This is an easy way to collect one of natures best fire lighters, but it requires you to find large trees in relatively exposed locations
as you can see this is a tall birch in just such a location
what tends to happen is the prevailing winds whip up little pieces of bark which then get pushed round the tree onto the leeward side. These are known as 'Ribbons' of birch bark.
and if you leave it for a couple of months you can get vast amounts of birch bark for virtually no effort, just pick it all off the leeward side of the tree..
Although trees in such perfect placements are hard to find, when you do get them you can fill your tinder pouch with birch bark ribbons easily and quickly.