[APWG] Invaders

[Marc Imlay]

A Report on the Progress of Invasive Plant Control Program 

 

Maryland Native Plant Society, Anacostia Watershed Society and 

Sierra Club Habitat Stewardship Committee Report 

 

Non-native invasive species of plants such as English Ivy, Japanese
Stiltgrass and Kudzu are covering the natural areas that we in the
conservation movement have worked so hard to protect from habitat
destruction, erosion and water pollution.  Just as we are making progress on
wetlands, stream bank stabilization, and endangered species, these plants
from other parts of the world have typically covered 20-90% of the surface
area of our forests, streams and meadows. Many of us feel demoralized and
powerless to combat these invaders that have few natural herbivores or other
controls. 

 

The Maryland Native Plant Society, Anacostia Watershed Society and Sierra
Club are establishing a program to provide local groups and public and
private landowners with several models to draw upon in the region. We are
assisting in developing a major 5 year work effort at each site to remove
massive populations of about a dozen species. Regular stewardship projects
are conducted in all seasons including winter, early spring, late spring,
summer, and late summer.  This high-intensity program is followed by a
low-intensity annual maintenance program to eliminate plants we have missed,
plants emerging from the seed bank, and occasional plants migrating in from
neighboring areas. We announce regular monthly projects at over 40 sites in
Maryland almost all of which were initially started as a result of
on-the-ground workshops conducted by current MNPS members in Charles County
and Montgomery County. The Nature Conservancy has also conducted projects on
natural areas for many years. MNPS and the Sierra Club sponsor the monthly
projects at Chapman Forest (800 acres), Swann Park (200 acres) and Greenbelt
National Park (1.5 square miles). They co-sponsor Little Paint Branch Park
(150 acres) and Cherry Hill Road Community Park (15 acres) removals in
Beltsville and Magruder Park in Hyattsville MD (15 acres) with the Anacostia
Watershed Society and provide considerable assistance to the other projects.


 

These sites serve as a visible example of what can be accomplished. 

 

The biggest challenge is to ensure that in subsequent years all the
successful projects are carried on by responsible entities. Our advice to
others considering similar projects are to recognize that restoration of our
native ecosystem is realistic but requires an appropriate level of work
effort. 

 

Many of us have done extensive surveys of this area and find that at least
80% of the natural areas are salvageable with a combination of mechanical
and carefully targeted chemical control and no requirement for
re-vegetation. The natives return on their own since they initially covered
the majority of the surface area. We remove all the class 1 and class 2
exotic species, typically 5-20 species, because otherwise if you just
eradicate one exotic another one may replace the one removed. 

 

Our policy is to use carefully targeted, biodegradable herbicides in natural
areas, such as glyphosate and triclopyr, that do not migrate through the
soil to other plants. Instead of spraying invasive trees such as Ailanthus,
Norway Maple, and Chinese Privet we inject concentrated herbicide into the
tree either by basal bark, hack and squirt or cut stump. Seedlings are easy
to hand pull. We wait for wet soil after a rain to hand pull, first
loosening with a garden tool such as a 4 prong spading fork so the center of
the plant rises perceptively. At the 200 acre Swann Park, where we are
essentially in maintenance phase after 5 years, 17 of the 19 non-native
species are eradicated or nearly so. Only Japanese Stiltgrass and Garlic
Mustard remain serious. 

 

All the methods, techniques and/or findings of these projects can be used
where the initial cover of non-native invasive species is less than 30% of
the total plant cover and adequately where under 70% cover. At higher
percent coverage the chemical component is more overwhelming and native
plant re-vegetation may be necessary with native species that are not
cultivars and are obtained from the wild or from nursery stocks originally
collected locally in the wild. There are several well researched species
mixes that include 12-16 herbaceous and shrub species including nitrogen
fixers. 

 

Marc Imlay , PhD Conservation biologist, Anacostia Watershed Society 

301-699-6204, 301-283-0808

Board member of the Mid-Atlantic Exotic Pest Plant Council, 

Hui o Laka at Kokee State Park, Hawaii 

Vice president of the Maryland Native Plant Society, 

Chair of the Biodiversity and Habitat Stewardship Committee 

for the Maryland Chapter of the Sierra Club. 

Remember our five year goal: It is considered standard that such invasive
plant removal projects are normally done throughout the region, the nation,
and the world. 

