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Hey guys, I'm new to your forum and I love the information I'm finding on it. Can't wait to hear what you guys think of my question.

I have an honest question which is not meant to stir anything negative up. I know some people feel strongly about invasive species.

I completely understand why, with globalization and the ease of access to foreign plants, it is more important now than ever before to be careful which new species we introduce when gardening. I also understand though that over the course of time immemorable plants have spread across the continents and if we had looked back through the centuries, each new species to arrive in a region would have been considered an invasive species.

I think, as most people do, that the natural course of ecosystem evolution (without any human intervention) is the best option, but since people have already and will probably continue to introduce invasive species to various regions... How do we differentiate between which new "invasive" species are naturally occurring ecosystem progression and which are introduced by humans and require human intervention to prevent their spread?

I know it would be easy to identify some human-introduced invasive species based on the vast distance between their native habitat and their new habitat, but that's not the case for all.

Thanks guys I'm very interested to hear other people's opinions on this.

it's not as complicated as it sounds. If something evolved where it is, even if it is spreading in to new areas naturally, it is part of a very complex web of natural relationships, checks and balances, things that eat it, things it eats, diseases and pests that control it. It may be somewhat aggressive growing, but it won't destroy the landscape.

If something is plopped down somewhere it doesn't "belong," it is not part of any of those relationships. Nothing can use it, nothing controls it. Then it becomes the landscape equivalent of a cancer, spreading rapidly, taking over all the resources, choking everything else out. The trouble with foreign invasives isn't that they are foreign, it is that they degrade the landscape and turn what was an amazingly complex forest or other ecosystem, into a mono-culture, where nothing much exists but it. Have you ever seen an area kudzu has taken over?

https://images.harc.edu/Sites/GalvBayInv ... 624015.jpg

kudzu - all those shapes were trees. Now they are dead, as are all the things that used to rely on those trees and live there. Kudzu so far is not very frost tolerant and in the US is mostly confined to the southeast.

But then there is mile-a-minute vine, sometimes called kudzu of the north:


https://www.mam.uconn.edu/JHGoldstein.jpg

The name is only a slight exaggeration. It can grow six inches in a day.

from the above article:

Mile-a-minute can cause major ecological problems:
—overgrows and outcompetes other plants, shading out native vegetation
— forms dense mats interfering with forest regeneration and seedling establishment

So, naturally occurring species, even if they spread, bring all their relationships with them. All these invaders don't, which is part of why they can take over like that. So what was a forest, with birds and butterflies, squirrels and foxes, animals from beetles to maybe even bears, wildflowers, shrubs, trees, producing wood, nuts, fruits, berries, is killed and none of that exists anymore.

So that's my test -- does it "belong," are there naturally occurring species in the area that can use it, eat it, prey on it, control it? Does it contribute anything to the ecosystem it is in or only take from it?

PS Welcome to the Forum and thanks for the thoughtful question.

Most states have invasive species list and post it on the web. The problem with bringing in plants from other parts of the world is that if it is in a favorable environment and is not controlled it can spread. This becomes a real problem when the biological controls that control it in its' natural environment don't exist in yours. It takes years for the state to test before importing biological controls since they need to ensure that it won't do more harm than good.

Besides, in Hawaii, everybody knows about what happened after the state decided to import the mongoose and axis deer.

Hawaii 's most invasive plant species list is below.

https://www.state.hi.us/dlnr/dofaw/hortw ... eslist.htm

We went out today and dug up a bunch of supposed weeds, (in this province). I too have heard people

shouldn't plant this stuff in their gardens, but they are all tough plants, flower when most things have quit.

Plus are very pretty. They will be going in my flower bed's. Right now we just healed them in, after giving

them a good drink of water. So many of these plants have gorgeous flowers on them.

I decided that I want things that are really tough, and won't give up, when other plants do. We got

everything I wanted today, I am so happy. I know I'm probably bad, but these plants will live.

what are these weeds (what kind of plants)? Most truly aggressive, invasives do not have showy flowers.

"weeds" can mean a lot of things. Native wildflowers are often called weeds when they show up in people's gardens too, but that isn't what I'm talking about.

If you don't know what you have, post some pictures here, so people can identify them for you. I think it is important to know what they are, to know what conditions they should be planted in, how to take care of them, and what to expect from them, including whether or not they are likely to take over your yard/ the planet.

I wish everyone who gardens would read Sara Stein Noah's Garden and/or Doug Tallamy Bringing Nature Home. They are wonderful on why it is important to plant native species and how much difference people can make just by planting their yard with natives.

I second rainbowgardener!

Remember, too, that what is "growing well despite the harsh conditions" -- somewhere out there -- could become VERY COMFORTABLE in your more fertile, less competition, loose and less compacted soil garden beds.

The other day, I saw large round scalloped leaves on a weed growing in the midst of my corn patch where I have been diligently applying nitrogen-rich fertilizer and wondered what it was. The leaves were at least 2 inches in diameter. Looking closer, I recognized the thin vine they were growing on -- it was GROUND IVY/CREEPING CHARLEY which in the lawn only grows to 1" leaves at the most. When I pulled it up -- it did come up easily like ground ivy does -- almost 2 feet of it came slithering out of the corn.

A lot of these "weeds" are actually flowers that have been brought into the province, years ago and not only

survived, but thrived, but only in certain areas. I have been keeping track of these flowers for the last 3

years, just watching what area, they grow in, plus soil conditions, also how they spread.

They seem to stay in the same areas, not spreading a lot. What kind of plants they are I have no idea?

I unfortunately can't take pictures right now, as our camera is still packed. Our grandson's phone camera is

not working. Got dropped one to many times.

But if I can borrow a camera somewhere, I will go take pictures of the plants, where we got them. They only

seem to be in certain areas. So obviously don't spread everywhere. I really don't think they are actually

weeds, more like plants brought in yrs ago. Some are probably native plants?

Unfortunately my book on plants in Alberta is still packed as well. I'm going to try and find it, then hopefully

I can get back to you on what I have? Now I'm really curious too.

That book sounds very interesting. Sounds like a good read.

Sara Stein is a much more engaging writer, Doug Tallamy is more academic, but they cover a lot of the same ground. Your library would have the books.

I will call and see if they have it. Thanks.

English ivy is a tree killer.