Invasive versus Native Question

Discussions and news related to invasive and exotic species affecting our trees and forests.

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edfrank
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Re: Invasive versus Native Question

Post by edfrank » Wed Jun 08, 2011 9:53 am

Kouta,

Your points about the grass/herb dominated early succession and the addition of late succession non-native trees are perfectly valid points. Perhaps because you are not a native speaker you are better at considering the nuances of the language. The problem really is that there is no clear single definition of what is or is not an invasive species. Different sources provide different definition depending on how they want to apply the term to their own situation. What I posted was an attempt at a compromise among several definitions dealing specifically with whether a native species "a formerly minor species in a forest that suddenly increased its population dramatically" could be considered invasive or not. I think this is a good if not perfect explanation of this aspect of the broader concept of invasive species. These issues have been discussed here before. The definition I suggested was not meant to be the final word on what the overall definition of invasive should be, but a commentary on one aspect of the subject.

The grass and herb example you used I would not consider invasive because they are part of the natural sequences of change from one plant community to another even though the change is rapid. An alien late successional tree would be an invasive species simply because it is an alien non-native to the area.

I am always interested in your perspective on any of these issues, and so are others here. You have a different background, different experiences and bring a welcome different perspective to these discussions. My goal is to better understand the processes that are occurring in the forests and with the trees, even if it means I need to reevaluate and revise my thinking on the subjects.

The lack of a uniform definition of what is invasive is perhaps both a weakness and a strength of the scientific community here. Different people and different groups use the term differently, but since the definition is not fixed the researchers are free to try to refine the term to better match what they are actually seeing in the field without being bound by the constraints of a strict definition.

Overall it would be better if the term invasive was reserved for non-native, alien, and exotic species that were altering the overall ecosystem of an area and we had a different term for native plants that dramatically took on a more dominant role in the forest ecosystem. There isn't any such term that is commonly being used here, so for now the best term we (in my opinion) have is "native-invasive."

Ed

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"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

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jamesrobertsmith
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Re: Invasive versus Native Question

Post by jamesrobertsmith » Wed Jun 08, 2011 9:51 pm

When I think of "invasive", it's in terms of non-native species. Such as the hemlock wooly adelgid or the Asian carp, Burmese python, Kudzu, Mimosa, etc.

In reference to poison ivy, I got a healthy dose of it on my right leg when I did the hike into the Curtis Creek old growth a few weeks ago. Painful darned stuff. I think some was mixed in with the stinging nettles I waded through along the creek bank.

One of my pals who was climbing in the Black Canyon of the Gunnison NP showed me photos of vast expanses of nothing but poison ivy growing in the gullies he used to climb out of the canyon. He had to wear long pants, long sleeves, and gloves. Then wash up with good soap once he achieved the canyon rim. Apparently it's EVERYWHERE out there in that place.
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Poison ivy lesions on my right calf.
Poison ivy lesions on my right calf.

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KoutaR
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Re: Invasive versus Native Question

Post by KoutaR » Thu Jun 09, 2011 3:00 pm

Ed,

From the definition problem of invasiveness, I get to my mind the various definitions of old-growth forest and what John Davis writes about them in the foreword of Eastern Old-Growth Forests, p. xiii, lines 3-17.

I wrote an invasion could also be of natural cause. For example, if two regions with similar climates come into contact through a climate change (e.g. lowering of the sea level) or plate tectonics. Then parts of floras and faunas may colonize the other region very rapidly. Do you consider this like colonization as an invasion?

Kouta

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eliahd24
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Re: Invasive versus Native Question

Post by eliahd24 » Thu Jun 09, 2011 4:17 pm

In that case humans are the invasive species :)

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edfrank
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Re: Invasive versus Native Question

Post by edfrank » Thu Jun 09, 2011 4:31 pm

Kouta,

In paleontology (I am a geologist) these interactions because of plate tectonics or things like the land bridge established by the formation of Central America between North American and South America are usually referred to as an invasion. Like the Mongol Hordes running rampant through and across the new area available for colonization. In the case of North America and South America many North American species invaded South America. This led to the extinction of many marsupials and large predatory birds in South America. Going the other way the impact was minimal with opossums being the major species expanding into North America.

Ed
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

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jamesrobertsmith
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Re: Invasive versus Native Question

Post by jamesrobertsmith » Thu Jun 09, 2011 4:33 pm

edfrank wrote:Kouta,

In paleontology (I am a geologist) these interactions because of plate tectonics or things like the land bridge established by the formation of Central America between North American and South America are usually referred to as an invasion. Like the Mongol Hordes running rampant through and across the new area available for colonization. In the case of North America and South America many North American species invaded South America. This led to the extinction of many marsupials and large predatory birds in South America. Going the other way the impact was minimal with opossums being the major species expanding into North America.

Ed
Don't forget the brief appearance in North America of the Terror birds!

wisconsitom
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Re: Invasive versus Native Question

Post by wisconsitom » Fri Feb 19, 2016 1:57 pm

On the off chance that one or more of you guys will get back here, I've been in discussions where the term 'invasive' got bandied about. I think one way to reduce confusion is to apply the full phrase-exotic invasive-for when we wish to describe something like common buckthorn invading a Wisconsin woodlot. Otherwise, to simply say invasive is to denigrate what is after all a necessary and positive process. So, an abandoned farm field may thus be "invaded" by white pines or white cedar. Is this invasive? Well yes, it is. Is this a bad thing? No, of course not.

Then too, there is a troubling tendency today for all manner of folks to use the word invasive when all they really mean is that some plant in their yard has aggressive growth tendencies-an utterly different and often completely unrelated phenomenon. Those are the cases where I get the most frazzled....some Houzz forum I go to once in a while, the lady was screaming abut how "invasive" the Glechoma in her lawn is. Sheesh.......talk about a misappropriation of that word. I'd like to see the place where Glechoma-that's "ground ivy" or "creeping Charlie" if you will-is supplanting native species, let alone native plant communities! The word has now passed into the general consciousness, but not in a way that is at all helpful, I don't think.

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Don
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Re: Invasive versus Native Question

Post by Don » Fri Feb 19, 2016 8:27 pm

As we enter this 'gray area', I'll further explore the 256 shades of gray by adding a quote from one of our members, Steve Galehouse, whose comment following his signature is:
"every plant is a native somewhere"...
; ~ }
Don Bertolette - President/Moderator, WNTS BBS
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Joe

Re: Invasive versus Native Question

Post by Joe » Sat Feb 20, 2016 7:21 am

In the long term- think ahead centuries- just about every species on the planet will "invade" every other place it could possibly survive. The ecosystems of the planet are going to be all mixed up- then, over time, a new equilibrium will be established. It's an inevitability as much as death and taxes- whether we like it or not. Certainly this will result in the loss of some species but I think some of those future ecosystems might be rather interesting. If only we could shoot into the future with a time machine...

I read a great book some years ago- can't recall the name- but it described what happened over geological time as a result of plate tectonics- continents would collide and any species that could make the move to the other landmass would do so. It's happened over and over.

Mixing up ecosystems isn't the worse thing that can happen to the planet- what probably is much worse is too many humans.
Joe

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Bart Bouricius
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Re: Invasive versus Native Question

Post by Bart Bouricius » Mon Feb 22, 2016 7:21 am

Don,

What about Monsanto's GMO's, I think not.

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