 

 

 

-----Original Message-----
From: apwg-bounces at lists.plantconservation.org
[mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Bob Beyfuss
Sent: Friday, September 12, 2008 10:15 AM
To: Michael Schenk; apwg at lists.plantconservation.org
Subject: Re: [APWG] Invaders

 

Hi All

There is no question that globalization has dramatically accelerated the 

spread of invasive species but I really do not see any possibility at all 

of that situation changing in the future. In fact, it is likely to become 

much worse in the next few decades. The question that arises, is how do we 

react?  I don't think that simply declaring "war" on all invasive species 

anywhere they occur and at whatever rate of infestation is the answer. The 

older I get, the less convinced I am that war is the answer for most of our 

problems.  I would prefer a more thoughtful approach targeting protection 

of specific and highly sensitive ecosystems instead of ill advised 

eradication programs that are doomed to failure before they begin. The 

Director of our local Nature Conservancy told me that he could spend 90% of 

his entire budget for the next three years, attempting to eradicate 

roadside garlic mustard with the only certain outcome that he would have to 

start all over again in 3 years. When I see eradication programs conducted 

in highly disturbed urban environments I wonder if the cost justifies the 

temporary results. Ultimately, the disturbances that led to the invasions 

remain and often the results of widespread herbicide applications only 

insure that the problem. Unless the entity that is applying any herbicide 

against invasives can reasonably predict that the outcome of that 

application will result in the desired reestablishment of the plant 

community it is designed to protect, I question the action. In simple 

terms, killing invasive plants simply because "they are there" with no real 

clue as to what will follow, is bad policy.

Bob

 

 

At 11:49 AM 9/11/2008, Michael Schenk wrote:

>Bob, thanks for the article.

> 

>This article contains an excellent summary of the unprecedented threat of 

>the modern spread of invasive species: the vastly accelerated rate of 

>invasion, coupled with the stress placed on ecosystems by induced rapid 

>changes. Read through to the latter part, past the feel-good stuff about 

>the fossil record. Of course the fossil record doesn't contain anything 

>comparable. There was no highly mobile technological species imposing 

>geological rates of change in decades as opposed to millions of years.

> 

>Change in species diversity and ranges happens constantly. It's the rate 

>of change which is worrisome. The rate of change from a major asteroid 

>strike, scaled in weeks or years, is more similar to the current rate of 

>change than the megayears we'll find in the fossil record.

> 

>Mike

> 

> 

> >Message: 1

> >Date: Wed, 10 Sep 2008 14:53:13 -0400

> >From: Bob Beyfuss <rlb14 at cornell.edu>

> >Subject: [APWG] Fwd: Friendly Invaders

> >To: apwg at lists.plantconservation.org

> >Message-ID:

> >       <6.2.1.2.2.20080910145256.051d6008 at postoffice8.mail.cornell.edu>

> >Content-Type: text/plain; charset="iso-8859-1"

> >

> >

> >>X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6

> >>Date: Tue, 09 Sep 2008 14:11:52 -0400

> >>X-PH: V4.1 at granite2

> >>To: rlb14 at cornell.edu, <jrh45 at cornell.edu>

> >>From: Gary Goff <grg3 at cornell.edu>

> >>Subject: Fwd: Friendly Invaders

> >>X-PMX-Version: 5.3.1.294258, Antispam-Engine: 2.5.1.298604,
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> >>>X-PH: V4.1 at granite2

> >>>X-PH: V4.1 at tulip

> >>>To: CCE-INVASIVESPECIES-L at cornell.edu

> >>>From: "Robert J. Kent" <rjk13 at cornell.edu>

> >>>Subject: Friendly Invaders

> >>>Cc: Charlie Scheer <cfscheer at optonline.net>

> >>>X-PMX-Version: 5.3.1.294258, Antispam-Engine: 2.5.1.298604,

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> >>>Reply-To: "Robert J. Kent" <rjk13 at cornell.edu>

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> >>>X-LYRIS-Message-Id:

> >>><LYRIS-7370812-3026195-2008.09.09-08.57.30--grg3#cornell.edu at list.corne


> ll.edu>

> >>>

> >>>NY Times

> >>>September 9, 2008

> >>>

> >>>

> >>>

> >>>

> >>>Friendly Invaders

> >>>

> >>>

> >>>

> >>>

> >>>

> >>>By 

> <http://query.nytimes.com/search/query?ppds=bylL&v1=CARL >>>ZIMMER&fdq=199


> 60101&td=sysdate&sort=newest&ac=CARL

> >>>ZIMMER&inline=nyt-per>CARL ZIMMER

> >>>

> >>>New Zealand is home to 2,065 native plants found nowhere else on Earth.

