I have came across a similar issue where areas of mainly grass, but with
some gorse bushes, on chalk downland had been changed to natural=heath,
when I contacted the mapper about it he said something along the lines
of, "well I've seen it done like that elsewhere"
David
------ Original Message ------
From: "SK53" <sk53....@gmail.com>
To: "Talk-GB@openstreetmap.org" <talk-gb@openstreetmap.org>
Sent: 09/01/2017 11:53:51
Subject: [Talk-GB] natural=heath
Somehow I have been oblivious to the fact that large numbers of
polygons tagged natural=heath have been added over the past few months
to OSM.
I only noticed these when looking at old traces on the new GPX trace
overlay. Specifically I noticed them on the Snowdon range extending
beyond Moel Eilio.
I have now reviewed my photographs taken in 2010 for the countryside
extending N of Moel Eilio to the pass between Foel Goch and Moel
Cynghorion. As it was a beautiful day the photos also provide valuable
interpretive evidence not only for the rest of the Snowdon range, but
for the Northern Glyders, Mynydd Mawr and the Nantlle Ridge.
Both in detail and in long view the vast bulk of this countryside is
unimproved grassland, which is why it is used for sheep farming and not
grouse moors. There appears to be a small patch of heather moorland
beyond the forestry to the N of Moel Eiio, and possibly a patch in one
of the valleys to the E.
In addition to reviewing my own photos I have also checked the same
areas against the Phase 1 habitat survey carried out by the Countryside
Commission of Wales roughly between 1980-1995. This also shows the vast
bulk of the area as being acid grassland, albeit with some small areas
of mosaic grassland and heath. Unfortunately I cannot show this
analysis because I obtained the data under an distinctly non-open
licence and need explicit permission from Natural Resources Wales to
publish the data.
This is not to say that the use of tag natural=heath is wrong. Many of
the areas which have recently been mapped as natural=heath can also be
described as moorland or rough grazing depending on context (upland or
coastal).
The more usual use of heath, certainly within communities of
naturalists, conservationists and ecologists, is for habitats dominated
by ericaceous (members of the heather family) shrubs & sub-shrubs:
i.e., heather, bell heather, heaths, bilberry, crowberry etc.
The phase 1 habitat manual (phase 1 is the basic ecological survey
technique developed by the Joint Nature Conservation Committee, JNCC)
states:
"Heathland includes vegetation dominated by ericoids or dwarf gorse
species, as well as 'heaths' dominated by lichens and bryophytes, dwarf
forbs, Carex bigelowii or Juncus trifidus." (p. 41, 2010 revision)"
Personally, I would prefer that we stick to a definition similar to
this one. There is not likely to an entirely straightforward
correspondence with Phase 1 as some upland heather moorland may get
mapped in Phase 1 onto other habitats, particularly if underlain by
large quantities of peat.
The reasons for this are:
Habitats are different. Habitats as different as these should be tagged
differently. Upland and coastal unimproved grasslands are very
different habitats to heather moorland and very very different from
rare lowland heaths. Just the range of birds one encounters will be
different. On the former I expect to see Meadow Pipits, Wheatears and
no Red Grouse. Lowland heaths in Southern England are habitats for
quite rare birds: Nightjars, Woodlarks, Dartford Warblers.
Terrain underfoot is different. There is a massive difference between
walking though knee-deep heather in places like the Rhinogs or the Mull
of Kintyre, the lovely turf on the ridges N of Snowdon, or tussocky
coastal grassland. We should be capturing such things.
Visual differences. The image of the country is different. Most
apparent when heather is in bloom.Landuse differences. Most obviously
sheep grazing versus grouse moor, although sheep may still be
encountered on the latter.
Obscuring rare natural areas. Genuine lowland heath is a rare
phenomenon in Britain and requires great conservation effort. Extension
of the natural=heath tag to cover other things means that identifying
these special areas using OSM will not be possible.
I reviewing the extent of current use of natural=heath I may already be
too late in preventing an extension of its meaning to cover more or
less all non-intensively farmed areas which aren't wooded.
Notwithstanding this I would like to canvas views from other mappers.
If the current usage of the tag is deemed to be the suitable one then
we need to develop additional tags which allow the recognition of all
the features I mention above.
Regards,
Jerry
_______________________________________________
Talk-GB mailing list
Talk-GB@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk-gb
