Alien plants

[Alan]

Originally Posted by Hornbeam

Yes. I was using the term "wood pasture" as a short cut all embracing term for all of the chain-sawing that goes on. The point that is lost is that in earlier times, coppicing and pollarding were carried out to produce a useful crop of poles for buildings, fences and tools. The aim was not to improve biodiversity. With the fad for putting cattle in our forests, will we also see a return of pannage? Go photograph those helleborines now folks before Miss Piggy gobbles them up.

Yes I see what you mean. Maybe the return to 'wood pasture' which doesn't entail chopping down trees, is thought of as some, as a cheaper alternative to using manpower to control 'overgrown' areas or coppice them, or even as a way of attracting tourists!

Also you could say that the miss piggy you are talking about is just a replacement of Wild Boar, another thing that many would like to see re-introduced. One of the reasons we have a lot of bluebell woods in this country compared to mainland Europe, is that lack of these! But Wild Boar have benifits too, swings and roundabouts again!!

[Gill Catton]

Originally Posted by Hornbeam

Yes. I was using the term "wood pasture" as a short cut all embracing term for all of the chain-sawing that goes on. The point that is lost is that in earlier times, coppicing and pollarding were carried out to produce a useful crop of poles for buildings, fences and tools. The aim was not to improve biodiversity. With the fad for putting cattle in our forests, will we also see a return of pannage? Go photograph those helleborines now folks before Miss Piggy gobbles them up.

It's such a shame there's no longer a market for such poles I hate it when I see hedges layed or trees coppiced and pollarded and the wood just piled up and burnt, such a criminal waste, there must be generations of woodsmen spinning in their graves....... If they were to add cows and pigs I wish they'd remove some of the deer first my local woods - even in my lifetime - they have grazed so much of the ground flora with riddled it with bare earth tracks too many deer and nobody eating them...... what the place would be like with the addition of cattle and pigs - even primitive breeds- doesn't bare thinking about!!

[Alan]

It's interesting, as around these parts there's a decided lack of browsers in the way of deer etc. In most of these woodlands that aren't managed to any degree, the understory is often impassable in the summer months!

Again it alway seems to come down to balance. If there's too many deer, what controls them if we dont? Another topic for another thread maybe!!

[eeyore]

Originally Posted by Gill Catton

It's such a shame there's no longer a market for such poles I hate it when I see hedges layed or trees coppiced and pollarded and the wood just piled up and burnt, such a criminal waste, there must be generations of woodsmen spinning in their graves....... If they were to add cows and pigs I wish they'd remove some of the deer first my local woods - even in my lifetime - they have grazed so much of the ground flora with riddled it with bare earth tracks too many deer and nobody eating them...... what the place would be like with the addition of cattle and pigs - even primitive breeds- doesn't bare thinking about!!

A number of woodland managers etc are tring to develop a market for woodland produce - One such is the bioregional charcoal company which acts as a cooperative to give small woodland managers more clout in the supply chain - they have just won a contract to supply B+Q with sustainably produced british charcoal.

Others are working on creating a market for coppice generated firewood , for poles for use in the garden instead of bamboo, for hurdles as fencing, and many other markets

Originally Posted by hornbeam

The point that is lost is that in earlier times, coppicing and pollarding were carried out to produce a useful crop of poles for buildings, fences and tools. The aim was not to improve biodiversity

The fact that in earlier times the work was not carried out for biodiversity aims does not mean that such work did not have biodiversity benefits. It would not be appropriate for me to comment on the management practices at epping but as far as woodland i have worked in go we gave always been very careful to manage the work so that the impact on bluebells etc is minimized , as I i said above coppicing per se will not harm a bluebell woodland as the overstorey layer is not harvested just the coppice stool layer - thus the light level at the woodland floor is not greatly increased

[Imaginos]

Originally Posted by eeyore

as I i said above coppicing per se will not harm a bluebell woodland as the overstorey layer is not harvested just the coppice stool layer - thus the light level at the woodland floor is not greatly increased

True, however when returning a wood to a coppice regime, more often than not the coppice stool trees have gone so long uncut that they have become the overstorey. Coppicing in these conditions leads to a lot more light arriving at the floor between underdeveloped standard trees.

