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Low impact removal of big trees?

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Re: Low impact removal of big trees?

Postby RichardKing » Wed Jun 13, 2012 7:19 pm

You are starting from the premise that it "needs thinning"
If you want to harvest some timber just go ahead & say that.
Over time the trees have created their own environment in the woodland.
Do you wish now to modify the environment to create some idealised human concept of a woodland ?
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Re: Low impact removal of big trees?

Postby Stephen1 » Thu Jun 14, 2012 10:56 am

My view on this is one of absolute agreement with RichardKing.
Conservation "Management" is a very complex area - and this is particuarly true of woodland in the UK (if you're interested then ask me why, otherwise this post will get too long!)
Biodiversity has come to be a kind of proxy for the conservation value of an area of land. The higher the biodiversity the better.

This is very unfortunate thinking, and has come about because we live in a day and age when everything has to be reduced to easily understood soundbites. The concept of maximising biodiversity as unquestionably being the best course of action is only appropriate at the landscape scale. Where the piece of land being managed is relatively small other less easily measured parameters may be paramount.

If you have an area of woodland that has been undisturbed for a long tim,e then this may be described as being on a trajectory towards "old growth" habitat. A very rare and very valuable habitat in the UK - with very specific species associated with it. Old growth habitat is characterised by big old trees, lots of deadwood (on the floor and standing) and lots of shade. It has fewer of the 'showey' species associated with coppice, and possibly less species than areas of woodland that have been well managed as coppice for a long time. But does that make it less valuable?
Coppice mimics what happens when a large gap (wind,disease etc.) was made in the original 'wildwood' - you get a flush of light-adapted species. For most of the last couple of millenia in the UK our coppice woodlands have sat in an agricultural landscape and so grassland species also disperse into the light flooded gaps that coppicing creates - it's a kind of unstable hybrid of two habitats and this is reflected in the apparent high species count. It undoubtedly has high biodiversity and you can see the results of your efforts quickly.
The big worry for the areas of shady 'older' growth woodland in the UK is that new managers come in and decide to increase the biodiveristy by letting the light in. The idea being to get the best of both worlds - they keep some old trees with all the more cryptic species associated with old growth, and get the 'Gap phase' species associated with light.

Unfortunately there is a problem with that. Most of this management goes on at a small scale. (I notice that most woodlands sold by woodlands.co.uk are around 5 acres or so, and I believe lots of folk here have bought through them?) It ignores a concept every bit as important as biodiversity and that's bioresilience. If I fell half the old trees I half the populations of lichens, invertebrates etc. associated with them, I also half the populations of 'boring' hard-to-identify bryophytes adapted to deep shade on the woodland floor. These species are very slow to disperse and increase their populations - and even when coppicing stops take a very long time to recover. By coppicing such areas I immediately increase the apparent biodiversity, but I do it at the expense of the bioresilience of the species adapted to the shadey old growth woodland habitat.

Imagine a 5 acre wood bought as a conservation project. It's been "neglected" since felling took place during the last war - a very common situation for farm woods in the UK. The new owners decide to increase the biodiversity by starting a program of coppicing. They start a ten year cycle of about half an acre a year but to get thing's going they to "open up" all the rides, create glades throughout the woodand including one of about half an acre which they clear and sow with a wildflower meadow mix, and as the jewel in the crown of their conservation project fell another half acre to create a half acre pond. Also because the hazel is in so much shade and isn't looking "Healthy" they decide to thin out half the standard oaks straight away. Biodiversity, in terms of number of species present, dramatically increases. At the end of ten years to the human eye the woodland is alive - butterflies, carpets of wildflowers- wonderful!
But all those species that needed undisturbed, shadey older growth are suffering; the bulin snails, the slugs, many non-obvious fungi, bryophytes, arthropods etc. their popuations are drastically reduced and many become non-viable. Over time these species are lost from the wood - but people don't notice because they are hard to spot and identify and also because we are culturally unaware of them.
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(humans spend time in woods that humans spend time in! Circular I know but we tend as a culture to know the species associated with woodland that is managed by humans - so we value primroses, bluebells etc. at artifically high numbers because that is what our culture expects from woodland - we expect woodland to be full of 'healthy' trees standing vertically with plenty of light and lots of spring fowers - these are the things we value, talk about, recognise, know the the names for and want)
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The 'old growth' species that start to get lost from the wood do so because the bioresilience of these species is reduced; their populations are reduced through lack of habitat (i.e.old trees, shadey floors (let the light in and they are out competed by 'gap phase species') Not only are their population numbers reduced but so too is the genetic diversity of their populations. Meaning they are less able to cope with specific problems that may happen i.e. unusual weather patterns or disease etc. Most significantly even if the coppicing program is abandoned and the wood is 'neglected' again those 'older growth' species that remain will have very restricted genetic diversity, and so are at greater risk of being lost at sometime in the future - perhaps even centuries down the line.

