health. The introduction, establishment, and spread of invasive species create the potential for serious public health impacts, especially when considered in the context of changing climate conditions. Climate change influences the establishment, spread, and impacts of invasive species.

Click here to read the entire Executive Order

Tuesday, October 18, 2016

Invasive Insects Cost the World How Much?!

An interesting article was recently published in Nature Communications looking at how much invasive insects cost worldwide.  Invasive insects are one of the more important categories of invasives, impacting shipping/trade, farming, ecology, forestry, health care, and more.

formosan subterranean termite (Coptotermes formosanus) damage.  Image credit: formosanus Scott Bauer, USDA Agricultural Research Service,

The article evaluated 737 existing studies, books, and reports from 1911 through December 2015 on the  economic cost of invasive insects cost. The articles/book/reports were first evaluated based on reproducibility of results and of the 737 initial sources, only 158 contained usable and relevant economic estimates.  Evaluation of those studies show that invasive insects, at a minimum, US$70 billion per year for goods and services and US$6.9 billion per year for human health.

The article was submitted with supplementary material which included a spreadsheet of the studies and numbers gleaned from each source.  For more information on the study and specific numbers for certain insects, check out the article.

Source Article: Massive yet grossly underestimated global costs of invasive insects
Science Direct Article: Invasive insects: Underestimated cost to the world economy

Wednesday, October 12, 2016

Thoughts from the International Congress of Entomology 2016

It has been a little over a week since we participated at the International Congress of Entomology 2016 in Orlando, FL and it was a great experience.  The Center for Invasive Species and Ecosystem Health hosted a booth in the Exhibit Hall for the week and we also participated in the Symposium: What Happens When Pest Occurrence Data is Shared: End of the World or New Horizons?

Image by: Rebekah D. Wallace
The conference had over 6,600 registered attendants and about half came from outside of the United States, representing 102 countries. It was a great opportunity to meet people we may not have another chance to otherwise.  In the six days that the Exhibit Hall was open and we were able to talk to over 260 people from at least 32 countries.  We talked at length with researchers from Nigeria, industry representatives from the U.K., academics from New Zealand, and more.  Some of the most interested attendees were the students who came from everywhere.  We were able to talk to people who had not heard of our program, those who only knew about one or two things that we do, and people who were avid supporters of Bugwood.

In working at the booth, we were able to make new connections with people who may be interested in using images from the Image Database in teaching and outreach.  Many were also interested in contributing images so that other researchers, teachers, students, etc. could have access to high-quality images.  We talked to people about EDDMapS and how we work with people in the invasive species community to map species occurrences across the U.S. and in Canada, and there were many people interested in potentially mapping in their own country, asking how we could work together to make that happen.  They learned about our smartphone apps and all of the types we have developed for reporting invasive species, identification, decision support, and more.  The teachers, and really anyone who has given a presentation, were interested in Bugwood Presents, our presentation database that allows you to upload, download, and embed presentations.

But, really, the greatest thing is when avid supporters would come to the booth and talk with other visitors about all of the things that we have done with them.  Countless projects, hours (and after-hours), travel time, webinars, e-mails, phone calls, and more with all of our partners is definitely worth it to hear how much people have been satisfied with the work we are doing.

Thank you to everyone who stopped by!

Monday, October 10, 2016

No-Till Agriculture Results in Greater Soil Microbe Biomass

Image by: Gerald Holmes, California Polytechnic State University at San Luis Obispo,

A recent study by University of Illinois College of Agricultural, Consumer and Environmental Sciences did a meta-data analysis of 62 studies across the world and found that there was greater soil microbe biomass in no-till agricultural systems as compared to conventional tillage agricultural systems.  Soil microbes are important because they breakdown plant biomass and release important nutrients back into the soil for absorption by other plants.  During 2010-11 in the U.S., about 23% land growing corn, cotton, soybeans, and wheat was on a farm where no-till/strip-till was used on every acre and about 56% had at least some of their land in no-till/strip-till.  Tillage practices can vary greatly by region and soil type.

Monday, June 27, 2016

Pollinators Threatened by Invasive Plants

"Invasive non-native plants have been found to reduce pollinator abundance and diversity, and disrupt pollinator services to some native plants, which could reduce seed production. Although our knowledge is still limited on the effects of invasive plants on pollinator abundance and diversity, and pollination of native plants, several studies have been conducted that answer some of those questions. Results of these studies will further our understanding of the influence of plant-pollinator interactions on native plant communities threatened by invasive plants." article by 
in TechLine, Invasive Plant News. The article contained summaries of several studies on this topic.

