Invasive Plant News

The Midwest and Great Lakes Chapter of the Society for Ecological Restoration (SER) had its chapter meeting at the University of Michigan in Ann Arbor earlier this month.  These conferences are wonderful mix of presentations - by students, professors, lay-people, not-for-profit leaders and business representatives. 

Participants got a closer look at the eastern massasauga rattlesnake. Photo by Stephen Glass

I have been to conferences and meetings of all kinds. It always impresses me how lively, open and welcoming these SER chapter meetings are.  Student presentations and posters draw the same attention (and hard questions) as given to presentations of established experts.

One of the highlights of the conference was a visit to the Matthaei Botanical Gardens.

An eastern massasauga rattlesnake lying in the grass. Photo by Stephen Glass.

A major part of the Gardens have been restored to provide habitat for the eastern massasauga rattlesnake (Sistrurus catanatus catenatus), a protected species in Michigan. This restoration effort is a complex undertaking. Restoration techniques have to be adjusted and customized. For example, in many areas the snake uses habitat that includes non-native bluegrasses (Poa compressa, P. pratensis). Only after sufficient area of more mature native prairie habitat has been created can the bluegrass dominated areas also be converted to native prairie. In fact, the area where we saw the snake was dominated by bluegrasses.

The Annual Meeting Committee deserves enormous credit for putting on a great meeting and recruiting those eastern massasauga rattlesnakes that made their appearances! The Committee members include:

• Young D. Choi, Purdue University Calmulet (chairperson)
• David Benson, Director of Environmental Studies and Assistant Professor of Biology, Marian College
• Hua Chen, Associate Professor of Biology, University of Illinois, Springfield
• Cody Fleece, Stantec Consulting Services
• Robert Grese, Professor and Director of the Matthaei Botanical Gardens and Nichols Arboretum. University of Michigan
• Jennifer Lyndall, ENVIRON International Corporation
• Pamela Rice, PR Environmental Consulting
• Rocky Smiley of the USDA ARS Soil Drainage Research Unit
• Donald Tilton, Environmental Consulting & Technology, Inc.

A recent article in the Star Tribune, a Minnesota newspaper, highlights two related risks of pesticide applications – drift and volatilization.  The article doesn’t deal with invasive species, and the chemical of concern is a fungicide, not an herbicide.  Nevertheless, the article does point out the importance of controlling drift and volatilization from pesticide applications – which of course are commonly used to control invasive species.

The investigation was spearheaded by the Pesticide Action Network (PAN) and concerned the use of the fungicide chlorothalonil on potato crops.  In an effort coordinated by PAN, residents near potato fields in northwestern Minnesota set up and checked 19 monitors at schools, in yards, and on porches.  The monitoring revealed low concentrations of the fungicide in the air in and around the town of Perham, Minnesota, 68 percent of the time during the monitoring period. 

One troubling aspect is that the concentrations of the fungicide in the air appear to have resulted from legal applications of the fungicide according to Linda Wells, the Midwest Coordinator for PAN of North America.  It appears therefore that the chlorothalonil moved off-site some time after application such as by volatilization, i.e., the fungicide changed to a gas after application.  This is concerning because it may be hard to correct the problem.

The United States Environmental Protection Agency (EPA) is currently reviewing health risks from the inhalation of chlorothalonil.  In addition, EPA’s Office of Research and Development has launched a research program to assess Drift Reduction Technology.   

However, until EPA acts, officials at the Minnesota Department of Agriculture, indicate there are few options.  This is troubling since Minnesota state health officials find the data credible.  The Star Tribune article quotes Rita Messing, a toxicologist with the Minnesota Department of Health’s division of environmental health who is familiar with the findings.   Messing says “We are inclined to believe it until there is other data that is better.”

