16 March 2011

Alien plants

Yesterday I came across a single plant of Eastern Sowbread (Cyclamen Coum) growing in a semi-natural situation on the bracken slopes above Penclawdd rugby fields. I'm not sure it's likely natural dispersal resulted in it appearing in the middle of  dense Bramble thicket and I suspect that it was either planted or a garden thrown out. Other more established non-native species noted on the hillside included Japanese Knotweed (Fallopia japonica) and Himalayan Honeysuckle (Leycesteria formosa).
The BSBI website reports that there are 1500 native species in Britain and around about 1700 aliens! I found the following paragraphs quite interesting reading... 'The danger with viewing alien species as a particular threat is that it distracts from the important issues facing nature conservation in Britain and diverts resources that might be better used elsewhere. When an individual species becomes overwhelmingly abundant in a particular habitat, it is usually because that habitat is being mismanaged or polluted – for example, by eutrophication. It does not matter whether the problem plant is native or exotic: the best solution is to restore a healthy vegetation community, not to attempt to eradicate one species whilst leaving the underlying problems unaddressed. Thus there seems little point in spraying a road-verge to eliminate Japanese Knotweed, just to leave the brambles, coarse grasses and even the frequently-invasive Cow Parsley to take its place.
The subjects of ecosystem stability, invasiveness of individual species, and habitat management are all promising ones for research, and might appeal to students or researchers at postgraduate level. Surprisingly, perhaps, although the UK government has a policy of eradicating New Zealand Pigmyweed, there is no published evidence whatsoever that it harms native species. Another common alien aquatic invader, the attractive Himalayan Balsam, is a frequent subject of vilification, with even less evidence of any threat to anything. The only way to formulate good policy is to base it on firm evidence, and that has clearly failed in these instances. There is now available good research information which suggests that the threat from Japanese Knotweed is minor, and it is even viewed by some as beneficial (Gilbert, 2001), yet hysteria on this species regularly surfaces in all sections of the media.'

1 comment:

Anonymous said...

Thanks for that, very thought provoking.