Introduced species success stories and 'good' non-native species

Nature Talk
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There’s invasive species, naturalized, non-invasive, right? So any species that’s on an invasive species list for an area is already a no go.

Naturalized, like, arguably stuff like dandelion is, and its not causing issues (outside of a few areas) because all it really does is grow in turf grass or disturbed flower beds.

So that leaves stuff that isn’t invasive and doesn’t naturalise itsself - I feel like this is the area of plants that I feel like its generally the things that are going to be okay to plant even if they’re not native, but they don’t really get talked about (outside, ooh, that’s pretty, when you’re at a garden center,) because they’re just… not causing issues. An example that comes to mind are the various hybrid barrenwort species you can find for sale at garden centers; I have a few myself, they’re nice for the shade and I don’t think I ever even see them pollinated.

Or columbine hybrids - sure the hybrids will drop seeds and root but they’re not really vigourous enough to crowd other things out, and the (also not native) columbine sawflies will do a great job of keeping them check in the spring while for some reason leaving our native Aquilegia canadensis alone.

I’d consider a pretty garden plant that doesn’t really get aggressive and might actually get your typical midwestern homeowner to plant something besides boxwoods and hostas a bonus.

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Noxious is generally the term used by government agencies for “no go” plants Noxious Weed Species ID | Department of Agriculture (colorado.gov)

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Ah, good correction. Thanks!

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I’ve seen them extensively up to 12,000 feet and above in the Kenosha Mountains SW of Denver, where there is little human disturbance.

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In Colorado, Great Mullein here will take over an area, most definitely. A lot of my weeding in State Parks over the last 15 years has been dense stands of mullein. Birds do go after the seeds - and help spread them, I’m sure.

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There are native dandelions too

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I’d encourage you to think about what you mean by beneficial. Introduced species being beneficial to humans? There are certainly many examples of that, including most crops and livestock.

Beneficial to other species or the wider ecosystem? How do you define that? Most ecological changes, including species introductions, will benefit something, but clearly, introduced species are not needed for ecosystem functioning, so it’s a case of looking for superfluous benefits, while there can be real harms.

Most introduced species don’t thrive to the level of becoming invasive and causing harm, but this is no reason to be complacent about allowing them to colonise. The problem is that we don’t know in advance which species will cause problems. The conservationist Peter Scott, who founded the WWF and the Wetlands Trust, introduced the Ruddy Duck to Europe, and despite his deep knowledge of wildfowl and ecosystems, made explicit statements at the time that he didn’t see how this would ever cause any problems. Now this introduced species is described by BirdLife International as the “greatest long-term threat” to the survival of the Endangered White-headed Duck.

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Introduced biocontrol species can be good when they don’t go really bad. I think the introduction of Diorhabda beetles to fight Tamarix invasions in North America was a good thing but we will see.

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Mullein is highly invasive in subalpine areas of Hawaii as well. Not as bad as other things like gorse or Madagascar fireweed – it’s usually at relatively low density – but not great, it can spread extensively and probably sucks up a lot of water in these kind of semi-desert landscapes.

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The difference is that in the latter case, other natives are usually adapted to succeed or compete with it, and there are usually some kind of natural enemies present. For example, in New Zealand manuka is a valuable early successional species that colonizes disturbed areas, keeps out non-native invasives, and then after 20 years or so gets replaced by a more diverse set of native plants. In Hawaii, manuka can establish itself in undisturbed scrub forest, and the toxic leaf litter keep out not only other non-native plants but Hawaiian natives, leading to a perpetual monoculture.

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Logically, every species originated evolutionarily as a narrow endemic in one place of origin. So every non-endemic went through an “invasive” stage as it had to outcompete prior occupants of its present-day range.

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Lots of examples spring to mind, and lots of Q’s

What do you mean by ‘native’.

We’re planting trees from the other end of Australia to compensate for lost flowering time so we can keep nectar feeders alive. Politically they’re native, same country. But if it were Europe, they’d be five countries away.

And we’re bringing trees from a few hundred km north to allow for global warming.

Dingos, been here for 5,000 years - native? We (ecologists) like dingos - they reduce cats, foxes, overabundant roos. And sheep, so farmers don’t like them.

