WHO would have thought it: the winner of the most pointless waste of time award for 2018 isn’t the Department for Exiting the EU, it’s the National Trust for Scotland for planning to send people into a gorge to destroy so-called non-native species. In the trust’s own words, it is taking the action in Corrieshalloch Gorge in Wester Ross to defend “local” plants and repel “aggressive” invaders. But when exactly did we start talking this way about foreign species coming over here and taking our trees and shrubs? When did we get so UKIP over plants?

Obviously, the operation at Corrieshalloch is not going to be easy. For a start, the gorge is 200ft deep which means the only way to get at the “non-native” species – Japanese knotweed and rhododendron ponticum – is to abseil down. The abseilers then have to identify where the plants are and spray them with weed-killer. Even the trust admits it’s pretty extreme stuff, but this is the point we’re at now. In fact, the people working to eradicate “non-native” species see operations such as the one at Corrieshalloch as a “war” or “battle” against an “invasion” or “swarm”. Those are the words they use. The defenders of our apparently native plants talk like they’re on a battlefield or in a B-movie. And no-one laughs.

However, I think now is the time to start questioning the orthodoxy, if only to save us from more hyperbole. The narrative of the National Trust, and other organisations – backed by the Scottish and UK Governments – is that “non-native” species cost millions of pounds and that they must be eradicated to protect the “native” ones, even though their argument defies common sense, the history of the planet and the evolution of plants and animals. A fir tree or a grey squirrel doesn’t know where the border between two countries is, and nor should they, because the division between native and non-native, like borders, is entirely man-made.

The rhododendron ponticum that the National Trust wants to eradicate from Corrieshalloch is a good example. The plant has had all kinds of UKIP-style rhetoric thrown at it over the years (it’s even been called “evil”) and it’s mainly because, according to its detractors, it spreads fast and prevents other plants from growing. James Fenton, an ecologist who has worked for the National Trust, has even suggested that if we took no action to control the plant and came back in a thousand years, the landscape of Scotland would be just one dark rhododendron forest.

But could I stick up for the rhododendron ponticum, based on what the plant actually does? It’s true that it thrives in certain types of soil, but it is no more or less likely to spread than ivy or bracken. The difference, of course, between bracken and rhododendron ponticum is that one is considered native and the other non-native even though rhododendron ponticum was certainly in this part of the world before the last Ice Age and was then reintroduced to Britain from seeds 200 years ago. How long does a plant have to be here before it is considered native?

The idea that rhododendron ponticum would spread ad infinitum is also flawed – that’s just not how nature works. For example, the Americans used to get hysterical about the purple loosestrife plant, which was accused of the same crime as rhododendron ponticum – reducing diversity – but the long-term evidence was different: there was a first wave of the plant, then it declined, and the natural diversity reasserted itself. With the exception of very small islands, this is what new species in an area do: they increase diversity rather than reduce it.

The search for a scientific definition of “non-native” does not help either because there isn’t one. In fact, the whole idea of native and non-native was pretty much invented by Victorian botanists like Hewitt Watson, although no one has ever really been able to agree what the words mean. Should we go back to some kind of year zero –but then how far back would you go? And if you go too far back, you reach a point where the world was one great continent anyway and every plant and animal could spread and roam freely.

Some attempts to define native and non-native are based on whether there has been human intervention, which is the Scottish Government’s approach, but this is also far from consistent. There is a widely-held view, for example, that grey squirrels (which were introduced by humans to Britain 120 years ago) are non-native and should be culled, but why aren’t we seeking to eradicate other species that have been introduced such as the common pheasant? And what about the collared dove? Why spend money on measures to control the grey squirrel (which are never going to work anyway) and nothing on the collared dove, which has only been around in the UK since the 1950s but is presumably competing with “native” birds for food?

It is this kind of inconsistency that makes a mockery of the whole native/non-native division and the National Trust for Scotland’s operation at Corrieshalloch Gorge. Let’s deal with facts instead. Such as this one: plants and animals are not harmful just because they were introduced by humans, nor are they necessarily good for biodiversity because they weren’t.

And this fact: there are much greater environmental threats than the spread of “non-native” species, such as plastic and other types of waste, intensive farming, and industrial pollution - all of which are linked to the most dangerous native of all: humans.

And then there’s this fact: our ecology is changing all the time, animals and plants come and go, they thrive, fade, spread, fall back and rise again, and there’s no reason why a diverse and healthy environment of the future can’t include so-called non-native species. In fact, do you think that in a thousand years the petty definitions that are driving us to the bottom of gorges with weedkiller will matter? Our ecology will have moved on. There may not even be a Scotland or any other border by which to define our species. And the best thing about that? The plants and the animals will just get on with it anyway. They won’t even notice.