Most ecosystems in the world today, have to deal with invasive species disturbing the natural balance of the system. Foreign plant species often get introduced through gardeners trying out something new in the garden, then losing control of what they planted. Some species, such as red oak and non-native honeybees, were introduced for commercial purposes. In some instances this was done because there was a real benefit to be had from the non-native species, other times this benefit turned out to just be imagined (as is the case in honeybees).
What makes invasive species so successful? Well, firstly we only name something an ‘invasive species’ when it becomes a pest in the landscape. So, anything that can’t deal with our winters or has a natural predator present to keep the population down, will not really be seen as an invasive species. We will use the term ‘exotic plant/species when a species occurs outside its natural habitat but doesn’t push away natives or causes no harm to humans or native animals.
Invasive or just non-native?
Most of what we plant as food crops or keep as livestock will fall under the ‘exotic/introduced species’ category. Should you feel guilty for having them? In most cases the answer to that is a resounding ‘no’! Food crops especially, have the built-in safeguard that they’re tasty. Both humans and animals instinctively realize this and keep the population in check by eating the plant. But you should be careful not to lose control of the plants and animals you keep. Also, before you introduce a plant to your garden, do some research. Is it already invasive? Or is it causing trouble in other countries? If the answer to one of these questions is ‘yes’, you may want to reconsider.
Some well-known invaders
In the Dutch/Flemish lowlands, we have lots of issues with turtles (Trachemys scripta, red-eared terrapin). These turtles first came into our countries as pets, but many people who got sick of them simply let them loose in the wild. They can grow to an impressive size, have no natural enemies here and can protect themselves from the cold in winter.
If you are reading this and you’re from an area where these guys are natives, could you please help us out over here and post a recipe and a good method for catching them? They’re really wreaking havoc.
Another example of an invasive species in western Europe is the northern red oak or champion oak (Quercus Rubra). Why is it invasive? Well, compared to our own European oak (Quercus robur), the champion oak has foliage that composts very slowly, it forms a very dense groundcover around the tree. This covering makes it difficult for other species to germinate, especially because like most oaks, tannin from digested leaves makes the soil less hospitable to other species. Acorns are less attractive to native forest creatures that would normally feast on them, instead they prefer acorns from the native trees. I think it’s safe to assume the scenario would be reversed in the USA where this tree is native. The red oak grows faster than European oak and because of this, has been planted on a large scale as trees to be harvested.
Despite the red oak reducing biodiversity, it is an incredibly stunning tree during fall.
As a beekeeper I know I shouldn’t be too unhappy with the third one, but I just hate this stuff. Himalayan Balsam is very common on the sides of ditches and rivers. Its spread is helped by the river current and it covers large areas. When it’s in bloom, it will be enthusiastically visited by pollinators and will give off a very strange smell. The smell of an old, shady pond. Because it spread so strongly and covers so much ground, biodiversity on riverbanks is reduced drastically.
Some people with large backyards are worried about the amount of possible Lyme-carrying ticks waiting to pounce upon animals or humans. Wisely, we look for non-harmful ways to control the tick population such as letting Guinea fowl run around the garden. American homesteaders have a lot more reasons to be worried about ticks, because a higher percentage of ticks carry Lyme. Because of this the Guinea fowl solution is more well-known there. Well-known homesteader, Justin Rhodes, has Lyme disease and uses Guinea fowl to reduce the number of ticks on his homestead.
But Guinea fowl are native to Africa, not Europe and not North-America! It’s a non-native species, but not an invasive one, because it has plenty of natural predators and is a useful addition to our ecosystems.
Personally, I gladly use runner ducks in the garden to help me combat slugs. There is no danger of these Indonesian ducks becoming an invasive species, since they fall prey to foxes, martens, hawks, buzzards and many others! They also don’t breed quick enough to out-compete native species.
Some species that are by definition exotic, get ‘naturalized’ over time, meaning we consider it as native. In Flanders this can be said about Robinia Pseudoacacia. Originally, this tree came from the south-east of the United States, where it’s known as Black Locust. One of the reasons for this tree getting naturalized is the length of time it has been present in Europe. In Britain it was introduced in 1636, and it was spread further into Europe from then on. It also doesn’t really push native trees out. Black Locust doesn’t do well in places where the soil is very moist and is acidic. These difficulties function in a similar way a predator does to animal populations.
Black Locust grows quickly, produces good-quality wood that can rival tropical hardwoods in durability. From a beekeepers’ perspective, the Black Locust is a treasure. It grows a huge amount of flowers which are incredibly valuable to bees. In a country where habitat for pollinators is under incredible pressure, the Black Locust is very welcome.
If I need to make a conclusion about the issue of invasive and non-native species, it’s this; every ecosystem is unique in ways we can’t always understand. It is dangerous to introduce or take away species when we don’t fully know all the functions they perform. If we do recklessly introduce a new species, there is a chance we’ll be sorry in the years to come. By that time this species might be causing a massive problem.
There are cases where a newcomer provides benefits to the ecosystem, in which case, great! But this benefit cannot outweigh the importance of biodiversity and the various functions fulfilled by native species working together. There is certainly much more to be said about this subject, every species or category of beings is deserving of attention. As a beekeeper, I am most interested in honeybees and their habitat. If the European black bee interests you, be sure to follow this blog so you don’t miss the follow-up.