I’m starting this thread to discuss a issue I keep running into. Around me in the Welsh valleys and especially on many of the commons. There are large areas covered in dense waist height bracken. I’ve included the photo below I pulled from google search to give a visual of what i’m talking about.
From my understanding `natural=grassland` is used to represent areas dominated by grasses and non-woody plants. I feel ferns such as bracken fall into this category better than any other land covering tag. However I feel that this betrays the intent of a grassland tag as I interpret grassland as being open and easy to navigate where fernland not easy at all.
I’ve seen and used a subtag of grassland grassland=bracken or maybe grassland=fernland would be better.
I somewhat agree but I always interpreted scrub is to be used for woody bushes and dwarf tree. I’ve gone of the rule that if it wilts in winter then it can’t be scrub but maybe I’m just being too particular about it. As a obstruction scrub does fit well.
I agree. I would go with natural=grassland for the main feature tag for a fern dominated landscape. Grasslands are not limited to grasses only. They also include many other forbs, and ferns fall into that category. An attribute tag or subtag further specifying fern/bracken dominance also seems reasonable.
This varies. Some grasses can grow to around two meters tall under the right conditions. Navigating through tall grass like that can be a bit of a challenge.
If the trees were a little more dense in your photo I’d be leaning towards natural=scrub, but natural=grassland grassland=bracken seems appropriate to me. In this case I’d map the bracken as a separate area within the wider grassland area, so the tagging for it can easily be changed in future regardless. At least in North West England, bracken areas are fairly slow-moving so stay consistent across years and can be correctly mapped as a separate area.
I have just discovered there is a botanical definition on wikipedia which may be of use. oversimplified it defines shrubland as shrubs over 2m tall and heathland under 2m tall. but I still don’t agree either either for bracken since its got a soft grass-like structure rather than a woody structure. although it would be nice to have a 1st level tag for land coverings like ferns i think natural=grassland grassland=bracken or grassland=fernsis good enough for now as its unique enough to easily be replaced in the future
Cos that’s what I understand the term to mean on these islands? Grasses, bracken, heather, gorse… basically what you get on uncultivated land that is too exposed (or sheep-munched) to revert to scrub or woodland.
Is that not what most people regard as heath?
If there’s only grass and wildflowers I’d probably call it a ‘meadow’.
I don’t want to be the “read the wiki!!!1!” type as the wiki is not gospel, however the very first line for natural=heath states that this tag is to be used for areas with “open, low-growing woody vegetation, often dominated by plants of the Ericaceae (Heather)”.
Then we have natural=grassland which are, also the first line, “areas where the vegetation is dominated by grasses (Poaceae) and other herbaceous (non-woody) plants, excluding cultivated areas and wetlands.”
It’s already established (even in just this thread) that natural=grassland is not exclusive to grasses.
The Wildlife Trusts page on Bracken does note that it can be present in both grassland and heathland (same for gorse), but from my understanding we are mapping what is dominant. Heath on imagery here in Wales tends to appear much darker and purpler compared to grassland, which really helps differentiate (this has also been underpinned by surveys/local knowledge of users where I’ve been mapping heaths - personally I feel like this is a good barometer between natural=heath and natural=grassland).
The fake heaths that cover Wales encompass anything and everything that’s vaguely upland without considering any of the features within, which is why a simple retagging exercise to grassland (already been done by another mapper and self-reverted years ago) also doesn’t work, they’ve got to be redrawn properly with attention to detail and in small enough areas that retagging is easy if needed.
Ferns are not grasses, you are correct but ferns are a herbaceous plant. And to quote the wiki for natural=grasslandagain “dominated by grasses (Poaceae) and other herbaceous (non-woody) plants”.
Everything, because the OSM wiki defines what a certain set of words in OSM tags (such as natural=grassland) is actually agreed upon to be interpreted as by editors and renderers. That’s how this has always worked. There can’t be tagging consensus without a set of definitions of tags somewhere.
If the wiki defines natural=grassland as an area covered in nothing but jellyfish, then it should only be used for such areas, even if that seems absurd to people and doesn’t seem to match what they would expect the term ‘grassland’ to imply. Obviously it helps if the tag grassland corresponds to what most people think of as ‘grassland’, but it can’t always match every expert or lay-person’s conceptions of the terms perfectly.
Look sorry, but if the wiki is dubiously written and/or flat out wrong, then it’s silly to compound the problem by slavishly following what it says.
Who edited the wiki pages? And what did they know about botany? just amend the wiki to say something better!
(I can’t edit it myself at the moment, i got locked out if my account and have never gotten around to rescueing it yet…)
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The OSM wiki is full of artbitrary blether 
just amend the wiki to say something better!