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.

[Airehead]

Originally Posted by 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.

True, and this is partly why I question the wisdom of trying to eradicate, e.g., Himalayan balsam.

However, one might conclude that all modes of arrival of plants into an ecology are acceptable other than by human agency. There is also the point that our landscape is 100% managed to the extent that it does not remotely resemble what it would have been if humans had not arrived here after the ice age. Of course, for a landscape to be described as 'wild', it must simply be left alone notwithstanding the presence of formerly alien flora and fauna. But it also means not allowing any more to escape out of our hands.

I note that in the recent issue of the 'Wildlife' magazine there is the proposal that we must now accept grey squirrels and forget the reds.

[Hornbeam]

Yes, I fully accept that all of our landscape is managed and none can be said to be "wild". Not sure where I stand on recent aliens, but I do hope that we have learned some lessons about importing potentially rampant garden plants. The other related issue that concerns me is over management. For example, there is at present an enthusiasm for wood pasture whereby attempts are made to reintroduce pollarding and coppicing. One of the justifications is that of letting light into a wood that will encourage a diverse ground flora. Maybe, but what seems to happen is that willow herb appears first, followed by creepng thistle and then great thickets of bramble. The losers are wood anemones and bluebells. Those flowers bloom before the tree canopy comes into leaf, but bramble flowers later when the trees are in leaf and the ground is in shade. Remove the shade and the bramble is given the light previously denied it. Such well intentioned management is disastrous for the bluebell wood. However, the rampant bramble is native and not an alien so should we allow it to grow unchecked or treat it as we do rhodos, balsam and Japweed? The bramble is a great food plant for insects though, but how much is too much?

[eeyore]

Originally Posted by Hornbeam

Yes, I fully accept that all of our landscape is managed and none can be said to be "wild". Not sure where I stand on recent aliens, but I do hope that we have learned some lessons about importing potentially rampant garden plants. The other related issue that concerns me is over management. For example, there is at present an enthusiasm for wood pasture whereby attempts are made to reintroduce pollarding and coppicing. One of the justifications is that of letting light into a wood that will encourage a diverse ground flora. Maybe, but what seems to happen is that willow herb appears first, followed by creepng thistle and then great thickets of bramble. The losers are wood anemones and bluebells. Those flowers bloom before the tree canopy comes into leaf, but bramble flowers later when the trees are in leaf and the ground is in shade. Remove the shade and the bramble is given the light previously denied it. Such well intentioned management is disastrous for the bluebell wood. However, the rampant bramble is native and not an alien so should we allow it to grow unchecked or treat it as we do rhodos, balsam and Japweed? The bramble is a great food plant for insects though, but how much is too much?

Properly managed coppicing doesnt result in this because you are not removing the over storey of oak or ash, just stooling the copice layer (usually hazel or sweet chestnut) , in my experience you get a major vburst of wildflowers on the coupes in year 2 , followed by taller herb layer species etc in 3 and 4 before the hazel reasserts itself.

as coupes are rotated on a ten - fifteen year cycle there is always one which has open flora and the others are at diverse stages of growth creating a range of habitats and generally providing better habitat for wildlife.

[Airehead]

Originally Posted by Hornbeam

Not sure where I stand on recent aliens, but I do hope that we have learned some lessons about importing potentially rampant garden plants.

Concerning the more general issue of all alien species, plant and animal, I don't think we have learned anything, partly because each new generation in its youthful enthusiasm and misplaced confidence just goes blinding ahead by repeating the mistakes of its forefathers. I must again cite Harris hawks and African snails, re my earlier posting. Everyone is apparently satisfied with closing the stable door after the horse had bolted.

Originally Posted by Hornbeam

The other related issue that concerns me is over management. For example, there is at present an enthusiasm for wood pasture whereby attempts are made to reintroduce pollarding and coppicing.

Again, the same enthusiasm as of children with a new toy.

[eeyore]

Originally Posted by Airehead

Again, the same enthusiasm as of children with a new toy.

or the enthusiasm of a conservation land management specialist with over 15 years experience it all depends on your point of view

[Airehead]

Originally Posted by eeyore

or the enthusiasm of a conservation land management specialist with over 15 years experience it all depends on your point of view

Those who are asking themselves whether they have done the 'right thing' in uprooting H. balsam do not fall into this category.

And anyone who does, but imagines he/she can predict the long-term outcome of allowing a new alien species to escape has not learned much in 15 years.

[eeyore]

Originally Posted by Airehead

And anyone who does, but imagines he/she can predict the long-term outcome of allowing a new alien species to escape has not learned much in 15 years.

But probably has a better chance of knowing what they are talking about than someone who doesnt work in the field at all

BTW i was talking about the coppicing issue - most land managers who practice this are dedicated proffesionals with a huge degree of knowledge of woodland management, not generally described as those "playing with their new toys"

[Airehead]

Originally Posted by eeyore

most land managers ,

It would seem reasonable to suppose that these are not the ones included in the phrase "at present there is an enthusiasm"

[eeyore]

Originally Posted by Airehead

It would seem reasonable to suppose that these are not the ones included in the phrase "at present there is an enthusiasm"

I'm not sure what point you are trying to make here, and I really cant be doing with yet another argument over semantics of discussion.

Most managers of woodlands sites do embrace coppicing and wood pasture as part of their repetoire, the growing number of woods brought back into propper masnagement , might well be seen as an enthusiasm for the technique , but it is one based on tried and tested methods. which while they might look drastic to the uninitiated are proven to be beneficial to wildlife in the long term

[Airehead]

Originally Posted by eeyore

I'm not sure what point you are trying to make here,

The main point was a straightforward question which I asked at both the beginning and end of my 2nd posting on this thread, but as you have done in other threads you have chosen to take up a minor issue and worry it ragged, ignoring the main point - or more likely, never having read it.