Click here to read the entire article.

Karan A. Rawlins, University of Georgia,

Thursday, May 26, 2016

Whole Foods is selling invasive lionfish in Florida

Whole Foods is now selling invasive lionfish at its Florida locations.

From USA Today: Since lionfish were first spotted in Florida in the mid-1980s, they have continued to spread rapidly. Florida’s Wildlife Commission estimates there are millions of the fish, which have no predators, and have wreaked havoc on native fish and shrimp populations.
Florida officials have pushed for people to combat the species in the kitchen by catching the fish and eating it.
Whole Foods is simplifying the process for Floridians who aren't into diving for their fish.
The chain began selling lionfish for $8.99 a pound on Wednesday and plan to raise the price to $9.99 a pound June 1.
To read the entire artical Click here.

Lionfish, Pterois volitans
by Rebekah D. Wallace, University of Georgia,

Monday, April 18, 2016

The usefulness, value and utility of BugwoodImages is demonstrated in the April 2016 Issue of “IPM Insights”, the Newsletter of the Northeastern (USA) IPM Center

Access the April 2016 Issue (Volume 13: issue 2) at:

An image of Colorado potato beetle taken by David Cappaert [Michigan State University] is used to illustrate the article “End of an Era of Easy Pest Solutions” about the issues of managing Colorado potato beetle.

An image depicting Palmer amaranth in a field taken by Howard Schwartz [Colorado State University] is used to illustrate the article “Eco Solutions Answer to Herbicide Resistance” about IPM solutions to managing herbicide resistance.

The article “Photographers Lift Pests’ Poise” is about images available for educational use that resulting from a Cornell University / Bugwood partnership that was established through a Northeastern IPM Center grant.  Additionally, an image depicting hesitant dagger moth larva by Bruce Watt [University of Maine] is used to illustrate this article.

An image showing fire blight symptoms by Rebecca Wallace [University of Georgia] is used in the article titled “Antibiotic-Resistant Fire Blight". 

Friday, April 8, 2016

Rampaging Radioactive Wild Boars Causing Havoc

by Lynne Hayes.  Original article in: Growing America. Friday April 8th, 2016

 Lynne Hayes’ article highlights a major invasive species problem being manifested in the Fukushima region of Japan, an area in Japan that includes the 12 mile radius of the “exclusion zone” that experienced the nuclear disaster resulting from the Fukushima Hamadōri earthquake and subsequent tsunami on 11 March 2011.  

As if a nuclear disaster wasn't overwhelming enough in the Fukushima region of Japan, now the farmers who live in the area are being overrun by wild boars—thousands of them—with razor sharp tusks. And to top it off, they’re radioactive.

They’re full of radiation, so not only can’t they be eaten, they must be buried in concrete pits much like any disposed of radioactive material.  That has created an even bigger problem in Japan—mass graves that were built to hold 600 boars each are already full and there is a shortage of people qualified to cremate them.

Their problem????  Not so fast: see the section: Pigging Out In America … feral hogs are OUR problem as well.  Though not radioactive, according to the USDA, the United States is home to more than 5 million feral hogs. These ‘cousins” of the wild boar are capable of devastating damage to crops and can seriously upset the balance of our ecosystem.

Friday, April 1, 2016

Map Callery Pear Challenge!

How many states are seeing Callery Pear becoming an invasive issue? Map infestations you see and let's find out! 
The University of Illinois is mapping Callery Pear in their state - Let's all join the challenge
The University of Illinois Extension Forestry is encouraging everyone in the state to map Callery Pear.  This invasive is rapidly spreading across the state.  Currently we have documented escaped populations in 65/102 counties in Illinois but we are sure it is more widespread than that.  And, based upon the data in, we are ahead of the other states in mapping this species!  As we are asking everyone in Illinois to help fill out our map, I want to challenge the other Midwestern states to do the same!  Let’s build a single map that relays the true distribution of this species across the Midwest!
 We’re asking everyone to report to or use the GLEDN app -
Christopher EvansForestry Extension and Research SpecialistUniversity of Illinois at Urbana-ChampaignDepartment of Natural Resources & Environmental Sciences
To find the best app in your area for mapping Callery Pear and other invasive species go to: EDDMapS Apps

Thursday, March 31, 2016

Trees in Trouble: A documentary film about America’s Urban Forests. Coming to PBS

