Yeah, I'm pretty sure they don't mow under it, it's not exactly tame. There are more trees here than the grass across the street, but it doesn't fit to be a wood either because it doesn't make a "canopy", which I believe was the words of the wiki. Judging by that I feel it is safe to leave as scrub, even though the primary land cover is grass, but does surface=grass work for tagging things other than roads/lines?