Tag Archives: alien

Mark Davis: Rethinking Invasive Biology

Mark Davis' 2011 paper "Don't Judge Species on their Origins" was not well-received by sections of the ecological community. But why is a call for rethinking our attitudes to invasive species so controversial?

In the series Norway’s Newcomers, we’ve looked extensively at not only Norway’s non-native species, but the genetics, definition and even the defense of alien species. So it made sense that we’d eventually find our way to interviewing an invasion biologist. I was in St. Paul, Minnesota earlier this year and was lucky enough to sit down with Professor Mark Davis.

Mark has been a strong opponent of the demonisation of invasive species for decades. Whilst many ecologists’ first reaction is to eradicate any non-native species, Mark has urged caution, and encouraged the community towards less pejorative terms. I spoke with Mark about the impact our work has on public opinion, how we should talk about non-natives, and living with the impact of invasive species going forward.

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Making Lake Superior Again: Thoughts from the International Charr Symposium

Lake Superior, the location of the 9th International Charr Symposium

Lake Superior, the location of the 9th International Charr Symposium (Image Credit: Wikipedia Commons)

This week I’ve been lucky enough to represent NTNU at the 9th International Charr Symposium in Duluth, Minnesota, a conference focussing on one of my focal species in the genus Salvelinus. Conferences are like this are great for soaking in a swathe of alternative perspectives, so I thought I’d share a few thoughts from day one of the symposium, including a sign of success, one of innovation, and another of hope.

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In Defense of Aliens

It's important to remember that not all alien species are harmful, and we shouldn't treat them all as such

Building on last week’s article on defining invasive and alien species as well as the work of Professor Mark Davis, I am going to do the unimaginable for an ecologist and argue that maybe alien species aren’t always a bad thing. I want to emphasize that maintaining biodiversity is essential, but maybe we should focus on the role of species in their environment rather than their place of origin.

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The Sitka Spruce

The Sitka Spruce was introduced by the timber industry, and now covers almost 5 million hectares in Norway

Guest post by Tanja Petersen

Once again, let us talk about trees. Do not be fooled by their innocent appearance – that is exactly what they want! In reality, they can be just as problematic as any animal species. This week I takes a closer look at the Sitka spruce (Picea sitchensis).

Where did it come from?

It originates along the west coast of North America, and it was first introduced to Europe for timber production – the main route for invasive tree species. The first recorded appearances in Norway are from around 1890. In Canada and Alaska the distribution of Sitka spruce overlaps that of the White spruce (Picea glauca), producing the (fertile) hybrid Picea × lutzii, which has also been introduced in Norway. In Norwegian nature institute Artsdatabanken’s new assessment of alien species, this new hybrid and the Sitka spruce have been combined as one species, as plantations of what was assumed to be one, turned out to be the other, and vice versa. To make matters worse, the hybrid is capable of back-reproducing with both parent species. A family tree that would make even the Lannisters from Game of Thrones frown!

If you want to tell the Sitka spruce apart from other spruce species, the most characteristic traits are flat needles, which are green on the topside, and a whitish blue underside – and that the needles are extraordinarily pointy! A characteristic that has earned the species quite a few uncharismatic nicknames in Danish: the “hedgehog spruce”, “stabbing spruce”, and my personal favorite: the “shit-that-really-hurts spruce” (these were some more-or-less creative translations from the Danish Environmental Protection Agency’s fact sheet).

Where did it go?

The Sitka spruce is the most commonly introduced tree in Atlantic Europe, having reached even as remote areas as Iceland. In Norway, the area covered by planted Sitka spruce is estimated to be around 50 km2. At the same time, it is present in most of the country – the most likely estimated area of occurrence is 48,000 km! It was introduced here due to its high wind- and salt tolerance – which is definitely something you want in a tree destined for production in coastal Norway!

The Spruce's needles have earned it many creative nicknames, many involving cursing

The Spruce’s needles have earned it many creative nicknames, many involving cursing (Image Credit: brewbooks, CC BY-SA 2.0)

What does it do here?

So why is it a problem? One more conifer species in Norway does not seem like a bit issue at first glance, does it? Well, just as in the human world, things are not always merry when you bring in an extra relative. The Sitka spruce can cause problems when it starts moving outside of its intended plantations (just as when your small cousins etc. move outside of the designated “play-area”).

It matures quite early, occasionally producing cones already at 6 years old – almost a teenage pregnancy in the conifer world. Luckily, most Sitkas are more responsible, and wait with reproduction until they reach 20-40 years. It produces more seeds than other spruce species – so both early and massive reproduction. Traits definitely desirable in timber, not so desirable in a potential invader. These factors together is what makes it a potential problem: simulations from Artsdatabanken gives Sitka spruce a potential range expansion speed of 600 m/year – that may not sound fast to animals like us, but it’s borderline Usain Bolt speed for a tree!

However, as you probably know by now, it is not just the ability to move fast and far that makes a species invasive – it should also have a negative effect. In this case, it has an annoying tendency to move into nature types which are on the Norwegian Redlist. Here, it outcompetes the native vegetation by “stealing the spotlight” – and doing it very quickly. And if there is one thing we can’t stand, it is an obnoxious, bratty little cousin who steals the seat of a beloved grandmother, to complete the family metaphor.

So can’t we just… cut it down?

So we’ve established that the spruce is reducing biodiversity in Norway, and that it’s spreading quickly. But it’s a tree, right? What’s the issue? Get some of those deforesters up here STAT! But the spruce is a favourite among foresters and timber merchants in Norway. This is a case of economic priorities coming first, at least for the moment. And as long as the spruce benefits the timber industry, there’s the constant threat of it being able to escape from planted areas and wreak havoc.

For more information on the spruce, we invite you to read the following studies.

The Sikta Spruce – Artsdatabanken profile (Norwegian only)


Defining an Invader

With the rebranding of Nrwaoys' Black List as the Alien Species List, we look at what makes a species alien and/or invasive (Pictured: The invasive Yellow Sweet Clover)

Two weeks ago, Norwegian Science Institute Artsdatabanken (ADB) announced that they would be changing the name of their invasive and alien species index. Formerly known as the Black List, the institute decided to use a name with less negative connotations, “Fremmedartslista“, loosely translated, the Alien Species list. Given this series’ focus on species from that list, it seems like an appropriate time to look at how we define the terms ‘alien’ or ‘invasive’ species.

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Alien Trees & Filling the Knowledge Gap

Guest post by Tanja Petersen

recent report jointly published by WWF, Sabima, Friends of the Earth Norway and the Norwegian Botanical Society showed that alien tree species are one of the largest threats to native tree species, even inside protected areas. The news even reached Norwegian news outlet NRK. But why are alien trees a problem? Isn’t a tree, well, just a tree? As guest blogger Tanja Petersen explains, not quite.

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Invaders in the Garden

The Japanese Knotweed, an invasive species often found in gardens (Image Credit: Max Pixel, CC0 Creative Commons)

Guest post by Malene Nygård

Garden plants have a long tradition in Norway; from being used as medicine and food in the gardens of Catholic monasteries in the Middle Ages to today’s exotic ornamental plants. But this tradition also represents several centuries of unmonitored introductions of alien species, and it has left its mark in Norwegian nature.

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