I cringe at the term "invasive" as it implies intent on the part of the plants. In the natural world, plants and animals fill available niches. Often, niches are available because humans have destroyed the native habitat or thrown it so far out of balance that 'all bets are off". The plants and animals that move in are aggressive colonizers for a reason. IMHO, that reason is to populate the barren or disrupted ecosystem rapidly and establish some kind of balance again. After severe disruption, such as urban development or crop cultivation, it is difficult or nearly impossible for a balanced ecosystem to be reestablished. The "cost" of "invasive" plants and animals is measured in the effect they have on the economic activity of humans. IMHO, the rhetoric about these plants "destroying" ecosystems is pseudoscience. They do not invade balanced or pristine natural ecosystems, but rather (human) disrupted environments. Natural systems will absorb new species and, in the process of time, integrate them into the ecosystem, but that is only if the ecosystem in question is healthy and generally balanced already. A monoculture or severely disrupted ecosystem (lawns, parks, cropland, abandoned lots, overgrown previously developed areas, etc.) is not an honest venue to assess whether a plant or animal is "invasive".

That being said, when planting new plants, gardeners need to be responsible and realize that their gardens are not balanced ecosystems. Because this is true, seemingly innocent or harmless plants can demonstrate their ability to be aggressive colonizers in such an environment. So the gardener must maintain the balance with deliberate work, or the plants will make their own balance whether you like it or not!

Point well taken LariAnn. The intro paragraph does state "Did you know most plants that are considered invasive are the result of human activities?" with the word "considered" being key. We all need to be aware and responsible when making changes to our environments.

I live in Kudzuland - much of West Alabama is carpeted in Kudzu. My own property is over-run with Asian wisteria, trumpet creeper, autumn clematis, poison ivy, privet, etc. I fully understand that this is a result of a damaged ecosystem--the activities of former owners, my neighbors, city workers, Alabama power tree trimming practices as well as a less than vigilant gardener. Now what?

So far the best solution Ive seen is Permaculture -- which is a practice for restoring ecosystems (or replacing ecosystems) so that our lands will serve our needs as well as the needs of wildlife around us, whose habitats have also been destroyed by our human activities. But the why's and hows seem to be lacking in transplanting the ideas to local situations.

Thanks for the article, Chris.

hazelnut said:So far the best solution Ive seen is Permaculture

I've been studying permaculture for a couple years now and have concluded that it is the solution for our wrecked ecosystems. When the majority turns around and concludes that it's time to restore our environment, permaculture principles will lead the way toward that restoration.

Chris, nice introductory article on "invasive plants". I'm sure quite a few folks will benefit from reading it.
Lari Ann, thanks for your post, it's an education in itself and a perspective not many people seem to have grasped yet. I'll be sure to share it with friends and gardening customers of mine.

Dave, and slightly off-topic...gonna write an article on permaculture sometime? And give some book references? And if you write it in layman's terms and down to earth (no pun intended) like you did your vermicomposting article I bet many people will get on the bandwagon!

Again, Chris, thanks for bringing up this topic!
Shoe

Yes, permaculture articles are indeed in the works.

Yayy! Thanks!

LariAnn said: They do not invade balanced or pristine natural ecosystems, but rather (human) disrupted environments.

That's wishful thinking, frankly. There are a multitude of exotic plants that are fully capable of invading intact native ecosystems and severely disrupting how they function (e.g. leafy spurge, spotted knapweed, phragmites, purple loosestrife, sericea lespedeza, caucasian bluestem, saltcedar, giant knotweed, whitetop, the list seems endless). It never ceases to surprise me how dismissive some gardeners are of the very concept of invasiveness. I think it often boils down to the simple fact that they want to be able to grow whatever they like, regardless of the consequences for the rest of us. That's disappointing. You would think gardeners, of all people, would have more regard for the natural world than that.

I would like to see actual scientific studies demonstrating that any exotic plant has successfully "invaded" a genuinely pristine ecosystem and disrupted it. All of the plants you mentioned have "invaded" areas that were or are disrupted already by human activity. If you can find a true pristine ecosystem that hasn't been disrupted by humans now or in the past, then you can research this question. Otherwise, I suggest refraining from the panicky hyperbole that is more characteristic of pseudoscience than reasoned research.

Even in island situations (for example, a fresh volcanic island barren of plant life), all the plants and animals that colonize it are "exotic". How can they be "native" when there are no native flora on such a new volcanic island? Yet they come, colonize and, over time, establish a balanced ecosystem, unless humans come in and disrupt it.

For further reading, see "Invasion Biology - Critique of a Pseudoscience" by David Theodoropoulos http://www.invasionbiology.org...

Here's another source of information with references and slides to accompany it. Mentioned are several of the alleged "most invasive" plants and the scientific reasons why the hysteria is unfounded. A thorough read of this paper will provide the reader with an informed point of view.

http://dtheo.org/AABGAPaper.ht...

Your link is just an internet rant by David Theodoropoulos, a seed dealer who has been heavily criticized for ignoring noxious weed laws among other things. Basically, he believes he has the right to ship the seeds from any plant anywhere he pleases, regardless of the law. The most amusing thing about it is that the vast majority of papers cited his "Literature Cited" section actually document the damage caused by invasive species. You'd be better off reading the papers themselves rather than trusting his bizarro world interpretation of them.

I'm having deja vu all over again... last winter/spring, on either DG or GardenWeb forums, a very similar conversation took place (as I recall, that person said the rush of invasives was just another facet of evolution).

Sometimes we get so caught up in the academics of an issue that we ignore the practical side of it (same could be true in reverse, I guess). We can get all tied up in knots about whether a plant is truly invasive, about *why* plants are invasive, and whether the word "invasive" is even the correct terminology. None of that addresses the issue of non-native water plants are choking the waterways, or kudzu across open fields and jumping from tree to telephone pole to next tree with abandon.

Responsible gardeners need to recognize and admit that not every species of plant is appropriate for their location. The resources that Chris provided are good starting points. There are lots of things I would like to plant that either remind me of my original home or just look beautiful, but I choose to research before planting, and avoid those listed as invasive for my state/area. I'm lucky in that I don't have to battle kudzu in my own yard, but it's all around my area and is a never ending battle down here.

As humans, we're never going to live in an area where humans have not interfered with an ecosystem. If using the term "invasive" is what's needed to help people understand "OMG DON"T PLANT THAT HERE!" then it's the correct term, even if it's technically incorrect.



Just my 2cents -- feel free to disregard.