insert into control.lua between line 449 and 450 (right after "if r then"):
if r == 'dead-tree' then
tile_type = surface.get_tile(e.position).name
if string.find(tile_type, "sand") or string.find(tile_type, "desert") then r = 'dead-tree-desert'
else r = 'dead-grey-trunk'
end
end
Haven't managed to get the "desert" path to trigger yet, so it's not fully tested.