Trees in Trouble: A documentary film about America’s Urban Forests. Coming to PBS broadcasting near you in association with Earth Day/ Arbor Day programming during the month of April. The film will be aired numerous times during the week of April 25th.
Trees in Trouble tells the story of Cincinnati’s response to the threat to its trees posed by the emerald ash borer. However, the film’s message is not limited to southern Ohio: across the country, from Massachusetts to San Diego, Minneapolis to Charleston, thousands of communities face the same threat: valuable and beloved trees being killed by non-native insects or diseases. While the trees and killers differ, the cost to the communities is the same: destruction of trees that provide shade and other important ecosystem services and create our sense of home. Trees in Trouble helps us understand what we are losing and links us to actions we can take to counter this tragedy.”   Faith Campbell, Vice President, Center for Invasive Species Prevention

 Check the PBS schedule chart at: to find out when Trees in Trouble will be airing on PBS in your area

Tuesday, March 29, 2016

Native Predators May Be Having a Larger Impact than Expected on Invasive Stink Bug

Entomology Today. March 25, 2016 issue. 
By Dr. Rob Morrison, USDA-ARS Appalachian Fruit Research Station in Kearneysville, WV. 

Research recently appearing in the journal Biological Control may change how we view native predators of the brown marmorated stink bug (BMSB). BMSB is an invasive species that was accidentally introduced to the United States from Asia in Pennsylvania, and has since been detected in more than 40 U.S. states. It feeds on more than 150 plant species, making it a large threat to many agricultural systems in the country.

Researchers with the USDA-ARS Appalachian Fruit Research Station and Shepherd University evaluated 25 native generalist natural enemy species collected from the field as potential predators of BMSB egg masses in the laboratory. 

To better evaluate and characterize damage inflicted by the various predators, the researchers photographed egg masses before and after predator exposure with the aim of linking egg damage to specific groups or guilds of predators.

Predators were also observed using videography, and some interesting behaviors emerged.  Bottom line, results suggest that native predators may not be getting as much credit as they deserve in the biological control of BMSB. 

Monday, March 14, 2016

USDA-APHIS Associate Administrator Shares some Trade Accomplishments

This USDA-Animal Plant Health Inspection Service (APHIS) Stakeholder Registry Release is worth a read. GKD 

March 14, 2016
Dear Stakeholders:

Now more than ever, producers need access to the global marketplace to expand their businesses and enhance their profitability. This is a message that is reinforced every time we meet with commodity representatives. These groups have come to rely on APHIS’ pivotal role in maintaining existing markets and negotiating new market opportunities based on sound science and meaningful protocols.

APHIS leads the way working with our programs to manage and resolve Sanitary and Phytosanitary (SPS) trade issues. In fiscal year (FY) 2015 alone, we facilitated and provided in-country support to successfully resolve 171 trade-related issues involving $2.5 billion in U.S. agricultural exports.

Our trade staff helped negotiate market access to China for all apple varieties from all U.S. states—a market worth an estimated $100 million. They also facilitated highly pathogenic avian influenza (HPAI)-related outreach and negotiations that helped the United States retain $248.9 million in poultry exports during the worst animal disease outbreak in U.S. history. At the same time, they were instrumental in the negotiations that removed long-standing trade restrictions around bovine spongiform encephalopathy (BSE) to allow more than $13 million in exports. Finally, they were significant in retaining our $168.7 million wheat exports to Brazil and Kenya by conducting outreach around flag smut.

APHIS also leads several pest control programs in the Americas designed to reduce or eliminate populations of pests like Screwworm, Mediterranean fruit fly (Medfly), and Mexican fruit fly (Mexfly). These pests can impact trade if they are found here in the United States, and although we have battled a number of fruit fly outbreaks this year, it could have been far worse without this pro-active work beyond our borders.

I could fill several more pages with the work we are doing around the world to maintain markets and foster new opportunities overseas, but I hope what I have shared underscores the priority APHIS places on exports, and you can expect more of the same in 2016.

Dr. Jere Dick, Associate Administrator, USDA APHIS 

Friday, February 12, 2016

Internet Propels Invasive Species

By Chris Bennett, Farm Journal Technology and Issues Editor.  AgWeb. 
 Friday, February 12, 2016

Ten websites, 50 days and 2,625 plant species for sale at the click of a button. Specimens were sold in 55 different countries spread across the globe. … Of the 2,625 species up for grabs, 510 were invasive. Hang on for the kicker. Out of the 510 invasive examples, 35 are on the International Union for Conservation Nature’s 100 worst invasive species list.   

The Internet has merely compounded a deeply rooted problem for agriculture. 

