Re: [Tagging] knotted willows

2017-02-20 Thread Jerry Clough - OSM
There are problems with this approach.
Many trees are pollarded once in their lifetimes: I'm currently looking out at 
some Beech trees which were probably pollarded 70 years ago, and there's a 
Birch which was pollarded rather crudely 50 years ago in the neighbours garden. 
Ancient pollards can be 500 years old. Re-pollarding a tree which has not been 
managed in this way for a long time is a rather hazardous operation for the 
tree. 
  
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Pollarding - Wikipedia
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If a macrophanerophyte is regularly pollarded then it's probably wrong to call 
it a tree. Most coppiced plants will only be allowed to grow to 5-8 m high and 
the individual stems will rarely be more than 10cm diameter. In Britain Hazel, 
Sallows, and Ash are certainly still coppiced. Oak has been coppiced in the 
past as a source of charcoal. However, like pollarded trees neglected coppice 
stools can grow into large multi-stemmed trees. A typical scenario is a wetland 
site where seedlings of any trees are cut close to ground-level ('coppiced') to 
maintain the wetland habitat: this is a relatively easy intervention and can be 
repeated. However, once tree cover can no longer be halted, or when the ground 
dries out, then the coppice stools will be left to grow of their own accord. In 
most former gravel pits in Britain there are numerous examples of 15m high 
mutli-stemmed Crack Willows which originated in this way.
In general I don't think coppicing is a useful thing to apply to an individual 
tree. Coppicing is more usually a woodland management technique and therefore 
belongs to natural=wood and landuse=forest. A typical woodland form in Britain 
is a wood which is coppice with standards. The understorey (most usually Hazel, 
but in Bradfield Woods it's Ash) is coppiced on a cycle which may be from 5-20 
years. Some trees are always retained and form the canopy. Historically the 
understorey produced firewood, and poles, the standard trees were felled for 
timber. 
For individual trees we might recognise the following properties:
   
   - The tree is a pollard (i.e., has been pollarded at least once fairly early 
in its life)
   - The tree is currently managed by repetitive pollarding
   - The tree is multi-stemmed as a result of growing from a coppice stool
   - The tree is multi-stemmed as a result of growing from the planting of 2 or 
more saplings in a bundle (bundle planting)

Tall Common Limes (Tilia x europea) are often managed by a pollarding-like 
process: side branches are removed, the crown is severely reduced, and the 
trunk is cut short at the top. I'm not sure if this qualifies as a pollard.
Additionally there are other styles of regular pruning. For instance fruit 
trees in the Swiss Mittelland are pruned in a way which is very recognisable, 
so that it is quite easy to identify former orchards where the pruning ceased 
decades ago. The tree is usually pruned to have a leader and four principle 
branches. I suspect this Wikipedia article describes the technique in depth. 
Oaks growing in Dehesa (Cork, Holm and Pyrenean) are pruned in a not dissimilar 
manner, perhaps with 3 main branches, but the centre of the crown is kept 
fairly open. You can see examples here. However I would not choose to add this 
information to OSM: it is safe to assume that trees in Spanish Dehesa and Swiss 
Orchards will generally be manage this way. Quite beside which there are 
something like 37 million oaks in the dehesas of Extremadura.
Jerry


  
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Oeschbergschnitt – Wikipedia
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  From: joost schouppe <joost.schou...@gmail.com>
 To: "Tag discussion, strategy and related tools" <tagging@openstreetmap.org> 
 Sent: Friday, 17 February 2017, 16:26
 Subject: Re: [Tagging] knotted willows
   
Considering that there are several management styles for individual trees, we 
could have something like
tree:managament=pollard
Other values might be none (allowed to grow free), copicce (pruned almost to 
the ground), espalier (pruned into a flat vertical surface), etc.
tree:management:operator=* could then be used to indicate who is keeping the 
tree pruned. 

Maybe tree:pruning_style would be more logical?
2017-02-11 13:34 GMT+01:00 Wolfgang Zenker <wolfg...@lyxys.ka.sub.org>:

Hi,

* joost schouppe <joost.schou...@gmail.com> [170211 09:43]:
> One of the defining small landscape elements in Flanders (and probably many
> rural areas in Europe) is the "knotted willow". I'm not sure if this is the
> right term in English, in Dutch "knotwilg" really is a thing.

> How would you tag such a thing? (I could not find any previous discussions
> anywhere)

> natural=tree
> genus=Salix
> +
> management_style=knotted

> Or something like that?

> Apparently there's

Re: [Tagging] knotted willows

2017-02-17 Thread joost schouppe
Considering that there are several management styles for individual trees,
we could have something like

tree:managament=pollard

Other values might be none (allowed to grow free), copicce (pruned almost
to the ground), espalier (pruned into a flat vertical surface), etc.

tree:management:operator=* could then be used to indicate who is keeping
the tree pruned.

Maybe tree:pruning_style would be more logical?

2017-02-11 13:34 GMT+01:00 Wolfgang Zenker :

> Hi,
>
> * joost schouppe  [170211 09:43]:
> > One of the defining small landscape elements in Flanders (and probably
> many
> > rural areas in Europe) is the "knotted willow". I'm not sure if this is
> the
> > right term in English, in Dutch "knotwilg" really is a thing.
>
> > How would you tag such a thing? (I could not find any previous
> discussions
> > anywhere)
>
> > natural=tree
> > genus=Salix
> > +
> > management_style=knotted
>
> > Or something like that?
>
> > Apparently there's two words in Dutch:
> > - knotwilg: knotted at about 2 meters high
> > - grienden: knotted at a hight of maximum 50 cm
>
> apparently english has words for these managements styles:
> - "knotwilg" would be called "Pollarding"
> - "grienden" would be called "Coppicing"
>
> Wikipedia has pages on both.
>
> Wolfgang
>
> ___
> Tagging mailing list
> Tagging@openstreetmap.org
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>



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Re: [Tagging] knotted willows

2017-02-11 Thread Wolfgang Zenker
Hi,

* joost schouppe  [170211 09:43]:
> One of the defining small landscape elements in Flanders (and probably many
> rural areas in Europe) is the "knotted willow". I'm not sure if this is the
> right term in English, in Dutch "knotwilg" really is a thing.

> How would you tag such a thing? (I could not find any previous discussions
> anywhere)

> natural=tree
> genus=Salix
> +
> management_style=knotted

> Or something like that?

> Apparently there's two words in Dutch:
> - knotwilg: knotted at about 2 meters high
> - grienden: knotted at a hight of maximum 50 cm

apparently english has words for these managements styles:
- "knotwilg" would be called "Pollarding"
- "grienden" would be called "Coppicing"

Wikipedia has pages on both.

Wolfgang

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[Tagging] knotted willows

2017-02-11 Thread joost schouppe
Hi,

One of the defining small landscape elements in Flanders (and probably many
rural areas in Europe) is the "knotted willow". I'm not sure if this is the
right term in English, in Dutch "knotwilg" really is a thing.

How would you tag such a thing? (I could not find any previous discussions
anywhere)

natural=tree
genus=Salix
+
management_style=knotted

Or something like that?

Apparently there's two words in Dutch:
- knotwilg: knotted at about 2 meters high
- grienden: knotted at a hight of maximum 50 cm



-- 
Joost Schouppe
OpenStreetMap  |
Twitter  | LinkedIn
 | Meetup

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