The reducution in 'older growth' species, and the reduction in the bioresilience of the 'older growth' species that remain is permanent.
The new owners are pleased with their work 'rejuventaing' the wood - and that's what they've done- they've made it young again.
These days woodland ecologists no longer subscribe to the myth of a climax stable state woodland, they realise it changes over time and may shift from dominance by one type of tree to another, but it does remain woodland without human intervention (ice-ages not withstanding!) and the evolutionary strategies of many of its denizens reflect that stability. Of course there were also species originaly associated with the gaps created by wind, tree death etc. These species have come to be associated with man's activities in woodland coppicing, felling etc. and they have become over-important to us culturally at the expense of those species that require deep old shadey stability.

When people talk about increasing biodiversity and in the next breath mention improving the health of the hazel coppice by letting light in -without wanting to cause offence I suggest that they are confused. If hazel has lots of light and thus is able to make lots of energy it can produce lots of chemicals that fight of fungi and reduce insect predation on it's leaves. For example hazel is prone to honey fungus in the shade but not when grown in the light. But that honey fungus, those insects feeding on it's leaves, the dead hazel stems full of beetle grubs and the birds eating the insects that the hazel can't fight off because it doesn't have enough energy to make the phytochemicals that stop the caterpillars/aphids etc. feeding on its leaves - that IS the biodiversity. Humanwise "heathy" hazel growing in lots of light supports much less biodiversity.

The 'rejuventaing' action of human choice isn't always ideal for woodland, it brings forth the flowers and butterflies, but lets have some respect for the Old who like to stay hidden away. Don't confuse increasing the conservation value of an area of woodland with merely increasing the biodiveristy (in terms of species count) by creating what actually amounts to a mosaic of different habitats on a scale too small to also benefit the bioresilience of existing species of value in your patch. A patchwork of different habitat types is what is needed at the landscape scale, and biodiveristy needs to be measured at a landscape scale - small areas need careful consideration in terms of what is 'best' to do and the pursuit of "biodiversity" increases can often be a redherring at this scale.
Last edited by Stephen1 on Thu Jun 14, 2012 11:50 am, edited 5 times in total.
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Re: Low impact removal of big trees?

Postby Stephen1 » Thu Jun 14, 2012 11:08 am

I'm using the terms old and older growth in a non-standard way above - in the context of this thread I hope it can be seen I'm using them in a relative way, and not in the way they are used in North America or mainand Europe, or even by some woodland ecologists in the UK.
Also I'd just like to point out that it is vanishingly unlikey that oldclaypaws woodland was planted in the middle ages. For many areas of southern and central England we have many very good records of land management, and the planting of woodlands during this period was very very rare- exceedling rare. Oliver Rackham is the authority on this and there is some information about the matter in his book "Ancient Woodland".


If the previous post is too long for this forum then no offence taken if one of the mods wants to remove it!
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Re: Low impact removal of big trees?

Postby splodger » Thu Jun 14, 2012 11:45 am

great post stephen (and i don't think the post is too long at all) in fact i think some people will appreciate the time and effort you have taken to write it

i do think that this thread might be better placed in the forum that covers topics on trees though - so if nobody objects, i'd like to move the whole thread there (i'll do it later today if nobody minds)

getting back to some of the points being raised, i do tend to agree with the idea that clearing, coppicing, modern woodland management etc does little to increase the true biodiversity of a patch of woodland.

but having read oldclaypaws post again, i'm not sure that is the main issue - i get the feeling that he wants to change as little as possible - and just wants a safe and healthy enviroment to work, rest and play in
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Re: Low impact removal of big trees?

Postby greyman » Thu Jun 14, 2012 12:42 pm

Stephen1 and Richard,
Stephen,
Your post is erudite and full of interesting information but my reading of the original post by Oldclaypaws is that he asked for some information/suggestions on how to clear some trees he was considering felling without too much impact. You are of course entitled to your opinions and you seem to be very knowledgeable but for me huge post's of this nature feel to me rather hectoring and I would be somewhat put out if directed at me if I asked what I thought was a reasonable question. This, is of course, just my view and Oldclaypaws looks to be able to put his thoughts forward and stand up for himself - I just wonder if we really want this level of counter agruement to a civil question.
Richard,
As above, but also I don't think Oldclaypaws is using the points raised in his question as a cover for just getting in there and felling trees. He asked what method others could suggest to minimise impact to his land.