Karan Rawlins, Invasive Species Coordinator at The Center for Invasive Species and Ecosystem Health, is quoted throughout the article. 


Friday, January 8, 2016

Possible opportunity for PhD students working with Invasive Species to gain international experience in Ireland

Two PhD studentships are being solicited to work on an Irish EPA funded three‐year project led by Institute of Technology, Sligo and partnered with Queen's University Belfast and INVAS Biosecurity, to tackle IAS problems with multiple approaches.

Invasive species are a global problem.  The European Union has ramped-up efforts to enhance collaboration and cooperation between member countries and to improve their abilities to reduce introduction, spread and impacts of invasive species. 

To that end, the EU has initiated several Cooperation in Science and Technology (COST) Action projects focused on invasive species, one of which is COST Action 1209  European Information System for Alien Species  The aim of COST Action TD1209 is to facilitate enhanced knowledge gathering and sharing through a network of experts, providing support to a European IAS information system which will enable effective and informed decision-making in relation to IAS. An overarching priority will be to identify the needs and formats for alien species (AS) information by different user groups and specifically for implementation of EU 2020 Biodiversity Strategy. Correspondingly early warning tools and rapid response protocols will be developed. 

Center Co-Director Douce has been participating in this and other Invasive Species-focused COST Action projects to gain an understanding of EU approaches to dealing with Invasive Species and to look for possibilities of exchanging information and information technology capabilities that would be beneficial to all parties involved.

The call for applicants came through the COST Action TD1209 communications systems.  
Students will join a range of research projects on invasive species being conducted by these partners to tackle IAS problems with multiple approaches. Each PhD will benefit from research and training in a truly inter-disciplinary environment with further opportunities to collaborate with ecologists, engineers, geographers, sociologists, state agencies, government and regulators, industry stakeholders and local communities.

One PhD will be based at IT Sligo and the other in QUB. Applications can be made to one or both of these PhDs before January 22nd 2016.

PhD 1
Institution: CERIS Research Centre, Institute of Technology, Sligo

Supervisors: Dr. Frances Lucy (IT Sligo), Prof. Jaimie Dick (QUB) and Dr. Joe Caffrey (INVAS Biosecurity,Ltd.)

This PhD student will: (1) address systematic reviews and horizon scans of IAS issues in general and within Ireland in particular; and (2) develop communications for prevention, control and eradication of IAS. Further, the student will examine and develop IAS biosecurity protocols (e.g. surveys of vectors, IAS signage) at points of entry (e.g. ports) and, in the field, develop herbicide/adjuvant control methods for the invasive terrestrial plant, Winter heliotrope, Petasites fragrans.

Application: Submit a CV and Letter of Motivation by January 22 at 5pm to Dr Frances Lucy
Funding: This fully funded 3-year PhD studentship pays IT Sligo fees plus a stipend of Euro 16,000 per annum. Applicants must have a BSc and/or MSc in Environmental Science, Ecology (or similar discipline).

PhD 2
Institution: School of Biological Sciences, Queens University Belfast

Supervisors: Prof. Jaimie Dick (QUB), Dr. Frances Lucy (IT Sligo) and Dr. Joe Caffrey (INVAS Biosecurity,Ltd.)

This PhD student will address: (1) systematic reviews and horizon scans of IAS issues in general and within Ireland in particular; (2) development of communications for prevention, control and eradication of IAS. Further, the student will develop biosecurity protocols with disinfectants, such as Virkon, using ecotoxicological methods and, in the laboratory and field, develop control and eradication methods for the invasive Asian clam, Corbicula fluminea (e.g. based on dry ice application).

Application: Prospective applicants may contact the lead supervisor, Prof Jaimie Dick at

Funding: This fully funded 3-year PhD studentship pays UK University tuition fees (currently £4,052 per annum) and stipend of £14,057stg per annum. Applicants must have a BSc and/or MSc in Ecology (or similar discipline), or equivalent qualifications.​

Dr. Frances Lucy,
Director of CERIS,
School of Science,
Institute of Technology, Sligo,
Ash Lane,
Phone: +353-719305693

Board Member: Inland Fisheries Ireland

Thursday, January 7, 2016

Can the use of prescribed cattle grazing be an effective way to manage certain invasive weeds in rangeland? Results of a 6 year California pasture-scale trial.

Introducing cattle grazing to a noxious weed-dominated rangeland shifts plant communities
J.S. Davy, L.M. Roche, A.V. Robertson, D.E. Nay and K.W. Tate. 
California Agriculture 69(4):230-236. DOI: 10.3733/ca.v069n04p230. October-December 2015.

