What are your plans for the property and how many acres do you have?
I ask this because there is good birch, which is white and yellow, and then there is Gray Birch which is almost utterly useless...even for
firewood and there aren't too many trees that suck at being firewood. To me they look like gray birch, which tends to fill in unused fields really quickly and is considered a weed since they grow up fast, do not get big in diameter, and are super prone to rot. They contain no BTU's for firewood either.
Still if you have plenty of
land, then you could justify their existence. I mean if they occupy say 1 acre and you have 30, it may be worth keeping, but if you only have 5, and you have an 1 acre of them I would think there is more beneficial things to do with that acre then grow birch saplings. Out of
experience, I have a few acres of them myself and I keep them only because they are on ledge rock (thin soil) and my plan is someday to mow them down as mulch and plant wild blueberries atop of them since we can grow blueberries wildly here.
You could build a
rocket stove and use them for firewood to heat your home
You could
fence them in and let goats (or sheep) graze them down to non existence
They could be mown with a sickle bar mower and thrown into a
hugel
They could be tilled under and used as eventual nitrogen
White and Yellow Birch have far more uses, but on the edge of a field they tend to get "limby" that is they stretch their limbs out towards the field and are usually short and stubby. Naturally the gray birch stand will self prune itself, but like anything with forestry, your talking many years out. In the intervening yours you will not even be able to walk in the stand; like lambs, they look cute and cuddly now, but that will soon change as they grow bigger!
Your first step is figuring out just what they are.