When I lived on a farm in wales, we would occasionally discover in our fields something called bog oak. This was trunks of oak placed in the ground by ancient farmers to drain a field. Over the centuries this had become semi-fossilized and in the process had become very strong. From high quality bog oak, it is possible to make wooden rings as strong as metal. Our bog oak was not so good (I tried) but certainly good enough for super strong dowels and suchlike.