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Invasive planting vs human contribution to evolution.


Joined: May 28, 2010
Posts: 24
Location: Zone 5a (Canada)
Firstly - as often here, I'm not sure exactly what my question is. It is something related to the risks, benefits, duties and responsibilities of introducing species.

The simple way of living is adhere to simplistic rules. Don't plant anything that hasn't been declared native, and pull up anything that has been declared introduced. However I don't want to do that. For a start I'd have to repatriate myself back to Europe, and presumably on to the Great Rift Valley, with a measurable percentage stopping off in Mongolia. Secondly I want to eat things that are not native to Southern Ontario.

So, given I've decided to break the simple rules. I need a new set of rules to follow.

A specific case study - at the moment I'm interested in 2 native North American species considered non-native in Southern Ontario - Northern Catalpa and black locust. From the official MNR documentation (Ontario Ministery for Natural Resources)... For the Northern Catalpa it asserts
"Not recommended because: Native species adapted to our local environment are always preferred to introduced species which often contribute little to our ecology and the web of life that sustains us."

For the Black Locust is asserts
"Not recommended because: Native species adapted to our local environment are always preferred to introduced species which often contribute little to our ecology and the web of life that sustains us."

This is just the simplistic rule I've decided to ignore, so the information is of little use to me. Also, from further reading, of the two, the Black Locust (fast growing, nitrogen fixer, rot resistant, high energy fuel) is criticised as very invasive, whereas Catalpa (pretty, but not much use) is mostly harmless. This further encourages me to ignore the simple rule which doesn't distinguish between them.

On the one hand 'local plants are adapted to local conditions' on the other hand 'invasive plants out compete them'. Surely the 'locally adapted plants' would have evolved a better strategy... so when that once in 100 year event comes along, bye-bye invaders, so why worry?

OR... are the local plants just not competitive enough, due to having had it too easy since the end of the last ice age without enough true competition?

OR.. the local adaptations are from 300 years ago when winters were harsher and the current set of mature trees sprouted. We should be sourcing trees from further south?

Given that human populations are living here in greater numbers than ever before, is it the duty of the most environmentally influential (vertebrate) species to dissuade monocultures by introducing new species of trees and actively managing woodlands, finding replacements for native plants that are affected by disease - for example Elm, Ash, Chestnut? Or just wait for the next ice age and see what survivors make it back up north next time?

Should we not move forward from where we are now, to a sustainable future, as opposed to attempt to return, guilt ridden, to a past perceived golden age of natural purity?

Zone 5a (Canada)
Jordan Lowery

Joined: Sep 26, 2009
Posts: 1528
Location: zone 7
ive been wondering the same thing, not sure where im at yet. i do want the natural world to go its own path and all, but i also know that if we don't start managing the woodlands as you put it and stop farming like it is now... well you know.

imo when introduced species are managed properly they completely benefit the land/ecosystem.

The ultimate goal of farming is not the growing of crops, but the cultivation and perfection of human beings. - Masanobu Fukuoka
Richard Kastanie

Joined: May 26, 2010
Posts: 74
Location: Missouri Ozarks
Black locust is a pioneer species and a nitrogen fixer and many other species grow well under it, young black walnuts will even grow under a black locust canopy while, but they need too much light to grow well under a canopy of most other trees. Yes, they grow fast and spread, so don't plant them in an area where you don't want something with those characteristics, but I consider the assertion that they're "invasive exotics" just a few hundred miles from their native range to be a bit ridiculous. Defining something as native just by where it was in 1491 is arbitrary, in fact with climate change many species will need to be able to move to survive. 12,000 years ago Ontario was under thick glaciers, and even the non-glaciated parts of North America were under a very different climate pattern and had a radically different ecosystem than now. Since we're likely to see another major climate rearrangement, trying to restrain North American species to only the places they grew in 1491 is an invitation for more extinctions and ecological degradation.