[Airehead]

Originally Posted by Imaginos

new invaders, but the finding and identification of these is fraught with difficulty.

I am sure this is true BUT-

Originally Posted by Imaginos

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.

- only if we have identified them early enough. You only need observation, not statistics, to tell you that no meaningful level of control has been found or is likely to be found for many invasive species once they have got a hold.
As a matter of fact, I happen to like statistics where they lead to efficient practice and have generated and used statistics myself in industry. But I question the economy of generating 'useful statistics' which are not being used. And, of course, economy is the bottom line where control is concerned; because it is simple enough to propose absolute control of any or all species - all we have to do is to find a bottomless well of resources (=man power = money). To put it another way, if I can keep the weeds down in my garden by constant effort then we can theoretically do it country-wide. It would solve unemployment. But the moment we stop, the wild wins. Eradication is a different matter from control and I believe in most cases is impossible. Yes, I know we don't have wolves or Beavers any more, but I think the post-glacial environment had a lot to do with that. And now, some twit wants to re-introduce those.

Originally Posted by Imaginos

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.

I must reiterate that in the case of H. balsam it demonstrably does not form a monoculture at least along the rivers of the Plain of York where it has been established for a long time and shares its ground with all the other plants.

[eeyore]

Originally Posted by Imaginos

True, however when returning a wood to a coppice regime, more often than not the coppice stool trees have gone so long uncut that they have become the overstorey. Coppicing in these conditions leads to a lot more light arriving at the floor between underdeveloped standard trees.

this is true in the short term but within one cycle (generally ten to fifteen years) the canopy layer will have developed and the coppice blocks will actually be denser at times than the neglected coppice.

In my experience the only time you get a real issue with too much ligh is when the overstorey is either harvested or blown down in storms , at this point a responsible woodland manager will need to find ways of controlling the bramble etc until the trees can be resestablished - we tend to use volunteer work parties and /or contractors with brushcutters.

[Imaginos]

Originally Posted by eeyore

this is true in the short term but within one cycle (generally ten to fifteen years) the canopy layer will have developed and the coppice blocks will actually be denser at times than the neglected coppice..

And how many shade loving plants and insects are able to survive in substandard conditions for ten-fifteen years? I know coppicing is done on a rotational basis so that in theory there is always some climax habitat available, but in practice it seems that fresh coppice allows invaders to establish (plant, insect or mammal) where they would not have if the woodland was retained in its pre-coppice management. Thus when the coppice reaches its 15 years it seldom resembles the original state. I appreciate that coppicing is good for some species of plant, bird and mammal, but remain to be convinced that a full understanding of a woodlands diversity (including insects) is reached before undertaking such drastic management in most cases. Something we are coming to realise as research goes on is that our rarer species in all taxonomic groups tend to be more conservative, less adaptable species which are unable to survive too much change; those species that are adaptable in the face of change tend to be the pest species (aphids, chickweeds, grey squirrels to name but a few). More land managers should be coming around to the view that "if it aint broke, don't fix it", but this is seldom the case nowadays

This is all very, very far from the original point of this thread which was looking at alien plants. With reference to Aireheads points; I am not talking about the gathering of data with the intention of short-term control efforts, I am thinking more about long-term monitoring of an invasive species in order to understand the ecology of invasion-something that is very poorly known at the moment. This can only be done with a great deal of observational help from members of the public, hence the call for sightings at the top of the thread.

Originally Posted by Airehead

I must reiterate that in the case of H. balsam it demonstrably does not form a monoculture at least along the rivers of the Plain of York where it has been established for a long time and shares its ground with all the other plants...

A couple of websites claiming otherwise are below, from both sides of the Atlantic. Without knowing much about your site on the Plain of York, I would guess that the plants sharing the ground would be some of our relatively common and competitive plants, e.g. nettle, dock, bramble, dead nettles,some common Asteraceae and the like. The Plain of York is an important area in Britain for Tansy beetle; does Tansy grow among the Balsam? I have heard that some autoecological studies in progress in Bristol are finding that H. Balsam is incredibly effective at outcompeting other species due (among other things) to it's rapid growth rate, rapid expansion of patches (due to their exploding seedpods) and also their flowers are more attractive to pollinators than native plants, none of this seems to be good news.

