I am updating the map around the Siffleur Wilderness Area (AB). It is near the junction of Hwy 11and Banff National Park. A wildfire raged in the area about 10 years ago, and I am wondering how to update the vegetation.
The current map data is mainly from Canvec vegetation. On the ground there are standing burned trees with low vegetation (natural=heath, natural=scrub). The update options are:
A) Remove the Canvec vegetation and map the current one with a heath or (most likely) scrub tag.
B) Keep the Canvec vegetation with a life cycle prefix tag (i.e., replace natural=wood by destroyed:natural=wood, or razed:natural=wood) then map the current one with a heath or (most likely) scrub tag.
C) Anything else that the community agrees on.
As large wildfires become more frequent and affect populated or tourist areas like Jasper, I think we should discuss this and find some sort of consensus.
Disclaimer: I am not Canadian. But I am an OSM contributor interested in landcover data.
Staying on topic - in my opinion the correct answer is A.
Keeping old outlines with a lifecycle prefix would make it nearly impossible to further contribute without hiding that portion of the data. At most, this should be moved to OHM.
Veering slightly off topic - I’ve come to believe that because of this and other problems, extensive landcover imports are out of scope of OSM. We wouldn’t create vast areas of topo lines tagged with ele= in OSM, but may add elevation to specific features. In the same sense, I believe that small areas such as woods within urban areas make sense for OSM, but covering the planet and trying to keep that up to date is not worth it.
Instead, data consumers should use datasets like canvec and the US’s NLCD directly, in the same way they might use a DEM (elevation model) to generate hillshade or topo lines.
My view of lifecycle prefixes is that they are for communicating with other mappers, particularly those using aerial imagery, like “the building you might be seeing in aerial has been demolished”, or “that road you might remember being here is no longer in use” - especially if it was added by a person (rather than imported en masse).
If the fire was 10 years ago and it is fairly well known and all the mainstream imageries have been updated, I don’t think we need to keep the imported landcover as destroyed:, because in that case, anyone editing in the area will either know of the fire, or see its effects on imagery. So my suggestion would be for option A.
For more recent fires that aren’t reflected on imagery yet, I would go with option B, to avoid having others undo the change based on (outdated) imagery. Maybe except for very high profile fires like in Jasper urban area, as I think it’s fair to expect anyone interested to have heard that it burned.
Lifecycle prefixes (of former elements) should generally be added with a note=* because else it isn’t clear why the prefix exist at all. Furthermore, the fitting prefix is destroyed:* rather than razed:* because the destruction is neither intentional nor man-made.
Here is what it looks like after updating/replacing Canvec’s vegetation with natural=heath. Since the wildfire was big enough to be named, I also added a name=* tag.
Looks good, but I would delete name=Porcupine Wildfire. The destruction of the forest in the area being caused by said fire doesn’t mean the shrubbery growing back in afterward is named as such. The natural=heath itself has no name.