Joined: Oct 23, 2011
Posts: 0
there is another thread about this somewhere. but i agree with you.

way too simplistic, if you want a black locust go plant one, its silly to think that the local wildlife wont find how to use it and the greater diversity is always preferable in my mind.

black locust as i have read is only 'probably' a nitrogen fixer.

im not sure if an introduced chestnut blight really betters our argument but it certainly strengthens the case for diversity.

as you say the rule is too simplistic so ignore it. most funny how we spend so much money to eliminate life forms on this earth, and this is just another example. i can think of little better about modern society than that we can bring every species of plant wherever we feel it can benefit mankind (and for the same reasons it will benefit animals)

i do not believe this holds true with animals tho. particuarly predators. predators should never be introduced without starting at the bottom of the food chain. add the prey smallest first and build up and i think that is better than releasing your boa. but i still don't think its worth it. domestication, fine maybe but a predator could wipe out a population. plants dont do that
Matt Ferrall

Joined: Dec 26, 2008
Posts: 555
Location: Western WA,usda zone 6/7,80inches of rain,250feet elevation
Invasives are some of the most adapted of plants to a particular environment.If they are also useful than perfect.I think people need to be present in thier relationships with the landscape around them.Global warming is destabilizing ecosytems and if we are not here to guide them to paridise than we will just end up with the lame/de fault invasives.Not doing anything or riding the fence is no longer an option.Full speed ahead onto the unknown!

There is nothing permanent in a culture dependent on such temporaries as civilization.
John Polk

Joined: Feb 20, 2011
Posts: 6879
Location: Currently in Seattle. Probably moving 1 hour north by end of the year.
I feel that the entire Native/Introduced argument is a two edged sword.  Some imported plants have caused havoc in many areas (kudzu in the southern US comes to mind).  I look at the many uses (and value) of Black Locust, and think that it is a tree that any homesteader should consider.  If its so-called invasive nature causes native species to retreat, then perhaps, it is more adapted to the climate, and would be a better choice than the native.  If they cannot compete, should we continue to coddle them?  It is just a matter of time before something else would push them out.
Leila Rich

Joined: May 24, 2010
Posts: 3999
Location: Wellington, New Zealand. Temperate, coastal, sandy, windy,
I'm in New Zealand and we have thousands of very well-established introduced species and the majority are  much more aggressive than natives.
Our climate is temperate, and most introduced things here came from the Northern hemisphere, where cold winters at least slowed them down!
It's not native vs introduced for me: I grow loads of exotic plants. It's more being aware of how insane some things can be when they're out of their natural habitat, minus natural predators and climatic 'brakes'.
I am wary of the effects bringing things into an environment can have.
When I was a kid, we moved to very isolated place that had avoided many of the really aggressive  introduced things.
Now the place is swamped with jasmine, honeysuckle, wild ginger, apple mint, European snails and hedgehogs (yes, there is a connection!) among other things.
I have a fairly long list of things I refuse to plant, and I always keep in mind that 'control' is a bit of a  fantasy.  I can't control where the wind and birds move seed to, let alone what happens after I leave, die or stop maintanence for whatever reason.

Joined: Feb 05, 2011
Posts: 56
Humans have long been involved in seed transfer and the movement of species, intentionally and unintentionally. Did the American Chestnut expand its range through human movement? Probably. Paw-Paw? Probably. Groundnut (Apios americana)? Definitely. This is one of the ways we participate in the landscape that pre-dates industrial civilization and, well, even just regular ol' civilization. As climate destabilization continues and we see more trees having more trouble (hemlocks, western pines, ash, etc.) it may prove beneficial to become vectors for tree-species to fill these open-niches.

Certainly, at the same time, introduction can lead to destruction. The introduction of the Chinese Chestnut came with the side effect of introducing blight to the American. But these are the ways changes happen sometimes. Had that been met with a more ecological view, of letting the blight take its course (and not going on a cutting-spree of all the remaining chestnuts) there would probably be more blight resistant strands today. But regardless, the opportunities still exist for Chestnuts, but perhaps just Chinese, European, Japanese or various hybrids. Humans just need to step up and start planting them.
Fred Morgan

Joined: Sep 29, 2009
Posts: 977
Location: Northern Zone, Costa Rica - 200 to 300 meters Tropical Humid Rainforest
Since we grow a lot of trees, I have a basic criteria when it comes to exotics. We only grow two, teak and acacia. Teak because of high demand, acacia because it is nitrogen fixing and would grow in concrete I think so it is great at rapidly fixing slopes and is a good wood.

My criteria? They don't reproduce without help. Both require treatment to the seeds, or you can have a carpet of seeds, and nothing sprouts. On top of that, sheep adore the seeds, etc of acacia. After it passes through them, the seeds will sprout, but that is fine, the sheep love the seedlings even more! So, they never get out of control, I wish more would survive.