It is also worth noting that in other parts of the world biological control (when done properly) has been very effective in removing alien plants and insects, although only on a small-scale in most places.


http://www.wiltshirewildlife.org/Def...9CCD0667DEB%7D
http://www.shim.bc.ca/invasivespecie...yan_balsam.htm

[Alan]

I would have thought that if an area has been managed historically as a coppice for a length of time, it’s probably best to continue this management technique as the flora and fauna have adapted to it over time. If on the other hand if an area has no coppice history, I’d have thought it better to consider all management techniques including doing nothing and letting it continue to revert to a more wild state would be the way to go. I’d have thought that most would agree that a ‘blanket’ policy doesn’t do any habitat any good.

As regards Balsam, even if the plant doesn’t seem to be doing too much harm to the casual observer just by it being there, it takes up a position (displaces) the far more useful native plants, which will surely result in a loss of biodiversity of the habitat in question. Also, and as has been stated, the unknown factors are the things that matter. The only way these can be understood is surely through research.

[Airehead]

Originally Posted by Imaginos

Without knowing much about your site on the Plain of York, I would guess that the plants sharing the ground would be some of our relatively common and competitive plants, e.g. nettle, dock, bramble, dead nettles,some common Asteraceae and the like. The Plain of York is an important area in Britain for Tansy beetle; does Tansy grow among the Balsam?

Those are precisely the plants that it shares with - because they are the common plants and if it is going to share with anything it must be these. As for the tansy, and all the others -
The point about the mode of sharing is that the balsam does not take over the whole length of the bank by obliterating everything else. As you walk along the bank you pass areas which are predominantly one plant or another, commonly balsam + goosegrass, nettles + goosegrass, balsam + nettles, or areas with a mix of other species - dock, ground ivy, mugwort and various others. I have not made a point of observing the tansy, but I know I have seen it thinly scattered. I think it is one of the plants which grow more in the open at the top of the bank (the banks are steep) on the edge of the cultivated area of the field - as do poppies, for example. Balsam tends not to encroach here.
I think the most significant point is that if, as you say, the area is important for the tansy beetle, then it must be co-existing because, as I have said, the distribution of the balsam has not greatly altered in the 50 years since I first saw it. It was already established then. And if it were not there, then its ground would be just as heavily overgrown with nettles so that portion of the profile of the bank which is favoured by balsam and likewise by nettles would never be available for the tansy.
This is my observation, it is not an expert view.

[eeyore]

Originally Posted by Imaginos

And how many shade loving plants and insects are able to survive in substandard conditions for ten-fifteen years? I know coppicing is done on a rotational basis so that in theory there is always some climax habitat available, but in practice it seems that fresh coppice allows invaders to establish (plant, insect or mammal) where they would not have if the woodland was retained in its pre-coppice management. Thus when the coppice reaches its 15 years it seldom resembles the original state. I appreciate that coppicing is good for some species of plant, bird and mammal, but remain to be convinced that a full understanding of a woodlands diversity (including insects) is reached before undertaking such drastic management in most cases. Something we are coming to realise as research goes on is that our rarer species in all taxonomic groups tend to be more conservative, less adaptable species which are unable to survive too much change; those species that are adaptable in the face of change tend to be the pest species (aphids, chickweeds, grey squirrels to name but a few). More land managers should be coming around to the view that "if it aint broke, don't fix it", but this is seldom the case nowadays

obviously i cant comment on what all woodland managers do , but in our case all our woodland work is subject to management plans drawn up by extremley experienced ecologists who have upwards of 25 years experience of the sites in question, and who thus do have a full understanding of the woodlands diversity.

Also it is rarely the case that the whole woodland is put into rotaional coppice management, generally the aim of the practice is to diversify the habitat available and thus non intervention blocks are generally left between the coppiced areas