The UK is full of non-native species and here is Wessex we have our fair share. Some species have been here so long they seem like natives, such as shepherd's-purse (Capsella bursa-pastoris) and some of them are welcome, like the orange hawk-weed (Pilosella aurantiaca) in my lawn. But some are not welcome at all, because they are agricultural pests or they are invasive. By that, we mean that they take over the ecological niches occupied by native plants and cause a local drop in plant diversity or even local extinctions. So it is never a case of of "native good, alien bad"; there is much to be gained from active and determined management of the issue.
No one should be in any doubt as to the severity of the issue. World-wide, alien invasive species is one of the top three or four reasons for the accelerated extinction rate we are experiencing in modern times. In the UK, we like to lay blame and the finger is most often pointed at the horticultural sector.
In some quarters, the debates that go on about this topic are becoming confused. None more so than in horticultural circles where people can feel a bit embattled. A recent letter in the Royal Horticultural Society's magazine "The Garden" is a case in point. A paper published by two academics was described as if it was more authoritative than it really deserved.
So I quickly penned a reply back and I am glad to say that it is published in the latest issue of "The Garden".
Non-native species
Your headline ‘No countrywide threat from non-natives’ (News, May, p10) was overly simplistic. Thomas and Palmer’s paper has been quoted as if it were the last word on the subject. The effect is to cloud the issues around biodiversity conservation in the UK.
The lack of increase in non-native species observed in the Countryside Survey data (the raw data on which the research was based: no new field data was gathered) may well be due to the huge effort being taken to combat them. Between £1–2billion a year is spent in the UK to control and eradicate non-native plant species; this obviously affects the distribution of their populations. That we have still not succeeded in saving our precious landscapes, despite this considerable expenditure, shows just how intractable the problem is.
Habitat loss is the main driver of the loss of biodiversity, but not usually the total destruction of a wood, heath, mire or moor. Rather it is the gradual degradation of the habitat’s quality, a major cause of which is the effect of non-native plants. For instance, an ancient oak woodland may be protected in that the trees cannot be cut down. But if cherry laurel (Prunus laurocerasus) or Rhododendron x superponticum are present, and unless they are controlled and ultimately eradicated, the writing is on the wall for that entire fragile plant community.
Professor Thomas’s bizarre point of view that non-native plants have ‘supplemented, rather than excluded, native species’ is not supported by the experience of decades.
A chalk stream’s riparian plant community is not ‘supplemented’ by Himalayan balsam (Impatiens glandulifera); the presence of Japanese knotweed (Fallopia japonica) is indeed a threat to any UK native habitat. I work for one of the 46 Areas of Outstanding Natural Beauty, in every one of which we are fighting to save our wild plants at landscape scale. I feel that giving this single study such prominence can only cause confusion.
For more information about this subject, or to join the debate, have a look at Trevor Dines' blog http://www.plantlife.org.uk/about_us/blog/loving_the_alien
No one should be in any doubt as to the severity of the issue. World-wide, alien invasive species is one of the top three or four reasons for the accelerated extinction rate we are experiencing in modern times. In the UK, we like to lay blame and the finger is most often pointed at the horticultural sector.
In some quarters, the debates that go on about this topic are becoming confused. None more so than in horticultural circles where people can feel a bit embattled. A recent letter in the Royal Horticultural Society's magazine "The Garden" is a case in point. A paper published by two academics was described as if it was more authoritative than it really deserved.
So I quickly penned a reply back and I am glad to say that it is published in the latest issue of "The Garden".
Non-native species
Your headline ‘No countrywide threat from non-natives’ (News, May, p10) was overly simplistic. Thomas and Palmer’s paper has been quoted as if it were the last word on the subject. The effect is to cloud the issues around biodiversity conservation in the UK.
The lack of increase in non-native species observed in the Countryside Survey data (the raw data on which the research was based: no new field data was gathered) may well be due to the huge effort being taken to combat them. Between £1–2billion a year is spent in the UK to control and eradicate non-native plant species; this obviously affects the distribution of their populations. That we have still not succeeded in saving our precious landscapes, despite this considerable expenditure, shows just how intractable the problem is.
Habitat loss is the main driver of the loss of biodiversity, but not usually the total destruction of a wood, heath, mire or moor. Rather it is the gradual degradation of the habitat’s quality, a major cause of which is the effect of non-native plants. For instance, an ancient oak woodland may be protected in that the trees cannot be cut down. But if cherry laurel (Prunus laurocerasus) or Rhododendron x superponticum are present, and unless they are controlled and ultimately eradicated, the writing is on the wall for that entire fragile plant community.
Professor Thomas’s bizarre point of view that non-native plants have ‘supplemented, rather than excluded, native species’ is not supported by the experience of decades.
A chalk stream’s riparian plant community is not ‘supplemented’ by Himalayan balsam (Impatiens glandulifera); the presence of Japanese knotweed (Fallopia japonica) is indeed a threat to any UK native habitat. I work for one of the 46 Areas of Outstanding Natural Beauty, in every one of which we are fighting to save our wild plants at landscape scale. I feel that giving this single study such prominence can only cause confusion.
For more information about this subject, or to join the debate, have a look at Trevor Dines' blog http://www.plantlife.org.uk/about_us/blog/loving_the_alien
No comments:
Post a Comment