We all grow exotics - if you grow vegetables. I could wish some of my vegetables were a bit more invasive too... if you know what I mean.

Speaking of which, we grow camote (sweet potato) and it is an invasive native.  I bet none of you have problems with your sweet potatoes trying to take over your garden! I frequently go out and whack them down with my scythe and feed the vines to the sheep - and of course, we eat the vines too. Squash is another invasive plant here, and believe it or not, Lima beans!

Sustainable Plantations and Agroforestry in Costa Rica
Brenda Groth

Joined: Feb 01, 2009
Posts: 4433
Location: North Central Michigan
as Toby Hemenway says..what did you have for breakfast

was it native..

will you continue to eat it?

if so then if you can grow it, grow it, otherwise you have to buy it and that means someone else has to grow it.

first plant natives if they provide what you need, if they don't plant something close to the native if it provides what you need..but most important..plant what you eat ..what your animals prevent having to buy it

the least you buy ..the least other people have to grow your food


Bloom where you are planted.
Jan Sebastian Dunkelheit

Joined: Aug 08, 2010
Posts: 201
Location: Germany/Cologne - Finland/Savonlinna
We have tons of studies about biodiversity in Europe about introduced species from oversea. It is a fact that introduced tree species are NOT used as habitat from native insects. When you plant say a black locust in Germany which is not native to the region you have a HUGE lifeless gap in your canopy.

It's not only about resistance and plant species being outcompeted. It's about all life being pushed away. Introduced species are not interesting for native insects. Evolution took tens of thousands of years to interconnect species with one another. You're careless when you plant aggressive invasives.

But if invasive trees are adaped to wasteland you're going to cultivate - that's a different matter to me. Better to have a green near to lifeless canopy than to have no canopy at all.

Life that has a meaning wouldn't ask for its meaning. - Theodor W. Adorno
Ray South

Joined: Jul 11, 2011
Posts: 46
Location: Northern Tablelands, NSW, Australia
This issue causes me some angst and it clearly bothers many others. I avoid, where possible, planting a species I think might invade local forests/fields - this includes both exotic and native (non-local) species. If I can find a local species that will do the job I want then that's what I plant. If not, I start looking further afield. If you take into account possible impacts of various species when deciding then I think you've done the best you can. This applies not just to plants but to all species we introduce e.g., the application of legume inocula or the addition of VAM is also introducing a species.

Exotics often out compete because there are no local constraints - pests, disease and so on - to keep them in check. Here in Australia we have hundreds of introduced pests, both animal and plant, that are out of control (some might include ourselves in this). Perhaps in 10000 years local species will have evolved to make use of them and by doing so keep them in check. Until then I believe we have to manage them!
Laura Jean Wilde

Joined: Aug 03, 2011
Posts: 77
I am here looking for suggestions on whether to plant russian olive in my permaculture farm. but wow! both sides well defended and no concise opinion! anyone want to suggest whether yay or nay in SW Ontario. I'm certainly not the only person around here with them, so my decision won't destroy the local ecosystem; it's just a moral issue. You know "if I'm not part of the solution, I'm part of the problem."

Wilde on Turtle Island
Walk Gently on our Mother Earth
Suzy Bean

Joined: Apr 05, 2011
Posts: 940
Location: Stevensville, MT
Paul and Kelda continue reviewing chapter 2 of sepp holzer's Permaculture in this podcast.

They talk about invasive plants.
Yone' Ward

Joined: Feb 14, 2012
Posts: 135
Location: Springdale, WA USA - Cold Mediterranean Climate
As I understand it, Humans are the single most plentiful species on the planet and do a remarkably good job of reproducing and surviving. Unless humans either

A: Suffer a near extinction level event,
B: Transform into some kind of Human 2.0 that has nearly zero environmental impact,
C: Cheap and easy interstellar transport is invented very quickly,
D: Some or all of above,

then I believe "survival of the fittest" will require a strong "being able to play nice with/ be useful to humans/ be tougher than humans" factor regardless of whether it is an animal or plant; regardless of the values of the people involved. While I don't recommend aerial dusting with kudzu seeds, I wouldn't get overly exited about locus trees either. Invasive species will happen, so I recommend just making the best of it.

