Ok but can we talk about non-native and invasive species in a nuanced way?
There’s more to this topic than ‘native = good’ and ‘non-native = invasive and therefore bad’. I also see horrible analogies with human immigration, which…no. Just no.
Let’s sit back and learn about species and how they work inside and outside their native ranges! Presented by: someone who studied ecology.
Broadly speaking, when talking about species in an ecosystem, we can divide them into four categories: native non-invasive, non-native, non-native invasive, and native invasive.
Because ‘native’ and ‘invasive’ are two different things.
Native and non-native refers to the natural range of a species: where it is found without human intervention. Is it there on its own, or did it arrive in a place because of human activity?
Non-invasive and invasive refers to how it interacts with its ecosystem. A non-invasive species slots in nicely. It has its niche, it is able to survive and thrive, and its presence does not threaten the ecosystem as a whole. An invasive species, on the other hand, survives, thrives, and threatens the balance of an ecosystem.
Let’s have some examples! (mostly featuring North America, because that’s the region I’m most familiar with)
Native Non-invasive
Native bees! Bee species (may be social or solitary) that pollinate plants.
And stopping here bc I think we get the point.
Non-native
Common Dandelion: Introduced from Europe. Considered an agricultural weed, but does no harm to the North American ecosystem. Used as a food source by many insects and animals. Is prolific, but does not force other species out.
European Honeybee: Introduced from Eurasia. Massively important insect for agricultural pollination. Can compete with native pollinators but does not usually out compete them.
Non-native Invasive
Emerald Ash Borer: Beetle introduced from Asia. In places where it is non-native, it is incredibly destructive to ash trees (in its native range, predators and resistant trees keep it in check). It threatens North America’s entire ash population.
Hydrilla: An Old World aquatic plant introduced to North America. Aggressively displaces native plant species, and can interfere with fish spawning areas and bird feeding areas.
Native Invasive
White Tailed Deer: Local extinction of the deer’s predators caused a massive population boom. Overgrazing by large deer populations has significantly changed the landscape, preventing forests from maturing and altering the species composition of an area. Regulated hunting keeps deer populations managed.
Sea Urchins: The fur trade nearly wiped out the sea otters that eat them. Without sea otters to keep urchin populations in check, sea urchins overgrazed on kelp forests, leading to the destruction and loss of kelp and habitat. Sea otter conservation has helped control urchin populations, and keeps the kelp forest habitat healthy.
—
There are a few common threads here:
The first is that human activities wind up causing most ecosystem damage. We introduce species. We disrupt food chains. We try to force human moral values onto ecosystems and species. And when we make a mistake, it’s up to us to mitigate or reverse the damage.
The second is that human moral values really cannot be applied to ecosystems. There are no ‘good’ or ‘bad’ species. Every species has its place. Applying emotional and moral rhetoric to ecology works against our understanding of how our ecosystems work.
Third: the topic of invasive and non-native species is more complex than most of the dialogue surrounding it. Let’s elevate our discussions.
Fourth: If you ever compare immigrants or minorities to invasive species, I will end you.
There are more nuances to this topic than I presented as well! This is not meant to be a deep dive, but a primer.
THE OLD FRIENDSHIP OF BLUEBERRIES AND SWEET FERN:
"In the time before refrigeration, Ojibwe folks kept their blueberry harvest fresh by lining their birchbark storage containers with a plant called sweet fern that often grows right alongside blueberry bushes!
The leaves of sweet fern produce a compound called gallic acid, which is a potent anti-microbial and keeps harmful bacteria like salmonella from growing on the berries.
It's name in the Ojibwe dialect I've learned is "giba`iganiminzh" meaning "it covers the berries" because of this usage and its contribution to keeping the precious staple food of minan (blueberries) fresh!
I don't use a birchbark container but I do pop a few sprigs of sweet fern into my gathering bag when out picking and then into my tupperware when storing berries to remember and utilize the gifts of this wonderful plant!
(Sweet fern can also be used as a medicinal tea to help the intestines and colon! And when added to a fire, the smoke will help keep away mosquitos and horse flies--in addition to smelling lovely!)" - The Native Nations Museum, founded by Chippewa Bonnie Jones
Some of you may have heard about Monarch butterflies being added to the Threatened species list in the US and be planning to immediately rush out in spring and buy all the milkweed you can manage to do your part and help the species.
And that's fantastic!! Starting a pollinator garden and/or encouraging people and businesses around you to do the same is an excellent way to help not just Monarchs but many other threatened and at-risk pollinator species!
However.
Please please PLEASE do not obtain Tropical Milkweed for this purpose!
Tropical milkweed (Asclepias curassavica)--also commonly known as bloodflower, Mexican butterflyweed, and scarlet milkweed--will likely be the first species of milkweed you find for sale at most nurseries. It'll be fairly cheap, too, and it grows and propagates so easily you'll just want to grab it! But do not do that!
Tropical milkweed can cause a host of issues that can ultimately harm the butterflies you're trying to help, such as--
Harboring a protozoan parasite called OE (which has been linked to lower migration success, reductions in body mass, lifespan, mating success, and flight ability) for long periods of time
Remaining alive for longer periods, encouraging breeding during migration time/overwintering time as well as keeping monarchs in an area until a hard freeze wherein which they die
Actually becoming toxic to monarch caterpillars when exposed to warmer temperatures associated with climate change
However--do not be discouraged!! There are over 100 species of milkweed native to the United States, and plenty of resources on which are native to your state specifically! From there, you can find the nurseries dedicated to selling native milkweeds, or buy/trade for/collect seeds to grow them yourself!!
The world of native milkweeds is vast and enchanting, and I'm sure you'll soon find a favorite species native to your area that suits your growing space! There's tons of amazing options--whether you choose the beautiful pink vanilla-smelling swamp milkweed, the sophisticated redring milkweed, the elusive purple milkweed, the alluring green antelopehorn milkweed, or the charming heartleaf milkweed, or even something I didn't list!
And there's tons of resources and lots of people willing to help you on your native milkweed journey! Like me! Feel free to shoot me an ask if you have any questions!
Just. PLEASE. Leave the tropical milkweed alone. Stay away.
TLDR: Start a pollinator garden to help the monarchs! Just don't plant tropical milkweed. There's hundreds of other milkweeds to grow instead!
This may look like a moss, but it isnt! This is a broad-leafed plant in the carrot family, Apiaceae.
These plants can grow to bve over 3000 years old. This large specimen may be over 1000 years old.
photographs by Mark Dwyer
icon: Cressida Campbell"I know the human being and fish can co-exist peacefully."
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