Invasive plants take advantage of late

Common buckthorn (Rhamnus cathartica),forming grean background, retains its leaves late into the fall.

season photosynthesis by keeping their green leaves later in the fall than native plants.  This is the finding of a recent study by Jason Fridley published online in Nature.  The study compared related deciduous species such as Japanese honeysuckle (invader) and Canada honeysuckle (native), burning bush (invader) and bursting heart (native), and European buckthorn (invader) and Carolina buckthorn (native).

 According to Fridley, this concept “was totally off of everybody’s radar.”  However, anybody who has worked to control an invasive species like common buckthorn (Rhamnus cathartica) has long known that this late season persistence makes the non-native easy to identify for treatment.  Common buckthorn is the tree with green leaves in the late fall.

What’s new that the study offers is that these invaders continue to photosynthesize for almost four weeks longer in the fall than their native counterparts.   It is not certain that this gives the non-native species an advantage.  For example, the non-natives lose a source of nitrogen when their green leaves fall off before nitrogen still in the green leaf is absorbed into the stem and roots.  According to Fridley, the invaders may have co-evolved with another invader, Eurasian earthworms, which speeds decomposition of leaves  and may bring the nitrogen back into the invasive plant.

 I don’t find this hypothesis convincing (although I have no data to back up my position).  I have seen common buckthorn thrive in sandy soils with few earthworms.  Couldn’t it just be that an invasive like buckthorn gains more by photosynthesizing longer than it loses by dropping green leaves?  Each year as the growing season extends due to global warming, invasive species such as buckthorn improve their advantage.

An opinion piece in the Canberra Times by Julian Cribb, an Australian science and agriculture writer, paints this bleak image of the future of the Austrailian natural world:

“By the end of this century it is possible that Australia will be gone for good, immersed in a green tide of alien vegetation, pests and shifting climatic regions. It may well still be sunburned and afflicted (more frequently) by drought and flooding rains, but the quintessential Australian landscape that has defined this continent for millions of years and was the backdrop to both Aboriginal and European settlement, will largely no longer exist.”

Cribb attributes a major role in this transformation to the more than 30 new alien species of plants and pests introduced every year in Australia.  Is the future this bleak in Australia?

On this past Saturday morning, the St. Paul Parks and Recreation

Volunteers with some of the garlic mustard

Department sponsored a garlic mustard pull in Como Park.  The pull was in the area that is in the Como Woodland Outdoor Classroom.  According to the website: “This classroom will provide environmental education and historical interpretation for school children and adults, habitat for native wildlife, and an urban

Jack-in-the-pulpit doing its best to compete with all that garlic mustard; we evened things out a bit.

woodland oasis for the inner-city community where local place-based, hands-on environmental learning opportunities are rare.” It was a little rainy, but the event still attracted over 50 volunteers and several groups such as one from Fedex. It was really encouraging to see native species – such as the jack-in-the-pulpit in the photo – that are hanging on despite the competition from invasives.

This article is part of a series of articles about people who demonstrate exceptional (and often unheralded) commitment to protecting natural areas threatened by invasive plant species.

How does Lisa Brush, Executive Director of the Stewardship Network in Ann Arbor, Michigan, deal with gloomy conservation forecasts?  She goes to work and immerses herself in a world where people are doing something right now to prove those forecasts wrong.

The Stewardship Network works to protect, restore, and manage  natural

Lisa at Barton Park overlooking the Huron River - a place to recharge.

lands and waters of the Great Lakes region by helping individuals, organizations, and businesses manage specific natural areas.  It helps by finding ways to share ideas, resources, and information.  In the same way that wildlife corridors link wildlife habitat, the Stewardship Network links the people trying to protect and restore that habitat.

One of the Stewardship Network’s first projects was assisting a group of residents and teachers and students at Eberwhite Elementary School in Ann Arbor in the early 2000s.  The objective was to protect the Eberwhite Woods, a 29 acre native oak-hickory forest which has never been clear-cut.  The group had the will, but they didn’t necessarily know the way to protect the unique forest ecology.  Lisa and the Stewardship Network helped by bringing in experts such as Bob Grese, the Director of the Matthaei Botanical Gardens and Nichols Arboretum at the University of Michigan.  Today, the woods thrive, and just as importantly, the students and teachers in Eberwhite and the Woods Committee remain deeply engaged.

