My grandfather worked as a lumberjack for a time in the 1950s in Washington State, and the stories he used to tell us were pretty scary. If you consider the fact that you are in mountainous, uneven terrain, usually on foot, cutting down trees which weigh several tons and are subject to root strength, wind direction and speed and degree of lean when you cut them down. They are only somewhat predictable. Once they are felled, they are literally dragged by chains and heavy machinery through the forest, at a pretty good speed, and the moving of the logs is actually where more injuries occur.
Once they are felled, trimmed and loaded onto trucks, imagine driving a truck at high elevation with 40,000 lbs of logs on board on a long semi-truck, down a brand new, narrow, curvy and sometimes unstable roadbed. Accidents are common as are injuries.
If we are talking about lumberjacking in a non-mechanized environment, this is a very dangerous occupation indeed.
First of all, there is the danger from the trees. Although skilled loggers can fell trees in a given direction, this is not fool-proof. When you have lots of people around and huge trees falling, the danger is real. I remember when I was a kid we visited a family friend who had been a logger and was now disabled because of such an accident.
Second, the tools are dangerous. Axes and even chainsaws can easily hurt a person. When you work all day at such a tiring job, you stop being 100% careful. When you are not careful, these tools can really be dangerous.