Rodents, only been here 20 million years. Are they natives yet?

https://nre.tas.gov.au/invasive-species/invasive-animals/invasive-birds/rainbow-lorikeet

dung beetles - self limiting when there’s no dung, cleaning up a mess that we made 1) the european invasion C200 years, and the megafaunal extinctions C40,000 years.

dinofelis “Is the dandelion really taking over and displacing natives, or just filling in after human disturbance displaces the native plants?” Thanks. I have the same conversation re: Mistletoes ‘killing’ Eucalypts along roadside verges after all the others have been chopped down.

deboas “I’d encourage you to think about what you mean by beneficial. Introduced species being beneficial to humans? There are certainly many examples of that, including most crops and livestock.” Thanks for that thought.

jasonhernandez74 “Logically, every species originated evolutionarily as a narrow endemic in one place of origin. So every non-endemic went through an “invasive” stage as it had to outcompete prior occupants of its present-day range.” And you should have seen when South America and North America collided a few million years ago.

I wonder how we view those perhaps rare natural invasions, ie not anthropogenic, the apocryphal lizard floating on a log, or a bird blown off course. Flying foxes only arrived in Adelaide C20 years ago. It could be argued that they were facilitated by fruit trees, farms etc. Or that they weren’t.

Great topic, thanks.

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I focus on plants. I plant to promote insects for their ecological value. Echinacea, the common sunflower, and Gaillardia are not native to the Delaware Valley, but they’re still valuable for bees, wasps, and goldfinches in the valley while not displacing the “true” native species. The same thing goes for garden hybrids. Some can bring surprising wildlife benefits (though they don’t usually support as much as a wild type). Eastern red cedar, a plant native to the eastern US, has become invasive due to wildfire suppression. It’s not always obvious. Ecological interaction is what determines an invasive species. Invasive species destroy resources relied on by endemic species. Butterfly bush is a great example. Sure it feeds adult butterflies, but caterpillars grow on plants found in habitats that butterfly bush takes over. I’ve read a few of Doug Tallamy’s books. I think he’d be way better at explaining this than me.

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a lot of what causes invasive species to spread so widely and rapidly is the extensive human disturbance that exists now, so when that was at a much lower level, new introductions were probably not nearly as likely to spread as explosively as they do now. They were also much rarer.

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This is a good point, perhaps its because in the colonial age people didn’t really care overly much about the environment, only what makes it more comfortable to survive and thrive in a new country.

Good point, it is an important distinction to make. Personally I only consider something native if it already has its own ecological niche in the area in question, and other species have adapted to their existance, for example invasives such as cane toads are actively outcompeting other frogs, and areas have no balance in the ecosystem when they are present- Dingos on the other hand have a niche they occupy, with most natives able to coexist and even benefit from their presence.

The replies have been really informational and good to read, one thing that keeps getting reinforced is the fact that humans love to meddle where they shouldn’t, and mistakes and stuff-ups are much more common than incredible successes, even when it seems to work in the beginning.

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snakesrcool

“Personally I only consider something native if it already has its own ecological niche in the area in question, and other species have adapted to their existance.”

Hmm… Try this on for size.

If something arrived say 10,000 years ago, and wiped out several species, and changed vegetation composition and structure, and learned to live with what was left, then in fact it (now) has its own ecological niche.
“… other species have adapted …” Does that include by becoming extinct? What does ‘adapt’ mean?

This situation could be seen through a different lens.
Once you’ve broken as much as your technology will allow, and can’t break any more, then can you be said to have become native? Can you be said to live in harmony with your (new) environment?

“humans love to meddle where they shouldn’t, and mistakes and stuff-ups are much more common than incredible successes, even when it seems to work in the beginning.”
That works if we assume teleology. But if I were a cane toad, or a cat, or other non-human invasive species, you’d be talking about the same process quite differently.
Either way, move in, break stuff, live in the wreckage.

HTH :-)

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Interesting topic. I have often wondered this as it seems about 90% of the plant species and many other species I see are invasive, and a few are classified as noxious, in my area. However, on many of the plants, such as yellow star thistle and moth mullein, I see native bees and flies foraging. So I don’t exactly know what beneficial and not beneficial mean.

Actually, humans are now probably the most noxious invasive given our population and penchant for development.

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If we have removed the indigenous / native plants they evolved with, insects must either survive on our cosmopolitan weeds, or our commonorgarden must have eye candy, or …

We have specialist oil collecting bees. But plants can be tricksy too, mimicking the colour and bloom time, then cheating on providing nectar.

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It isn’t quite as grim as that. There are extensive native woodlands in Britain, though it is true the majority was cleared centuries ago. The idea that we formerly had coast to coast woodland has been challenged. Given that there were large herbivores present, a mosaic of woodland and grassland seems more likely in the early post-glacial. Woodland would probably have expanded as Mesolithic hunters reduced the herbivores then woodland clearance got going with the rise of Neolithic farming.

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That makes sense.

Are there photos/writeups or iNat observations of a native British woodland that isn’t a plantation? I’d love to see it, i’m very curious