The dangers of planting 'Exotic Invasives'

I'm not really looking to open up a can of worms here. I simply want to give an anecdote that illustrates why I feel we should think twice before planting exotic invasives. I'm not completely against this practice but I feel that some people don't take it seriously enough. This is an effort to get people to think twice before going ahead with such plantings. Please read on...

Here in central ontario, canada we have an outbreak of European Buckthorn. It was brought in as an ornamental and then 'escaped'. I highly doubt that whoever planted it here in Canada could have imagined that the following problems would result, much as I think most of us planting other exotics think that such problems will arise.

Two huge problems that the Buckthorn in Canada creates:

1) The Buckthorn berries are a laxative. They are eaten by birds who then deficate to the point of dehydration and often death. According to a friend in the conservation authority game, its a huge problem.

2)This plant is rampant. It grows in just about any condition (shade, sun, dry, wet, poor and rich soil etc.) and the more you try to cut it, or dig it out, the more shoots come up. It shades/chokes out native plants, taking up probably millions of square feet of nature which could be occupied by ANYTHING else and be better for it.

I am aware to some degree of the debate circling this subject, and its sensetive nature. I've read David Jacke's Edible Forest Garden Book which talks about the other side of the coin, and asks 'where do you draw the line as to what is exotic or not'(eg. is a seed that blows across the ocean an exotic?) He illustrates that indigenous cultures of north america (for example) did a fair amount of moving plants around, and I am not opposed to this. I just want to give some food for thought.

I completely agree we should be very careful what we plant to make sure it will not be invasive in our locale.  There's generally a non-invasive choice we can make, but in any case, invasives should be avoided like the plague they are.

Personally I consider monoculture fields of anything to be "exotic invasives" including large fields of grain. 

Travis, you are talking about rhamnus cathartica, right? I never heard of birds being poisened by its fruits. In Europe rhamnus catharitica is one of the most important plants for birds at all. Normally only slow digesting animals (like humans) show poisoning effects from its fruits.

European buckthorn has the ability to change soil rapidly to an environment more suitable for nitrogen loving plants but they don't thrive in full shade. Partially shade and full sun is their place to live. They are outcompeted by oaks, spruces and other trees which grow well under a thick cannopy.

Dunkelheit, I'll have to ask my conservation authority friend about her source. She's in the business of being informed about such things, and informing landowners about such things, so I took her word on it.

Having spent much time reading the accounts of archaeologists, predominantly from the Neolithic and Bronze Ages, I have read of the effects of hunter gatherer groups, as they wandered and foraged, spreading seeds from one area to another, as well as the effects of the early agriculture movements of men. What you may think is native plant life of an area, according to your current historical knowledge, may well be not native, in the grand scheme of things. Some seeds found at archaeological sites from several thousand years ago, are not what is considered native now.

Add to that, the effects of migrating animal life, carrying seed from furs or droppings and you can easily see that "native" is a relative term. Climate change is also having an effect. Plants that would not previously survive in one zone, now are not only surviving, but spreading. A friend of mine here in Montana, originally from the south and used to cardinals, saw his first, in 20 years, up here in Montana last spring and others this spring. In the old alpine regions of Old Europe (Neolithic) there is evidence of the climate change, similar to what we are going through now. As it got warmer, alpine regions began dying off, and the aspens, which thrive in the die off areas of the alpines, spread. That created a different habitat, causing other wildlife to prosper there and that changed the plant life.

There is apparently a small vineyard near/or in Missoula that everyone told them they could not grow grapes up here. But all the old timers have stated that the winters have been milder and that is allowing those grapes to survive where they would not have in many years past. 500 years from now, someone may be worried about the native buckthorn, in Ontario, disappearing and some other invasive arriving on the scene.

Here's a link to a list of invasive species in Canada from the Canadian Government site.

http://www.ec.gc.ca/eee-ias/78D62AA2-55A4-4E2F-AA08-538E1051A893/invasives.pdf

It includes Buckthorn. It doesn't say that native birds are killed, they just don't eat it, which given fewer sources of food isn't going to help them.

The (introduced) European Starlings are immune to the poison, so help spread the seeds... So we can blame New York's Shakespeare fans

It also includes information on how to remove invasive plants.

People in my region (Central Texas) are sometimes confused about our native Ashe Juniper (called "Cedar") - some people think it is an invasive exotic.  It tends to quickly take over fields that are overgrazed, so it acts like an invasive exotic, but it is indeed native, it just used to be confined to steep canyons or other areas where the prairie fires couldn't reach it.  But now most of the prairie is gone, it is taking over huge tracts of land.  It's a useful and beautiful tree, but can be at times too much of a thing.  Many people are allergic to the pollen, another reason it is disliked.  Some people claim it "steals water" but personally I consider it to be more of an indicator of bad land management rather than it being bad itself. 