[eeyore]

Originally Posted by Airehead

The main point was a straightforward question which I asked at both the beginning and end of my 2nd posting on this thread, but as you have done in other threads you have chosen to take up a minor issue and worry it ragged, ignoring the main point - or more likely, never having read it.

i wouldnt call one post correcting a misaprehension about woodland management worrying anything ragged.

and as i have said to you before as far as going ignoring the main point goes , well people who live in glass houses shouldnt throw stones

For the record i did read your posts , and actually found some of them to be interesting and insightful, it is a great shame you didnt accord me the same courtesy.

[Imaginos]

The ancient practice of coppicing in modern Britain causes its own problems in many areas, for example where deer have become established in any sort of numbers. One woodland which I studied in Essex a few years ago had lost most of its coppice trees to grazing of new shoots by fallow and Muntjac Deer and had been more or less ruined as a site for ground- and shrub layer-nesting birds as a consequence. The manager of the wood (a man with 30+ years of experience) had assumed that, although the deer were evidently a problem the coppice rotation and ineffective electric fences would alleviate grazing in any one area (and other wooly arguements which the mists of time have clouded in my memory). The gist of this being that 'tried and trusted' methods handed down from our forefathers need to be re-evaluated in todays changing climate and ecology

Back to the main point of Aireheads: yes it would be well to concentrate critically on new invaders, but the finding and identification of these is fraught with difficulty. Also only some of these new aliens would succeed where most will fail, meaning that effort could be wasted studying or eradicating a species that isn't going to cause a problem. There are certain established invasive species that we know are environmentally degrading, forming virtual monocultures over patches of land that would otherwise be more biodiverse. Such plants include Balsam, Pygmyweed and Knotweed. Finding out where these plants are in the country is a first step towards management plans to eradicate, or at least control them, as has been done to a certain extent with Rhodedendron which is usually quite closely controlled in environmentally sensitive areas, although obviously not where Airehead spotted it in Scotland. Incidentally, some authorities believe that Rhodedendron is technically a native, having been in Britain in the pre-glacial period before dying out and there is a remnant population in S. Spain.
Airehead asks the question whether the gathering of data does any good, in my opinion you cannot have too much data, ever. Whether the results are acted on or not the data is useful in itself. If we can, for example, model the spread of New Zealand Pygmyweed then we have an insight into the ecology of an invasive species which could lead to better control methods in the future, either in this country or abroad.

[Hornbeam]

[quote=Imaginos]The ancient practice of coppicing in modern Britain causes its own problems in many areas, for example where deer have become established in any sort of numbers. One woodland which I studied in Essex a few years ago had lost most of its coppice trees to grazing of new shoots by fallow and Muntjac Deer and had been more or less ruined as a site for ground- and shrub layer-nesting birds as a consequence. The manager of the wood (a man with 30+ years of experience) had assumed that, although the deer were evidently a problem the coppice rotation and ineffective electric fences would alleviate grazing in any one area (and other wooly arguements which the mists of time have clouded in my memory). The gist of this being that 'tried and trusted' methods handed down from our forefathers need to be re-evaluated in todays changing climate and ecology.[quote]

Exactly - thank you Imaginos!
I may be one of the "uninitiated" but I do understand the theory behind wood pasture - just don't think it works. I have been monitoring three local woods for 32 years and can show before and after photos that will make you weep. Sheets of bluebells and anemones replaced by tangled thickets of willowherb and bramble. Clearings made to let in light for wild flowers, but the deer and cattle graze away everything except brambles and thistles. No joined up thinking. Even the new guy in charge of Epping Forest is reported to have said that a policy of wood pasture will be applied to the entire forest (plus more cattle) Anyone familiar with the magnificent and enormous trees of Epping will shudder at the thought of them being reduced to stumpy green lollipops. Fashions change and hopefully the tidy-up managers will develope new and less harmfull enthusiasms.

[Alan]

Originally Posted by Hornbeam

Exactly - thank you Imaginos!
I may be one of the "uninitiated" but I do understand the theory behind wood pasture - just don't think it works. I have been monitoring three local woods for 32 years and can show before and after photos that will make you weep. Sheets of bluebells and anemones replaced by tangled thickets of willowherb and bramble. Clearings made to let in light for wild flowers, but the deer and cattle graze away everything except brambles and thistles. No joined up thinking. Even the new guy in charge of Epping Forest is reported to have said that a policy of wood pasture will be applied to the entire forest (plus more cattle) Anyone familiar with the magnificent and enormous trees of Epping will shudder at the thought of them being reduced to stumpy green lollipops. Fashions change and hopefully the tidy-up managers will develope new and less harmfull enthusiasms.

It’s worth pointing out that ‘wood pasture’ and ‘coppiced woodland’ are different things.

Wood pasture is created by allowing deer sheep and other livestock to browse the underbrush. One of the aims of this in relatively recent times is to preserve the biodiversity of this particular type of habitat by using the animals. Of course it depends on exactly which species you want to preserve. Some benefit from grazing, some don’t.

Coppiced woodland by its very nature requires most of the trees to be cut leaving ‘stools’ to grow-on. Even here though, many ‘standard’ trees are left standing, and as has been stated, it’s done on a rotation.

It’s also worth mentioning that just because an area used to be full of Bluebells etc, if left to it’s own devices, and through natural succession if you will, that area would have resorted to dense scrub anyway, and so the Bluebells may go the same way.

A habitat doesn’t stay in a time warp, it’s only when humans become involved with their ideas of what ‘natural’ or ‘wild’ is that it does. An area of thick Brambles still supports a vast array of species, even if it doesn’t look as pretty as a Bluebell area.