Sorry for the late response, your changeset comment must have gotten buried in my emails.

The reason I changed these to sand is due to a desert being an area that receives little rainfall rather than being a specific landscape surface, the surface of the Mojave being sand. For comparison, a forest could be made up of several components - wood, scrub, water, bare rock, etc - whereas natural wood is just the trees themselves. By this logic, a desert could be a whole region with a mix of sand, heath, scrub, water, bare rock, scree, etc., or could simply be a very green heath-covered landscape like Northern Nevada is or one covered in permanent ice like Antarctica.

Another reason I tag these areas as sand is due to heath and scrub generally referring to much greener areas like the aforementioned northern region of Nevada, such as the Great Basin Desert. The Mojave Desert is covered in heath/scrub, however it's arguably more sand/gravel than vegetation. This scheme isn't entirely my idea though, and I've based it off how part of the Sonoran Desert is mapped around where California/Arizona/Baja California/Sonora meet.

Some of what I'm saying contradicts how I retagged these features, especially with the scrub overlapping the sand around Cima (though it could probably be easily fixed with some multipolygon-ing or realignments of the areas), and by my belief that a valley isn't really a landscape as much as it a geographical feature like a mountain would be and could be any surface. However, my intention was that this would be somewhat of a temporary solution for the Mojave Desert to be mapped, with the hopes that someone with a little more time than me could come and detail this area or if I just did it myself and separated the valleys and sand into their own relations, like I had started doing to some areas like the Amargosa Desert. It does seem a little redundant to have to re-map some areas that are already covered by natural=* polygons rather than simply retagging them like I did, but I do know that it could be an issue.