Invasive weed species in California's rangelands can reduce herbaceous diversity, forage quality and wildlife habitat. Small-scale studies (5 acres or fewer) have shown reductions of medusahead and yellow starthistle using prescribed grazing on rangelands, but little is published on the effects of pasture-scale (greater than 80 acres) prescribed grazing on weed control and plant community responses.

This study provides the results of a 6-year collaborative study of manager-applied prescribed grazing implemented on rangeland that had not been grazed for 4 years. Grazing reduced medusahead but did not alter yellow starthistle cover. Medusahead reductions were only seen in years that did not have significant late spring rainfall, suggesting that it is able to recover from heavy grazing if soil moisture is present. Later season grazing appears to have the potential to suppress medusahead in all years. In practice, however, such grazing is constrained by livestock drinking water availability and forage quality, which were limited even in years with late spring rainfall. Thus, we expect that grazing treatments under real-world constraints would reduce medusahead only in years with little late spring rainfall. After 10 years of grazing exclusion, the ungrazed plant communities began to shift, replacing medusahead with species that have little value, such as ripgut and red brome.

Wednesday, January 6, 2016

Phytophthora ramorum can survive introduction into finished compost

S. Swain and M.M. Garbelotto.  California Agriculture 69(4):237-241. DOI: 10.3733/ca.v069n04p237. October-December 2015.

Phytophthora ramorum, the causal agent of the disease sudden oak death has killed millions of trees on the north coast of California. An introduced pathogen both in North America and Europe, it was discovered in California in 1995. P. ramorum often forms lethal bark lesions on oaks (Quercus spp.) and the related tanoak (Notholithocarpus densiflorus), but it spreads by spores formed on foliar lesions on scores of other plant species, including common landscape plants. New foliar hosts have been discovered annually since 2002, and the symptoms can vary substantially from host to host.   The disease keeps spreading to new locations through limited-distance natural dispersal, infected nursery stock and perhaps through other yet unknown means To help prevent the spread of the pathogen to new localities, movement of infected plant material is highly regulated.   Debris from infected plants is almost certainly taken to local composting facilities, which are subject to restrictions on shipping product out of the quarantine area if found to be not pathogen-free.  Finished compost has a well-established history of suppressing a variety of plant pathogens when incorporated into potting mixes or planted into soil.  The survival of P. ramorum in finished compost, however, had not previously been evaluated.  The purpose of this research was to address the question of whether P. ramorum may have a high survival rate in finished compost if reached by dispersal propagules that may be transported by wind or water from fresh green waste or infectious plants within or near composting facilities.

The results show that P. ramorum may be present and infectious if introduced into finished compost, and that variations in compost characteristics appear to influence survival rates.

Monday, January 4, 2016

Comparing Invasibility to Degree of Invasion in Habitats

A unified approach for quantifying invasibility and degree of invasion, an article in Volume 96, Issue 10 (October 2015) of Ecology. Authors are Qinfeng Guo, Songlin Fei, Jeffrey S. Dukes, Christopher M. Oswalt, Basil V. Iannone III, and Kevin M. Potter.
Here is the abstract: "Habitat invasibility is a central focus of invasion biology, with implications for basic ecological patterns and processes and for effective invasion management. “Invasibility” is, however, one of the most elusive metrics and misused terms in ecology. Empirical studies and meta-analyses of invasibility have produced inconsistent and even conflicting results. This lack of consistency, and subsequent difficulty in making broad cross-habitat comparisons, stem in part from (1) the indiscriminant use of a closely related, but fundamentally different concept, that of degree of invasion (DI) or level of invasion; and (2) the lack of common invasibility metrics, as illustrated by our review of all invasibility-related papers published in 2013. To facilitate both cross-habitat comparison and more robust ecological generalizations, we clarify the definitions of invasibility and DI, and for the first time propose a common metric for quantifying invasibility based on a habitat's resource availability as inferred from relative resident species richness and biomass. We demonstrate the feasibility of our metric using empirical data collected from 2475 plots from three forest ecosystems in the eastern United States. We also propose a similar metric for DI. Our unified, resource-based metrics are scaled from 0 to 1, facilitating cross-habitat comparisons. Our proposed metrics clearly distinguish invasibility and DI from each other, which will help to (1) advance invasion ecology by allowing more robust testing of generalizations and (2) facilitate more effective invasive species control and management."

Sarah Workman did a rewrite of the research article for eXtension.
Invasive Plants’ Success Depends on Native Species Richness and Biomass