Alien plants

[veronica]

The latest public-participation campaign from Plantlife is looking at invasive alien species.
People are asked to report any sightings of three species- the deceptively inconspicuous New Zealand Pygmyweed, the deceptively pretty Indian Balsam, and the infamous Japanese Knotweed. Just record the species, abundance and location, online or by postcard.
You can also register support for their campaign to ban the sale of recognised invasive alien plants in garden centres.
More details on the Plantlife website.

[nightshade]

I was looking at japanese knotweed at an agricultural training centre only the other day!

[Walwyn]

Adding in the clicks:
http://www.thewildflowersociety.com/...e_invaders.htm
http://www.plantlife.org.uk/PlantInvaders/index.asp

[Airehead]

I shall certainly report a couple of local patches of knotweed. But what can be done about it?

3 years ago on the Scottish west coast estate where I spend most of my holidays a lot of money and effort was poured into trying to get rid of the Rhododendron ponticum. I can't remember which environmental department it was. They cut down great swathes of the stuff through the woodland on very steep and very rugged slopes. According to the estate owner, it was intended to get rid of it permanently. Fat chance! It is now growing healthily again.

[garybaxter]

I was wondering if any1 can help me. A colleague of mine recently attended a pond management course and it was suggested that laying down black plastic over a pond was an effective way of getting rid of parrot's feather I was wondering if anybody has tried this

cheers

[senua]

There is an area near here that has both Japanese knotweed and Indian Balsom. Unfortunatly loads of it.

[veronica]

Interestingly, the BSBI have posted an article (http://www.bsbi.org.uk/html/alien_invaders_.html) by a couple of members disputing the extent to which alien invasions are a cause- rather than a symptom- of ecological problems (in a similar vain to red squirrels v. greys v. forest-degradation arguments).

Nonetheless it seems worthwhile to take part in Plantlife's survey; whether you view the aliens as a destructive force in their own right, or as an indicator of other problems, the data is still useful.

[Imaginos]

Originally Posted by veronica

Interestingly, the BSBI have posted an article (http://www.bsbi.org.uk/html/alien_invaders_.html) by a couple of members disputing the extent to which alien invasions are a cause- rather than a symptom- of ecological problems (in a similar vain to red squirrels v. greys v. forest-degradation arguments).

Nonetheless it seems worthwhile to take part in Plantlife's survey; whether you view the aliens as a destructive force in their own right, or as an indicator of other problems, the data is still useful.

A very good article, I'd like to take issue with the comparison with the invasive native flora (brambles, Ivy etc.) as the native plants will host a wider range of invertebrate species than invasives and therefore the latter are a much greater detriment to biodiversity even if in pure floral terms both alien and native cause (or are affected by) similar problems.

[Airehead]

But does all the discussion and gathering of statistics give rise to any effective action?

I informed the EA a few years ago of giant hogweed on a site from which it was spreading its seed down river. They were at the time asking for info, but they have done nothing. I have just reported, to the site mentioned above, some Jap. knotweed spreading across an isolated situation near my home but I will be very surprised if it is not left to continue spreading. I have mentioned above the failed attempt to eradicate R. ponticum (yes, there was action on this occasion, but misdirected). And so on.

And yet, if I suggest on this site that the most important issue is to make sure that we do not import yet more alien species, e.g. Harris hawks and African snails (yes I know they are not plants but the principal is the same), everyone is quite blase about it. We even have home-grown 'experts' who suggest that our ecology will tolerate a few more aliens. I lack this ability to see into the future and consider that prevention is better than cure.

On the other hand, there are many plants so well established that I believe control would be impossible except in limited areas - a garden, for example. I took special note the other day of the distribution of Himalayan balsam along a river bank where it was established to the best of my knowledge more than fifty years ago. Someone suggested on another thread that it should be taken out because it re-structures river banks. This is nonsense. It helps to stabilise the bank in the same way as does the rest of the vegetation with which it shares space - mainly nettles, goosegrass, dock, ground ivy (another alien), various umbelliferae (incl. giant hogweed), mugwort, mint ... None of which it appears to have inconvenienced in the least. Furthermore there were bees laden with its pollen, and nothing else that they could harvest.

So I repeat, is there likely to be any action? If so is it likely to be effective? Would it not be more effective to be more critical of new incoming species?

[Hornbeam]

How long does an alien have to be here before it is considered to be a "native"? Surely almost all of our wild plants have arrived from elsewhere since the end of the last glaciation. They were all "aliens" and would have out-competed other plants. Now we have the dilemma of management. If we allow aliens to spread unchecked then we lose the wild landscape (eg rhododendrons in Wales). If we attempt to destroy the aliens then we conflict with natural succession. Either way, we finish up with a managed landscape.