Just call me Uncle Rice.
17 years in a straw bale house.
Donovan Wentworth

Joined: Apr 14, 2012
Posts: 14
Location: Michigan - Zone 6a-5b
@Laura Jean Wilde: There are lots of native alternatives to Russian olive! It mostly depends on what purpose you want to plant Russian olive for, though.

The Natural Resources Conservation Service of North Dakota has made a useful factsheet for finding alternatives. Not all of those plants are native to Ontario, but many of them are. Several of them are food producing plants that I imagine would be perfect for a permaculture garden such as golden currant (Ribes aureum), American plum (Prunus americana. I'm sure its close relative Canadian plum, or Prunus nigra, would work just as well), highbush "cranberry" (Viburnum trilobum), hawthorn (there are hundreds of species, but I know at least the black hawthorn, Crataegus douglasii, is edible. Just don't eat the seeds as they're poisonous!), and nannyberry (Viburnum lentago, apparently edible but maybe not the greatest fruit ever). All of those that I listed are native to Ontario, and probably many others are as well.
Jeanine Gurley

Joined: May 23, 2011
Posts: 1393
Location: Midlands, South Carolina Zone 7b/8a
Bill Mollisons' answer to the concerns about an inherent danger involved in introducing plants not native to an area. He says "I use only native plants; they are native to the earth. I am using indigenous plants; they are indegenous to this part of the Universe". (Pamphlet IX Permaculture Techniques Page 12 by Bill Mollison). He then discusses why he is in favor of genetic diversity.

1. my projects
Donovan Wentworth

Joined: Apr 14, 2012
Posts: 14
Location: Michigan - Zone 6a-5b
If you're interested in genetic diversity, you won't be encouraging the growth of Russian olive in North America. Russian olive has a tendency to form monocultural thickets and push out more diverse plant life. It isn't simply a non-native plant, it's an invasive one.

The factsheet I posted has a large variety of other plants that can fill the role of Russian olive, so there's really no need to cultivate it if you have access to those other plants.

EDIT: Mollison's comment that all plants are "native to the Earth" makes a nice soundbite, but it ignores a lot of what biologists and ecologists know about the nature of evolution and ecosystem integrity.
Leila Rich

Joined: May 24, 2010
Posts: 3999
Location: Wellington, New Zealand. Temperate, coastal, sandy, windy,
Woohoo, this stuff always gets a bit of debate going!
Here's where "It depends" really comes into its own
NZs ecosystem is extremely delicate and really damaged by human activity. Our moderately wet and reasonably warm climate allows all sorts of plants that would go dormant in their native climates to go nuts, all year.
I'm involved in conservation and permaculture: they have rather different attitudes to plant management...
*edit* I've basically quoted myself from last year: the dangers of posting on old threads without reading properly!

Tom Allyn

Joined: Dec 22, 2011
Posts: 17
Location: Maple Valley, WA
ceog Hatfield wrote:Also, from further reading, of the two, the Black Locust (fast growing, nitrogen fixer, rot resistant, high energy fuel) is criticised as very invasive, whereas Catalpa (pretty, but not much use) is mostly harmless.

That's where I draw the line. Non-native is OK if it's otherwise harmless. Invasive is to be avoided. It's an easy enough distinction.

Here in the Great Northwet we've had a terrible time with invasive Japanese Knotweed. It's decimating some of our local salmon runs. It's got to go, at least along our rivers. We're slowly getting rid of it. Salmon numbers are climbing again. But it's much simpler to simply not introduce the invasive in the first place.

If you have use for a non-invasive non-native then go ahead and plant it. But to knowingly plant an invasive is irresponsible. I wish more landscapers and nurseries understood this.
Kari Gunnlaugsson

Joined: Jun 22, 2011
Posts: 308
The thread 'growing kudzu' covers this ground pretty pun intended and apologies to those of you overgrown with kudzu
growing kudzu

please be responsible

the original poster mentions 100 year events (introductions) and 300 year adaptations...i think most biologists would agree these numbers are out by several orders of magnitude

yes, climate change is going to be a great driver of mass extinction...there is some hope to reduce that impact by having the most resilient systems possible in place so there is a lot of genetic variation to draw from so something comes through..this isn't going to be achieved by introducing exotic invasives that overwhelm native flora and fauna and create biodiversity deserts /monocultures to start with

sure, maybe you'll create tremendous biodiversity in your backyard where you can intensively manage things, but if in the process you convert thousand of acres of wildland (that isn't feasible to manage and needs to be self-regulating) into some monoculture thicket then there is a huge net loss in diversity

i don't think the question 'what did you have for breakfast' is really that relevant, we're not talking about tomato plants..i think the distinction between exotic and invasive is pretty easily made with species that have been around for a few decades...anything brand new should be treated with extreme caution and monitored closely and might not be worth the risk

