If you have an area that cannot grow trees, due to altitude, inadequate groundwater, or having exposed rock rather than soil (as with many mountaintops), then, in what sense is it a managed forest? I am not talking about areas that are temporarily treeless due to the trees having been harvested.
I am talking about how "landuse=forest" as a tag has come to imply the semantic of "managed forest." I'm not saying this is not ALSO tangled up with "usually implies a landcover of trees" -- it IS tangled up exactly like that. We agree "harvested of trees, and so treeless" is still OK to call "landuse=forest." Why? Because we agree that the area so denoted with that tag is "a managed forest."
Additionally, if an area "above the treeline" which will never grow trees is ALSO part of the inside of a polygon of "managed forest" it, too, should continue to remain "landuse=forest" for exactly the same reason: it is an area within managed forest. Perhaps it is also roadless and perhaps it is also the even higher-protected class of wilderness -- OK, that's fine, but we frequently (and correctly, I argue) add wilderness areas as "overlay polygons" within landuse=forest areas without confusion. And that's correct, and even mapnik renders these in a certain way that can be seen (NR over dark green with trees).
What many (all?) seem to agree on is that landcover could very well be improved. Yes, in both use of the tag AND in rendering support!
What some seem to disagree on is that "landuse=forest" is the correct tag for areas which are "managed forest land, whether with or without trees." In my opinion, it means exactly that, as that is how it seems to be extensively, if not exclusively used. At least in the USA where my (wider) focus is.
Then, Clifford Snow and Martin Koppenhoefer get into it:
2013/5/12 Clifford Snow <<mailto:cliff...@snowandsnow.us>cliff...@snowandsnow.us>For administrative purposes and area is designated a National Forest. In practice parts of the National Forest have no trees. Show nature=* make sense if we want to show what occupies the land. National Forest boundaries should be in OSM,
Martin replies:
yes, but not as forests but as kind of protected area.
A "landuse=forest" truly, logically and de facto is "mapped" (in the logical sense) as a "forest (national) which is a protected area." Tags, including:
landuse=forest, boundary=national_park, boundary:type=protected_area, protect_class=6, protection_title=National Forest, ownership=national and name=Name of Forest
as I mention in my previous post exactly capture all of these semantics, and properly. Additionally, wilderness areas and THEIR tags (again, in my previous post) capture THOSE semantics. There seem to be no problems with these, except a complaint that some people don't like large blocks of green represented by mapnik's interpretation of landuse=forest rendering as "dark green with tree icons." However, I still maintain that the landuse=forest tag is accurate as it is used, and if that rendering is not to your liking, please file a bug with the trac system of mapnik. We are using the tag "landuse=forest" to denote national forests, not to mean anything particular regarding the landcover within them. The word "use" (in landuse) strongly implies this. The distinction landCOVER (from landUSE) is not lost on me, nor should it be on anybody else.
Would I like to see more extensive use of the landcover tag with mapnik/standard rendering support -- perhaps even with fancy halftoning algorithms for "80% scrub" or "50% trees"? OF COURSE! But we are only in the early stages of getting there. Let's not dismantle established semantics while we do so.
SteveA California
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