> >>>They range from magnificent towering kauri trees to tiny flowers that

> >>>form tightly packed mounds called vegetable sheep.

> >>>

> >>>When Europeans began arriving in New Zealand, they brought with them

> >>>alien plants ? crops, garden plants and stowaway weeds. Today, 22,000

> >>>non-native plants grow in New Zealand. Most of them can survive only
with

> >>>the loving care of gardeners and farmers. But 2,069 have become

> >>>naturalized: they have spread out across the islands on their own.
There

> >>>are more naturalized invasive plant species in New Zealand than native 

> species.

> >>>

> >>>It sounds like the makings of an ecological disaster: an epidemic of

> >>>invasive species that wipes out the delicate native species in its
path.

> >>>But in a paper published in August in The

> >>><http://topics.nytimes.com/top/reference/timestopics/organizations/p/pr


>
oceedings_of_the_national_academy_of_sciences/index.html?inline=nyt-org>Proc
eedings 

> 

> >>>of the National Academy of Sciences, Dov Sax, an ecologist at

> >>><http://topics.nytimes.com/top/reference/timestopics/organizations/b/br


> own_university/index.html?inline=nyt-org>Brown

> >>>University, and Steven D. Gaines, a marine biologist at the University
of

> >>>California, Santa Barbara, point out that the invasion has not led to a

> >>>mass extinction of native plants. The number of documented extinctions
of

> >>>native New Zealand plant species is a grand total of three.

> >>>

> >>>Exotic species receive lots of attention and create lots of worry. Some

> >>>scientists consider biological invasions among the top two or three

> >>>forces driving species into extinction. But Dr. Sax, Dr. Gaines and

> >>>several other researchers argue that attitudes about exotic species are

> >>>too simplistic. While some invasions are indeed devastating, they often

> >>>do not set off extinctions. They can even spur the evolution of new 

> diversity.

> >>>

> >>>?I hate the ?exotics are evil? bit, because it?s so unscientific,? Dr.

> >>>Sax said.

> >>>

> >>>Dr. Sax and his colleagues are at odds with many other experts on

> >>>invasive species. Their critics argue that the speed with which species

> >>>are being moved around the planet, combined with other kinds of stress
on

> >>>the environment, is having a major impact.

> >>>

> >>>There is little doubt that some invasive species have driven native

> >>>species extinct. But Dr. Sax argues that they are far more likely to be

> >>>predators than competitors.

> >>>

> >>>In their new paper, Dr. Sax and Dr. Gaines analyze all of the
documented

> >>>extinctions of vertebrates that have been linked to invasive species.

> >>>Four-fifths of those extinctions were because of introduced predators

> >>>like foxes, cats and rats. The Nile perch was introduced into Lake

> >>>Victoria in 1954 for food. It then began wiping out native fish by 

> eating them.

> >>>

> >>>?If you can eat something, you can eat it everywhere it lives,? Dr. Sax

> >>>said.

> >>>

> >>>But Dr. Sax and Dr. Gaines argue that competition from exotic species

> >>>shows little sign of causing extinctions. This finding is at odds with

> >>>traditional concepts of ecology, Dr. Sax said. Ecosystems have often
been

> >>>seen as having a certain number of niches that species can occupy. Once

> >>>an ecosystem?s niches are full, new species can take them over only if

> >>>old species become extinct.

> >>>

> >>>But as real ecosystems take on exotic species, they do not show any
sign

> >>>of being saturated, Dr. Sax said. In their paper, Dr. Sax and Dr.
Gaines

> >>>analyze the rise of exotic species on six islands and island chains.

> >>>Invasive plants have become naturalized at a steady pace over the last

> >>>two centuries, with no sign of slowing down. In fact, the total
diversity

> >>>of these islands has doubled.