In 2011, the Stewardship Network partnered with 152 groups and had 10,648

Lisa in earlier days pulling garlic mustard with a little help from her daughter Isabel.

participants at its events.  The Stewardship Network has established local collaborative conservation communities known as “Stewardship Network Clusters.”  For example, the Headwaters Cluster was the first Cluster, established in 2003.  The Michigan Chapter of the Nature Conservancy helped the Stewardship Network bring together people interested in protecting ecosystems in Oakland County, an area home to the headwaters of six different river systems threatened by extreme development pressures.

The Stewardship Network also links interested parties, not just in the Great Lakes Region, but around North America with its free monthly webcasts.  The webcasts can focus on control of specific invasive species such as “Swallow-Wort” (this month’s webcast) or on often neglected topics like organizing volunteer days or handling environmental conflict (the human kind).  I have participated in the webcasts, and they are wonderful– not one-sided presentations but lively exchanges of ideas from participants around the country.

Then, there is the Garlic Mustard Challenge.  People pull garlic mustard and report the number of pounds of garlic mustard pulled to the Challenge website.  This year’s goal is 200,000 pounds.  Anyone, anywhere can participate.  Erin Mittendorf, one of Lisa’s colleagues at the Stewardship Network, observed, Lisa’s most valuable contributions are made amongst us.  What Lisa does best is bring people together.  That is our biggest challenge.  As Arne Witt said in an earlier article on Lantana, “the problem is not managing invasive species, it is managing people to manage invasive species.”  And, maybe that is why Lisa doesn’t get bogged down by those gloomy conservation forecasts.  Instead, she sees and further spurs the hope in people that those gloomy forecasts are wrong.

Here’s a link to a really nice article in the New York Times on the Weed Warriors.  They are working to clear Edgewood Park in San Mateo County, California, of various invasives including Yellow Star thistle, teasel, broom, and Italian thistle.

Conservationists are “fighting a losing battle” against invasive plant species such as Lantana (Lantana camara L.).  That is the conclusion of  a team of researchers

Lantana camara Forest & Kim Starr, U.S. Geological Survey, Bugwood.org

from the University of Oxford and the University of Bergen in their article entitled: “A Battle Lost?  Report on Two Centuries of Invasion and Management of Lantana camara L. in Australia, India and South Africa.”  According to the authors this means the “established paradigm” of eradication of invasive species must be abandoned in favor of “adaptive management.”

I discussed the article with two people who have been working for years on invasive plant species in Australia and Africa.  Rod Randall and Arne Witt.  Rod Randall works for the Department of Agriculture and Food, Western Australia.  Arne Witt works for CABI based in Nairobi, Kenya.  (See biographies below.) 

The very first thing that Randall and Witt questioned about the Lantana article was the existence of any “established paradigm of eradication” for entrenched invasive species such as Lantana.  As Randall observes, “it shows a certain naivety on the part of the authors that anyone would consider control attempts in Australia, India or South Africa as eradication efforts.”  Lantana first invaded in the 19^th century.  Back then, control efforts only occurred after invasive plants had become massive problems.  It is now so well established that eradication of an established invasive such as Lantana is out-of-the-question – at least with current means.

Both Randall and Witt argue that control is the key with well-established invasives like lantana.  And both agree that control is not a lost cause.  Interestingly, they contend the problem is not so much the invasive species as it is the people in charge.  As Witt says, “a wise man once told me that the problem is not managing invasive species but managing people to manage invasive species. This is so true if you look at past efforts that have been made to manage infestations around the world.”  

