[Talk-at] [mechanical édit] change depreciated tag wood=* by leaf_cycle=*/leaf_type=*

[Friedrich Volkmann]

On 07.09.22 12:18, Marc_marc via Talk-at wrote:
> I propose to make a  a mechanical édit (=edit without human review of 
> individual objets) in Austria to replace the deprecated wood=* tag
> 
> the doc of the tag https://wiki.openstreetmap.org/wiki/Key%3Awood
> 
> there are currently 323 objects and 3 values of which here are
> the conversions:
> wood=coniferous -> leaf_type=needleleaved
> wood=deciduous -> leaf_cycle=deciduous
> wood=mixed -> leaf_type=mixed

That edit leads to information loss, because the transition is a non-injective 
function.

The leaf_type/leaf_cycle proposal was approved by voting but unfortunately its 
content was flawed. It didn't take into account palms and larches. While palms 
only matter for the tagging of individual trees (type=* subtag), larches 
matter when it comes to landuse=forest and natural=wood.

Woods in our climate are traditionally classified as coniferous (Nadelwald), 
broad-leaved (Laubwald) or mixed (Mischwald). For some reason that I don't 
know, this classification has been mapped to wood=coniferous, wood=deciduous 
and wood=mixed in OSM. But wood=coniferous may include larches (Larix decidua) 
which lose their needles in winter, and wood=deciduous may include the 
evergreen Ilex aquifolium.

Due to Larix, you can't map wood=coniferous to leaf_cycle=evergreen. But you 
also can't map it to leaf_cycle=mixed when you don't know if Larix exists in a 
certain area. Replacing the old tag with the new tags requires local knowledge.

I think you can ignore Ilex, because it is relatively rare.

As wood=decidous is not used for conifers, you can set leaf_type=broadleaved 
on all wood=deciduous.

For mixed woods, leaf_cycle=mixed is a good guess because Larix decidua is 
usually found in higher elevations where broad-leaved trees are rare.

> For objects that already have the new tag, the old tag is simply deleted

That's a very bad idea, because it loses information without providing any 
benefit.

Conclusion:

If you want to do a mechanical edit, add these tags and leave the old tags 
(wood=*, type=*) intact:

wood=coniferous: + leaf_type=needleleaved
wood=deciduous: + leaf_type=broadleaved + leaf_cycle=deciduous
wood=mixed: + leaf_type=mixed + leaf_cycle=mixed

-- 
Friedrich K. Volkmann       http://www.volki.at/
Adr.: Davidgasse 76-80/14/10, 1100 Wien, Austria