> >>>

> >>>Fish also show this pattern, said James Brown of the

> >>><http://topics.nytimes.com/top/reference/timestopics/organizations/u/un


> iversity_of_new_mexico/index.html?inline=nyt-org>University

> >>>of New Mexico. He said that whenever he visits a river where exotic
fish

> >>>have been introduced, ?I ask, ?Have you seen any extinctions of the

> >>>natives?? ? ?The first response you get is, ?Not yet,? as if the

> >>>extinction of the natives is an inevitable consequence. There?s this

> >>>article of faith that the net effect is negative.?

> >>>

> >>>Dr. Brown does not think that faith is warranted. In Hawaii, for
example,

> >>>40 new species of freshwater fish have become established, and the 5

> >>>native species are still present. Dr. Brown and his colleagues

> >>>acknowledge that invasive species can push native species out of much
of

> >>>their original habitat. But they argue that native species are not

> >>>becoming extinct, because they compete better than the invasive species

> >>>in certain refuges.

> >>>

> >>>These scientists also point out that exotics can actually spur the

> >>>evolution of new diversity. A North American plant called saltmarsh

> >>>cordgrass was introduced into England in the 19th century, where it

> >>>interbred with the native small cordgrass. Their hybrid offspring could

> >>>not reproduce with either original species, producing a new species

> >>>called common cordgrass.

> >>>

> >>>Long before humans moved plants around, many plants hybridized into new

> >>>species by this process. ?Something like a third of the plant species
you

> >>>see around you formed that way,? Dr. Sax said.

> >>>

> >>>Biological invasions also set off bursts of natural selection. House

> >>>sparrows, for example, have moved to North America from Europe and have

> >>>spread across the whole continent. ?Natural selection will start to

> >>>change them,? Dr. Sax said. ?If you give that process enough time, they

> >>>will become new species.?

> >>>

> >>>?The natives themselves are also likely to adapt,? Dr. Sax added. Some
of

> >>>the fastest rates of evolution ever documented have taken place in
native

> >>>species adapting to exotics. Some populations of soapberry bugs in

> >>>Florida, for example, have shifted from feeding on a native plant, the

> >>>balloon vine, to the goldenrain tree, introduced from Asia by
landscapers

> >>>in the 1950s. In five decades, the smaller goldenrain seeds have driven

> >>>the evolution of smaller mouthparts in the bugs, along with a host of

> >>>other changes.

> >>>

> >>>In Australia, the introduction of cane toads in the 1930s has also

> >>>spurred evolution in native animals. ?Now that you have cane toads in

> >>>Australia, there?s a strong advantage for snakes that can eat them,?
said

> >>>Mark Vellend, of the University of British Columbia. Cane toads are

> >>>protected by powerful toxins in their skin that can kill predators that

> >>>try to eat them. But in parts of the country where the toads now live,

> >>>black snakes are resistant to the toxins in their skin. In the parts

> >>>where the toad has yet to reach, the snakes are still vulnerable.

> >>>

> >>>Dr. Brown argues that huge negative effects of invasions are not

> >>>documented in the fossil record, either. ?You see over and over and
over

> >>>again that this is never the case,? he said. Species have invaded new

> >>>habitats when passageways between oceans have opened up or when

> >>>continents have collided.

> >>>

> >>>?The overall pattern almost always is that there?s some net increase in

> >>>diversity,? Dr. Brown said. ?That seems to be because these communities

> >>>of species don?t completely fill all the niches. The exotics can fit 

> in there.?

> >>>

> >>>In a recent paper in the journal Science, Peter Roopnarine of the

> >>>California Academy of Sciences and Geerat Vermeij of the University of

> >>>California, Davis, looked at the history of invasions among species of

> >>>mollusks, a group that includes mussels, clams and whelks. About 3.5

> >>>million years ago, the mollusks of the North Pacific staged a major

> >>>invasion of the North Atlantic. Before then, the Arctic Ocean had
created

> >>>a barrier, because the mussels could not survive in the dark,

> >>>nutrient-poor water under the ice.

> >>>

> >>>A period of

> >>><http://topics.nytimes.com/top/news/science/topics/globalwarming/index.


> html?inline=nyt-classifier>global

> >>>warming made the Arctic less forbidding. Yet the migration did not lead

> >>>to a significant drop in the diversity of the Atlantic native mussels.

> >>>Instead, the Atlantic?s diversity rose. Along with the extra exotic

> >>>species, new species may have arisen through hybridization.

