[Tagging] natural=????

[Tod Fitch]

I'd like to start adding some vegetation information to an area
in the mountains of Southern California. There are a couple of
situations that I am uncertain of the correct tagging of treeless
areas. For this query though I'll restrict it to areas at or
above timberline.

I believe the wide spread term to describe the ecosystem is
"alpine tundra". Certainly the Wikipedia article on southern
California mountains refers to it that way:

http://en.wikipedia.org/wiki/California_montane_chaparral

And the Wikipedia page regarding alpine tundra affirms it:

http://en.wikipedia.org/wiki/Alpine_tundra

But the closest looking tag I see at
http://wiki.openstreetmap.org/wiki/Key:natural seems to be natural=fell

Fell appears to be a UK centric description for a subset of
alpine tundra: http://en.wikipedia.org/wiki/Fell

There are currently no natural=*alpine* tags and only a handful
natural=tundra, the use of which seems to cover both alpine tundra
(mountains in Colorado) and arctic tundra (northern Canada, etc.)
without a way to distinguish which of the two are meant.

What are the thoughts of extending the natural tag to include:
natural=arctic_tundra, natural=alpine_tundra and, possibly,
natural=antarctic_tundra

With descriptions per Wikipedia:
http://en.wikipedia.org/wiki/Tundra
http://en.wikipedia.org/wiki/Alpine_tundra

Regards,
Tod