An invasive species is characterized as a plant, animal, or fungi that has not inhabited a particular area in the recent past (perhaps since the last ice age) and quickly colonizes that ecosystem, often to its detriment. The last part of our definition is the most subjective.
Cane sugar is native to south Asia, but we cultivate it all over the world. In the 1930s, grey-backed cane beetles were eating Australia's sugar crop. Poisonous cane toads were introduced to Australia in 1935, to eat the beetles. The toads never ate the beetles, and the toad population soared (link to video). Nothing eats the toads, because they are poisonous. Everyone hates them, and as a result, they are considered "invasive."
Autumn olive, elaeagnus umbellata, is native to northeast Asia and the himalayas. It is a nitrogen-fixing shrub that spread quickly and has edible berries. It quickly colonizes abandoned pastures, stone walls, and hedgerows. Many naturalists, conservationists, and nativists in the United States prefer species that are indigenous to North America. They strongly dislike autumn olive, because it spreads quickly and is not native. They consider it to be "invasive," because they dislike it.
Are you familiar with any other species that are spread by wildlife and quickly colonize abandoned pastures? Buckthorn is a good example: the thorny shrub and its poisonous berries don't do us any good. Everyone hates buckthorn. How about wild apples? The large, juicy fruit is attractive to animals: they eat it and subsequently disperse its seeds.
We, humans, are animals. We like apples (along with many other food crops), and disperse their seeds for our benefit. Personally, I don't consider refined cane sugar to be a food: in our bodies, it behaves much more like a drug. In Australia in the 1930's, we replaced the native ecosystem with drug cultivation. When the ecology rejected our crop, we ignorantly introduced the cane toad, which we now consider to be invasive.
Let us ask a follow-up question: which invasive species preceded the cane toad?
The sugar perhaps? Sugar doesn't spread on it's own.
Well, then who planted the sugar?
Consequently, are humans invasive?
So autumn olive is invasive, you say? According to whom? Have these conservationists eaten the shrub's berries? Do they put cane sugar in their coffee? If so, where was that sugar grown? What ecology did that sugar replace?
I don't mean to be overly confrontational, but we must take a look in the mirror before categorizing useful food-bearing shrubs as invasive.
Autumn olive is also known as "autumn berry," because that sounds much nicer. The shrubs produce copious amounts of fruit that I enjoy eating raw (and I don't go around eating super-astringent wild foods just to be hip). Autumn berry is also fantastic in jam and syrups. The fruit easily falls from the tree with a light shake, and can be collected in large quantities on a tarp.
Jeremy and I recently visited Mastodon Valley Farm, in Viola, Wisconsin. Maureen (Mo) and Peter Allen graze 300 acres of pasture and silvopasture with cattle, goats, pigs, and sheep. They live happily in a humble, but beautiful cabin (that you can read about on their blog), and raise their 1.5-year-old daughter, Tilia, in sync with the rhythms of the earth. They respect and enhance their ecosystem, and are true stewards of the land. Peter told us that Mo had taken Tilia up to one of the pastures to pick and eat autumn berry. They had a lovely afternoon, and Tilia learned to identify the autumn berry shrubs, even those that had no fruit on them.
In conclusion, what should we consider to be "invasive?" In would seem as though "invasive" is an opinion. To when is a species native? What are your thoughts? Feel free to leave a comment on our facebook page. Over and out.
I'm busy working on my blog posts. Watch this space!