I may, of course, have totally missed the point and have missed both of your intended well meaning points.

Greyman
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Re: Low impact removal of big trees?

Postby Stephen1 » Thu Jun 14, 2012 1:05 pm

Thank you Splodger. I'm always aware my posts tend to go a bit and I woudn't want anyone to think I was trying telling them what to do!

I think there is a place for coppicing - but this would be in woods where there was a recent history of coppicing (i.e. traditional coppicing having ended no more than about 50 years ago, but obviously this will vary depending upon very locally specific circumstances - and there would always be room for debate over the appropriate area to coppice, clearly I would suggest there to be no need, or wish, to reinstate the whole of the original area).

There is also a good argument to be made for artificially creating very small glades and small gaps within woodland. Most woodland in the UK has very few large old trees and so the rate of natural gap formation (i.e. wind/disease) from tree falls is lower than it would naturally be - and Gap Phase species are an important natural and desirable component.

Oldclaypaws asks for suggestions;

I would say this woodland represents a wonderful opportunity to create Old Growth 'style' conditions relatively quickly. It has had nearly a century of non/little intervention, and has thirty 120+ year old oaks per acre. In my opinion I would suggest to Oldclaypaws to be bold and to mimic the effects of even greater age on a third or so of these 120+ year old oaks. I would get a couple of tree surgeons to climb into the canopies of these trees and create cavities of many shapes and sizes. The idea is to get some holes and rot into the canopies of these trees and create the ecological architecture of oak trees that are a 250 years old. You can't really do this on oaks much less than 100 years old because you need the diameter (so the middle of the timber is insulated from rapid temperature and moisture fluctuations).

Examples of what I'm suggesting are described here;

http://www.naturalforestpractice.com/ca ... ytrees.htm

http://www.naturalforestpractice.com/ho ... rgeon.html

By taking this approach the wood could really become something rare and special over the next ten years - the starting conditions you have offer a very rare opportunity. By thinning the wood you'll turn it into a modern foresters idea of a "healthy" woodland and it will become just like innumerable other woods. The cost would be less than that of the thinning, and without the problems associated with felling and extracting the timber. What could be more low impact?

(For what it's worth if you explore more of Iliff's website above I believe him to be a visionary woodsman - I agree with most of his conclusions but not always for the reasons he arrived at them! A wonderful man to spend some time with- if you get the opportunity to meet him take it!)
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Re: Low impact removal of big trees?

Postby splodger » Thu Jun 14, 2012 1:21 pm

oldclaypaws - you are quite right really - as you're damned if you do / damned if you don't - life is so fickle ;)

in this virtual world of forum land - i can't see how anybody can give you great advise tbh - as each patch of woodland will be quite different from another - seeing first hand is really the only way that certain questions may be answered ;)

i think at the end of the day - you've just got to observe closely everything around you - take the time to enjoy your wood and time to understand it - as you get to know your patch intimately - you'll be in the best position to decide what needs doing
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Re: Low impact removal of big trees?

Postby Stephen1 » Thu Jun 14, 2012 1:39 pm

greyman wrote:Stephen,
Your post is erudite and full of interesting information but my reading of the original post by Oldclaypaws is that he asked for some information/suggestions on how to clear some trees he was considering felling without too much impact. You are of course entitled to your opinions and you seem to be very knowledgeable but for me huge post's of this nature feel to me rather hectoring and I would be somewhat put out if directed at me if I asked what I thought was a reasonable question. This, is of course, just my view and Oldclaypaws looks to be able to put his thoughts forward and stand up for himself - I just wonder if we really want this level of counter agruement to a civil question.


This crossed with my last post. You may have noticed my embarrassment and concern about the appropriateness of such a long post myself in the post I immediately followed it with (I suggested a moderator remove it if it was inappropriate). I certainly don't mean to reply in a way that is either hectoring or "uncivil" as you imply.
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Re: Low impact removal of big trees?

Postby RichardKing » Thu Jun 14, 2012 2:27 pm

Well Oldclaypaws, coppicing may well produce a type of biodiversity consistent with a coppiced environment,
but then an old growth environment will produce its own type.
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Re: Low impact removal of big trees?

Postby carlight » Thu Jun 14, 2012 3:41 pm

Am glad to hear that you are going to take some time over your plans for your woods , greypaws .
May i also point out that the original question did ask "is there a need for thinning" . Thus i found the long post not only relevant ,but pleasingly easy to read ,and most refreshing-it seemed to manifest my own innate feelings towards excessive bio management.
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