Kris Minto

Joined: Sep 17, 2012
Posts: 136
Location: Ottawa, Canada -- Zone 4b/5a
I may opinion each person has to define what the word invasive means to them. Just a simple search online will show you a million of different interpretation and definition of the word. I think once you have define what the word is, you can then move forward picking out plant and tree which fits your definition.

Many say mint is invasive but I would believe most of those have smaller yards but someone who has a a large forest garden like Robert Hart and Martin Crawford would likely argue other wise because of the other element around to keep it at bay.

Just my two cents,
James Colbert

Joined: Jan 02, 2012
Posts: 255
I have been thinking about this topic quite a lot lately. Let's take Kudzu for example, it is probably the most invasive of the invasive at least in the US. I have heard from a couple people that kudzu does not grow in thick dense forests. You find kudzu at the edge of a forest or in open pasture. to me this says that well developed and healthy ecosystems don't have problems with invasive species. It would seem that instead we as humans have manipulated the a natural ecosystem in some negative way, for example planting a monoculture of pines and calling it reforestation, and then when something like kudzu comes along and takes advantage of our poor ecological planning we blame the plant and say that it is the problem.

Let us consider a few other things: when a piece of land is properly grazed (no more than 30% of the vegetation is consumed) plant diversity increases. The removal of some plants allows others to thrive. So this is what I would do if I had kudzu land. I would graze, sheep, goats pigs, etc in a sustainable and healthy way then introduce a diverse polyculture which would cover the ground surface preventing unwanted seed germination. It may require some intensive work to remove some of the kudzu mechanically. But the goal should be to find a balance with the plant not eradicate it. In Japan you see a little green plant on the side of the road, ask what it is and you will find out it is kudzu but it is not taking over, it is not crawling up trees and killing them. It is in balance with the surrounding system. That is what will solve the problem (imo) balance not kudzu genocide.
Leila Rich

Joined: May 24, 2010
Posts: 3999
Location: Wellington, New Zealand. Temperate, coastal, sandy, windy,
James Colbert wrote:IIn Japan you see a little green plant on the side of the road, ask what it is and you will find out it is kudzu but it is not taking over, it is not crawling up trees and killing them. It is in balance with the surrounding system.

Japan generally has very cold winters that stop most plants growing for months.
Most of the species that are going nuts here come from environments where cold would control their spread.
Tom Allyn

Joined: Dec 22, 2011
Posts: 17
Location: Maple Valley, WA
James Colbert wrote:I have heard from a couple people that kudzu does not grow in thick dense forests. You find kudzu at the edge of a forest or in open pasture. to me this says that well developed and healthy ecosystems don't have problems with invasive species.

That's a little too broad of statement for me. Some invasives absolutely will take over an otherwise healthy and undisturbed ecosystem.
Rose Pinder

Joined: Nov 18, 2011
Posts: 388
Location: Otago, New Zealand
I agree Tom, and it really depends on the specific plant and location. Also, not all human manage ecosystems are going to be forests.

Going back to the original post, who said that the ideal is native only? I understand that people doing native ecosystem restoration would say that (and in many but not all cases be correct), but it's not a permaculture value.

Personally I find the whole 'native only' vs 'we can plant what we want, it's all natural' dichotomy to be a false one. Native systems will be destroyed if not protected (where I live at least) and that would be a shame. And we have to eat, but that doesn't mean a free for all either.
greg patrick

Joined: Mar 17, 2012
Posts: 168
Location: SoCal, USDA Zone 10b
Personally I like to have a mix of natives and invasives. You'll know you have enough natives when migrating birds spend a few weeks in your trees and ponds, and when you have plentiful pollinators and predators living in your food forest. Personally I use natives for large anchor trees and as wildflowers with very few in between the two extremes. The main natives I have are my nitrogen fixings Palo Verde's, Sycamores and pines. We also have native frogs and lizards, etc.

'Science is the father of knowledge, but opinion breeds ignorance.' - Hippocrates
subject: Invasive planting vs human contribution to evolution.