[Talk-GB] "Lines of Trees" along river banks etc.

[sk53.osm]

I don't think these are hedgerows at all. They are really relict river
gallery woodland (usually *Salicion albae,*
NVC<http://en.wikipedia.org/wiki/Woodland_and_scrub_communities_in_the_British_National_Vegetation_Classification_system>W6)
and I would expect are mainly Willows with the odd Poplar and Alder.

A photo example (and a location) might help.

Typical components along the Trent (Notts & Derbys) and Thames (Berks &
Bucks)  will be:

   - planted trees, usually hybrid Poplar and White Willow, but some real
   oddities
   - Crack Willow and Alder as standard trees
   - pollarded trees, mainly Crack Willow
   - shrubby trees, predominantly Osier and Grey Willow, but some Almond &
   Purple Willow
   - occasionally dense scrub with Hawthorn and Elder

The willows nearly always are self-set. Any willow twig broken off in a
flood is capable of regenerating (for Crack Willow and Native Black Poplar
this is the usual means of propagation), provided there is enough moisture.
This means that river banks are naturally always getting new additions, and
that clearance of willow scrub is a never ending task. However, the zone
where this happens is quite narrow, depending of height of flood waters and
maintaining the relevant moisture levels.

I don't know much about palatability of willows to livestock, but suspect
they are not very tasty. When fields have grazing next to a river, usually
cattle will have made a few gaps to get at the water, but my impression is
that they don't graze on willows, although sheep probably do.

It may be useful to show that a water body is tree-lined. I personally use
tree_lined=yes on tree-lined roads (more as a place holder), but there is
also natural=row_of_trees. You might want left and right. For the scrub
willow thickets I think natural=scrub is the right tag, even if you choose
to put it on a way (these will be NVC W1-W3, with W1 being the commonest).

Regards,

Jerry


On Wed, Aug 28, 2013 at 11:15 PM, Dudley Ibbett <dudleyibbett at hotmail.com>wrote:

> Hi
>
> I was wondering if anyone has been mapping these?   Quite often I come
> across streams and rivers where there are dense lines of trees along the
> river banks.  Occasional I find lines of trees which seem to be remnant
> hedgerows where the shrubs have been removed.
>
> Looking on line it would seem that these are a hedgerow type.
>
>
> http://www.hedgelink.org.uk/images/bap/key%20to%20hedgerow%20types%20bigger.jpg
>
>
> https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69285/pb11951-hedgerow-survey-handbook-070314.pdf
>
> This would perhaps suggest they should be marked as ways with
> barrier=hedge and hedge=line_of_trees or perhaps just the latter.
>
> An alternative might be to use natural=tree_row which is defined in the
> wiki but the examples seem more to related to trees that have been planted
> at regular intervals and where there isn't generally an overlap in the
> canopy.  I have used this a few times but I'm not convinced it is the right
> way to tag this feature given that it seems they are a type of hedgerow.
>
> This may be something for the tagging email group but these a quite common
> features in the UK so I thought it would be good to ask here first.
>
> Many Thanks
>
> Dudley
>
>
>
>
>
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>
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