Talk About Invasive Species

I know I now sound like a complete hypocrite.  I grow nonnative species in my garden, yet I advocate the control of invasive species.  Let me explain...

According to "Plants of the Chicago Region" there are 2530 species of wild plants in my region.  Of these 1638 are native species and 892 introduced species.  Of the 892 introduced species only ~121 are listed by the Chicago Botanical Garden as either being invasive or being evaluated for invasiveness.

http://www.chicagobotanic.org/research/conservation/invasive/chicago/

There are many plants, like my Antirrhinums, that have been used in gardens for decades without becoming invasive.  These plants that have a history of disappearing in the face of competition do not give me much concern.

In contrast, there are other species that are unquestionably invasive.  I try to be responsible and remove these from my landscape.

The species that might become invasive in the future are the ones that leave me the most conflicted.  A good example is Panayoti's barberry.  It is not listed as invasive in Colorado and may never become a real problem in that climate.  It definitely has the potential since it is highly invasive in the Midwestern and Eastern States.  

I have one Berberis thunbergii in my garden that I have not yet eliminated.  I did not eliminated it because it never flowered.  This made it difficult for me to key out the species.  I now believe it is a variety (probably of hybrid origin) of Berberis thunbergii that is sterile.  If it is uncapable of reproducing then should I get rid of it?  I see no good reason to remove it.

Another example is Mark's Euonymus alatus 'compactus.'  This variety is subtly different than the variety that has escaped into our woodlands.  Even though the species has proven invasive, I do not feel justifiable in telling Mark he should remove his shrub.

A personal example that is leaving me conflicted is Spirea x bulmalda 'goldflame.'  I planted it knowing that it was not invasive in my area.  However, I later learned that Spirea japonica is invasive in the slightly warmer climates found East and South of my area.

http://www.nps.gov/plants/alien/fact/spja1.htm

Since it has not proven invasive in my area yet, should I remove it?  It definitely has the potential to become a problem in the future.  Especially with global warming.  Will the other hundreds of thousands of other specimens in my area also need to be removed?

There are species that the Chicago Botanical Garden has not included that also spread to natural areas.  I have seen Syringia vulgaris and Cornus mas escaped into our natural areas.  Does this mean these species should be added to the invasive species list?  Honestly, it would likely be easier to control them where they have invaded natural areas than try to convince people to get rid of all their lilacs.  I personally enjoy the smell of lilacs each Spring.

Other species that are highly invasive are not given legal status because of political reasons.  Panayoti listed some grasses.  Locally, Asian Lonicera has been a huge problem.  However, this species continues to be sold by nurseries.  It is so popular that preventing its sale has become difficult even though it causes great damage to our natural areas.

Most of the questions I have posted are rhetorical.  I do not expect or desire answers.  I just hope this gives you some idea as to why I am insistant that certain species should be controlled, whereas I grow other nonnative species in my own garden.

Sincerely,

James

Quote:

  I am realizing I cannot convince you that grazing has an ecological benefit. 

If cattle are valid replacements for bison in a grazing ecology, then Japanese barberry is a valid replacement for any native plant.

Try The Buffalo Book by David Dary for a description of the differences between bison and cattle.

Bob

Quote:

Most of the questions I have posted are rhetorical.  I do not expect or desire answers.   

Well, sorry.
From my perspective as Poster Boy for Gardening With Native Plants, people who indulge in "nativist" rhetoric like this really have no business growing any plants not native to their immediate area.

Bob

Two issues, involving introduced species in Nevada have to do with grazing and wild fires.  One link promotes grazing to reestablish native vegetation thus enhancing biodiversity in wild fire affected areas. The other link is a more highly charged issue, involving uncontrolled grazing by feral horses and it's detrimental effects on biodiversity.

http://www.nevadarangelands.org/research.html
http://www.fws.gov/sheldonhartmtn/sheldon/horseburro.html

Weiser,

    The links you posted have lots of excellent information.  The link on over grazing from Wild Horses/Burros demonstrates the importance of letting rangeland rest.  Only using one management regime like grazing, or no grazing, has been shown to lead to a reduced level of biodiversity.
    The link by the Nevada Rangeland Commission has lots of good information.  The paper "Livestock Grazing After Wildland Fire" is interesting.  At the end of the third page in this paper they state

"There is considerable research indicating seeding, especially aerial seeding, into areas dominated by cheatgrass will have limited success unless the competition with cheatgrass is lessened (Young 2006).  As a result, early spring grazing may be beneficial in reducing competition from annual grasses and allow for better recovery of existing plants and establishment of seeded plants (Sanders, 2000).  In this instance, early grazing while cheatgrass is actively growing but native vegetation is dormant, both the seed production of cheat grass and competition for moisture and nutrients could be lessened."

    I also find the information about Sage Grouse habitat to be particularly interesting.  It mentions fire suppression (leading to succession) and unregulated grazing practices, among other factors like agriculture, mining, urbanization, predator control, weed invasion (which wild fire can encourage) etc. as factors that have changed the sage brush ecosystem.  Here are some quotes from this paper I find to be particularly relevant.

"Research has shown that grouse select grazed meadows over ungrazed meadows (Neel 1980, Evan 1985, Klebenow 1985)"

"An optimum meadow for grouse would be one that is grazed in a fashion that enables sage grouse to select the cover height they prefer."

"In addition to reducing vegetation height, grazing improves the quality of the food plants eaten by sage grouse."

Thanks for sharing these information packed websites.

Sincerely,

James

James wrote:

I have one Berberis thunbergii in my garden that I have not yet eliminated.  I did not eliminated it because it never flowered.  This made it difficult for me to key out the species.  I now believe it is a variety (probably of hybrid origin) of Berberis thunbergii that is sterile.  If it is uncapable of reproducing then should I get rid of it?  I see no good reason to remove it.

Today I took a look at my last barberry.  Sadly, I discovered it had flowered and formed three berries.  I searched the internet and believe this barberry is variety 'cherry bomb.'  It was so different from the other barberries that were present when I bought my house that I thought it was a different species.  There is a species native to the Eastern US, Berberis canadensis.  I wanted to make sure my identification was correct before I eliminated my plant.  If it is invasive then it must go.  That is ... unless Japan wants it back.  I will probably replace it with a Diablo Ninebark or maybe one of those bush St. John's Worts we were discussing previously.

Oddly enough, when I was weeding I found a barberry seedling with leaves that were spinulose-dentate.  This is a characteristic of Berberis vulgaris (which is banned because of the Wheat Rust issue) and Berberis canadensis.  In all likelihood this seedling was a Berberis vulargis.  This is odd since I did not have a Berberis vulgaris in my garden.

Sincerely,

James

Birds eat barberry berries and disperse seed far away.