And here in lies the rub for sure.

I was planning on exotics when I begin to plant my forest garden, because although my area is native-forest it is NOT a garden-forest.  It is pine desert in dry regions and pine/brush in wet ones.  I cannot live off of that native ecology with only a few acres. 

The thing is, when someone plants a species they cannot know what changes lie ahead that might cause that species to escape and become invasive, as Kathryn points out.

I agree that being careful is very important, however that is looking a bit vague.  Maybe we could discuss what guidelines one should follow when intentionally planning on species not 'native'? 

To start with - I think looking at similar regions, ecologies and latitudes can help guide us in possible planting outcomes, and plants to maybe avoid, or at the least watch very closely. 

What ideas do you all have for exotic guidelines to avoid invasive situations as much as possible?

Most states in the US have a list of invasives, so I would start there, I think.

http://www.invasivespeciesinfo.gov/index.shtml

Thanks Ludi, that's is a good resource, but I already have a listing of invasives for my region. 

I was wondering more about plants that haven't become invasive (listed) yet. . . .

I'm so good at killing just about anything I plant, I like to look for things that claim to be "easy to grow" but avoid things that "spread quickly."  Things that are invasive for other people have not been for me (so far) - like Jerusalem Artichokes.  Looking at the invasives list for the area and avoiding plants that are closely related to some invasives might be a good idea.  Such as members of the Spurge family seem to often become invasive. Maybe looking at similar climates in other parts of the world and seeing what has become invasive there. 

New Zealand is pretty much overwhelmed by introduced species.
For every gorse, (absolutely loathed by farmers but a valuable nitrogen-fixer and nurse plant for natives), there's honeysuckle: (a major problem in the bush with no redeeming features whatsoever. Oh, it smells nice).
I'm interested in other people's take on invasive/opportunistic plants.
"I'll  remove the fruit/seeds/suckers forever" seems at best naive to me.
What happens when you move, or die?
Over here you're always within bird-crapping distance of the bush, so I'm mindful of planting dodgy stuff that'll strangle and poison.

Kathryn, in regards to your post:

I realize that humans and animals have played a historical role in plant dispersal. I am simply calling for caution when doing so. I feel that just because we have the ability to do something, and a history of doing it, doesn't mean that we necessarily should. There are simply too many cases where humans have brought plants to new places, resulting in total havoc.

I agree that the term exotic is a bit muddy in this case. To me it means something that is not historically or currently known to have grown in a given place. I realize that this is flawed because of the limitations of our historical and current knowledge but it is the best I can figure personally.

Jami:

My guidelines are to use native species whenever possible to fill the niches I wish to create, and when natives won't suffice, I will go on to choose non-native, non-invasives. When I still have a niche I wish to create but the above won't suffice, I ask myself 'do I really need this niche'? If I felt I really needed this, then I would consider exotic invasives after looking at its behaviour in similar climates as the one I am in. If it is shown to find a role in these similar ecosystems without annihilating other species, then I would probably go for it as well.

Travis, thanks for laying out your process.  That helps.

Travis, I fully understand your perspective and have tried to deal more with natives  when possible. I used to live in Texas and have seen the devastation that many new plants and insects have caused to the land and wildlife, based on what we know now. I personally would like to obliterate fire ants. And having lived a few years in Nebraska, I can attest to the invasive Russian Thistle, also known as the tumbleweed.

I can see both sides of the issue and as a researcher of a wide variety of archaeology studies, have seen invasive versus native issues come up for a host of things. Such as mesquite, which is everywhere in the southwest, used by bees, by livestock for fodder, food and medicine for people, useful for the furniture industry, wood chips for smokers, etc., but archaeologists have shown that mesquite was not native to that area and they can date when it first starts appearing in sites. What did it displace and how much time did it take to find so many of the beneficial uses for it?

Enjoying many wild edible and medicinal wild plants, I like to find the uses for as many things as possible, such as a variety of goosefoot that that removes salt from the soil and transpires it to the leaves, which when burned can be added to soap to make it hard for the bars. For me, it is a challenge to find the myriad of uses for plants, rather than look at them as invasive and a thorn in the side. Surely some capitalistic company could find certain properties and uses for the hated buckthorn in Canada and next thing you know, they will be growing it intentionally.

From a systems perspective, or from a natural history perspective, we can say that ecosystems change ... to a degree, increasing the number of species is how things work. But the human impacts on the species composition of ecosystems is often so great that it has lots of undesirable effects.

Adding new species is generally not as bad as habitat destruction or fragmentation, but it can be quite negative. Thoughtful restraint is a good policy.