> >>>

> >>>The Arctic Ocean is now warming again, this time because of human

> >>>activity. Computer projections indicate it will become ice-free at
least

> >>>part of the year by 2050. Dr. Roopnarine and Dr. Vermeij predicted that

> >>>today?s mollusks would make the same transoceanic journey they did 3.5

> >>>million years ago. They also expect the invasion to increase, rather
than

> >>>decrease, diversity.

> >>>

> >>>But critics, including Anthony Ricciardi of

> >>><http://topics.nytimes.com/top/reference/timestopics/organizations/m/mc


> gill_university/index.html?inline=nyt-org>McGill

> >>>University in Montreal, argue that today?s biological invasions are

> >>>fundamentally different from those of the past.

> >>>

> >>>?What?s happening now is a major form of global change,? Dr. Ricciardi

> >>>said. ?Invasions and extinctions have always been around, but under
human

> >>>influence species are being transported faster than ever before and to

> >>>remote areas they could never reach. You couldn?t get 35 European
mammals

> >>>in New Zealand by natural mechanisms. They couldn?t jump from one end
of

> >>>the world to another by themselves.?

> >>>

> >>>It is estimated that humans move 7,000 species a day. In the process,

> >>>species are being thrown together in combinations that have never been

> >>>seen before. ?We?re seeing the assembly of new food webs,? said Phil

> >>>Cassey of the University of Birmingham in England. Those new
combinations

> >>>may allow biological invasions to drive species extinct in unexpected 

> ways.

> >>>

> >>><http://health.nytimes.com/health/guides/disease/botulism/overview.html


> ?inline=nyt-classifier>Botulism,

> >>>for example, is killing tens of thousands of birds around the Great

> >>>Lakes. Studies indicate that two invasive species triggered the
outbreak.

> >>>The quagga mussel, introduced from Ukraine, filters the water for food,

> >>>making it clearer. The sunlight that penetrates the lakes allows algae
to

> >>>bloom, and dead algae trigger an explosion of oxygen-consuming
bacteria.

> >>>As the oxygen level drops, the botulism-causing bacteria can multiply.

> >>>The quagga mussels take up the bacteria, and they in turn are eaten by

> >>>another invasive species: a fish known as the round goby. When birds
eat

> >>>round gobies, they become infected and die.

> >>>

> >>>?If you pour on more species, you don?t just increase the probability

> >>>that one is going to arrive that?s going to have a high impact,? Dr.

> >>>Ricciardi said. ?You also get the possibility of some species that

> >>>triggers a change in the rules of existence.?

> >>>

> >>>Dr. Ricciardi argues that biological invasions are different today for

> >>>another reason: they are occurring as humans are putting other kinds of

> >>>stress on ecosystems. ?Invasions will interact with climate change and

> >>>habitat loss,? he said. ?. We?re going to see some unanticipated 

> synergies.?

> >>>

> >>>Both sides agree, however, that decisions about invasive species should

> >>>be based on more than just a tally of positive and negative effects on

> >>>diversity. Invasive weeds can make it harder to raise crops and graze

> >>>livestock, for example. The Asian long-horned beetle is infesting
forests

> >>>across the United States and is expected to harm millions of acres of

> >>>hardwood trees. Zebra mussels have clogged water supply systems in the

> >>>Midwestern United States. Exotic species can also harm humans? health.

> >>>?<http://health.nytimes.com/health/guides/disease/west-nile-virus/overv


> iew.html?inline=nyt-classifier>

> >>>West Nile virus,

> >>><http://health.nytimes.com/health/guides/disease/the-flu/overview.html?


> inline=nyt-classifier>influenza

> >>>? these things are invasions,? Dr. Ricciardi said.

> >>>

> >>>On the other hand, some invasive species are quite important. In the

> >>>United States, many crops are pollinated by honeybees originally

> >>>introduced from Europe.

> >>>

> >>>?It?s not that this is all good or all bad, and I?m not sure science

> >>>should be the arbiter,? Dr. Brown said. ?Placing values on these things

> >>>is the job of society as a whole.?

> >>

> >>-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:


> -:-:-:-:-:-:-:-:-:-:-:-

> >>

> >>Gary R. Goff

> >>104 Fernow Hall, Cornell University, Ithaca, NY 14853.

> >>ph. 607/255-2824;  fax 607/255-2815;  e-mail: grg3 at cornell.edu

> >>www.cornellmfo.info

> >>http://www.dnr.cornell.edu/people/ra/profiles/goff.html

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