How should we treat Garden Escapees

[Jez]

If at all?

[nightshade]

some are too invasive to leave alone,others have been naturalising for years

[aeshna5]

Most are benign, but there is a minority of highly invasive species that get the headlines such as Himalayan Balsam, Rhododenron ponticum, Japanese Knotweed.

Plants have escaped into the wild since Neolithic farmers arrived with Field Poppies, Corncockles, etc escaping as contaminants from early crops. Even plants such as White Dead-nettle are not native, even though they have been around many centuries now.

Though we should exercise some caution about new species in the wild, I think it is simplistic + naive to consider alien = bad + native =good. One of our most invasive plants is native- Bracken.

London Rocket which is an alien even has a Biodiversity Action Plan to conserve it!!

Many aliens are useful to native wildlife-look at the insects attracted to Buddleja davidii + Red Valerian.

I think each case needs to be looked at individually, but our flora is far from native, about half are already aliens, whether archeophyte or neophyte.

[Jez]

Have learnt a great deal from two replys, many thanks both!

[Jez]

It's an ever changing world

[JonSadler]

You could be mischievous and say it doesn't matter at all because nothing is really native. Eighteen thousand years ago a few miles from me there was a 2 km thick ice sheet sat on the country. Since then everything we consider native has colonised us in some way or other. Humans have exacerbated it but the process of immigration and extinction has been a constant since the last ice age receded. It is not a surprise that we don't have too many endemic species.

However, I agree with others that some of the aggressive species (the big three, H. Balsam, Giant Hogweed, J. Knotweed) need control.

And that Anemone is a beautiful flower.

Regards
Jon

[ceterach]

Bit of a slow reply I know but I thought I would add my twopennyworth!

The BSBI have addressed this (Alien Invaders?) and come to the same broad conclusion as Aeshna and in general I think this is correct.

Originally Posted by aeshna5

Most are benign, but there is a minority of highly invasive species that get the headlines such as Himalayan Balsam, Rhododenron ponticum, Japanese Knotweed.

However, I am involved in the management of several sensitive suburban sites (including two SSSIs) that have come under threat from a number of escaped/deposited species that have had to be removed at considerable expense in terms of time. The best example is Canadian Golden Rod (Solidago sp) on chalk downland. This plant spreads both by seed and vegatively and unless controlled takes over large areas. So far it has shown little evidence of settling down in a balanced existence with the existing flora inexorably forming larger and larger clumps even on the most nutrient-poor sites(albeit in that case with stunted growth). This excludes other more fragile species on a habitat already under threat from other factors.

The problem is exacerbated in that there seems to be a general feeling that it is acceptable to dispose of garden waste on natural sites willy nilly and the practice seems to be increasing. We even have problems with spring bulbs especially Daffodils that have been planted to "brighten the place up", it is surpising how quickly they begin to form very large clumps. I could list a lot more!

Originally Posted by aeshna5

I think each case needs to be looked at individually, but our flora is far from native, about half are already aliens, whether archeophyte or neophyte.

I think this is the real point! In particular I don't think it is sufficient to just let nature take it's course on highly pressurised sites and we must be constantly on guard for local effects at a time when in many areas "natural" habitat is increasingly restricted wildlife to smaller and smaller areas.

All the best