In examining vintage bows you will find that many old time bowyers used a very thin backing on their self bows. Sometimes this backing was more of a thick veneer that followed the undulations of the wood rather than the more common silk, linen, and similar that would have been used for that application. The latter were obviously not designed to induced reflex or store energy. In fact, neither were the thin wooden backings. Rather, they helped insure that the bow wouldn't blow apart.
Some bowyers (including myself) have abandoned the traditional backings used for that purpose, which can be tricky to apply effectively, and have adopted such things as brown paper bag material. Now, that may sound stupid at first, but I'm not suggesting literally using a brown paper bag, but rather the heavy brown paper that comes in rolls for art and packing purposes. It can be cut to the length of the bow and eliminate splicing. And here's the great part...it is nothing more than interlocking wood fibers, which simply put is a veneer thin, ready-make growth ring. When saturated in glue (I use TiteBondIII) and applied correctly, it adds a safe, tough, and and attractive backing that will following the undulations of the bow's back.
I'm not sure how heavy your bow is, but I've used paper backings on longbows up to 55#. I can't really tell from the picture exactly what's going on, but if you just clipped through the growth ring, a backing like I described should suffice if properly applied. If you actually have saw marks, you can fill these in with superglue or something similar, sand smooth, and then apply the backing right over it. Hope this helps!