As Witt relates, “I was personally involved in a project in Zambia where the government made $450,000 (U.S. dollars) available to clear Mimosa pigra from a floodplain in a National Park.” The national implementing agencies had no real structured plan or strategy for follow-up activities, but the government promised to make more funding available when current funds were depleted, so, as Witt notes, “nobody was too concerned.”  After more than 900 ha. of a 3,000 ha. infestation were cleared, funds dried up and the area is being re-invaded.  “Without knowing the details someone may say that the management of Mimosa pigra in Zambia has been an absolute failure,” and “the weed is impossible to control.”  According to Witt, however, “this is far from the truth – it was a failure of management/people, but important lessons have been learned in this process.  There are many examples where we can effectively control weeds if we develop long-term control strategies coupled to long-term sustainable funding – it is not a lost cause.”

Randall describes just such a success: involving Kochia (Bassia scoparia (L.) A.J.Scott).  This effort worked “because the critical people, the landholders . . . were right behind the program and worked well with our agency to remove Kochia from over 2700 acres and hundreds of widespread sites.” (Note this eradication program cost less than $500,000 (Australian dollars) and was deemed successful after 10 years of monitoring with no finds.) 

In short, there really is no “established paradigm” of eradication according to Witt and Randall for established invasives like lantana.  It is a straw man that distracts and discourages decision-makers such as government agencies.

And what do the Oxford and Bergen researchers mean by “adaptive management” of invasive plant species?  In a future article, Invasive Plant News will address this topic.

Arne Witt: Arne has been working on the management of invasive plants, particularly biocontrol, for the past 18 years. He has worked for CSIRO (Australia), Queensland Department of Natural Resources and Mines (now Biosecurity Queensland), the Plant Protection Research Institute of the Agricultural Research Council (South Africa), and is currently the Regional Coordinator (Africa and Asia) for IAS for CABI. He has been the International Project Coordinator and/or Technical Advisor for GEF-UNEP IAS Projects in Africa, SE Asia and the Caribbean assisting in the strengthening/development of IAS policy, creating awareness, building IAS capacity and the development and implementation of control programmes for IAS.

Rod Randall: A biologist by training, Rod started his career with the Western Australian Agriculture Protection Board in 1985 moving to the Department of Agriculture’s Weed Science group in 1987.  In 2002 he published A Global Compendium of Weeds the most comprehensive document on the status of the worlds weed flora.  Rod has worked extensively on weed biology and ecology for a quarter century and for the past 16 years has assessed all plant introductions into Western Australia for their weed potential.  In that time he has assessed over 10,000 species and extensively reviewed the weed status of many hundreds of others.

“Everything is everywhere, but the environment selects.”  This concept regarding microbes is attributed to Lourens Baas Becking, the Dutch botanist and microbiologist.  Functionally the theory posits that microbes are not limited by dispersal.  Since the nineteenth and early twentieth century, this principle has been challenged.  It is challenged in a recent article entitled “Interactions between exotic invasive plants and soil microbes in the rhizosphere suggest that ‘everything is not everywhere’” published in the Annals of Botany.

Authors Rout and Callaway make two observations based on a review of past studies: “First, in their non-native ranges invasive plants commonly interact differently with the same soil microbes than native plants. Second, in their native ranges, plants that are invasive elsewhere commonly interact functionally with soil microbes differently in their home ranges than they do in their non-native ranges.  This may help explain why some exotic invasives are more invasive in non-native ranges.  See, for example, Rout and Callaway, An invasive plant paradox.  Other research however questions the existence of this paradox.  See Firn et al.,  Abundance of introduced species at home predicts abundance away in herbaceous communities.

Most invasive plants invade environments with climates similar to their native one.  This is

Spotted knapweed (Centaurea stoebe) has spread beyond its native niche. Source: Bugwood Archive.

the conclusion reached by a team of researchers from the University of Lausanne, ETH Zurich and the University of Hawaii. Their work was just published in the journal Science.  The researchers analyzed fifty invasive plant species and confirmed that most exotic plants invade areas with a similar climate.  Only about fifteen percent of the species studied moved into climate niches outside their native niche.