For me, it doesn't make any sense. I know farming speed is like 3-4 times faster than real life, so I expected erosion worked at the same speed on average... but it doesn't. Assuming trees reach over 2 meters (7 ft) in their adult shape, you need a really fast tree to grow from seedling to adult in one year, or even in 2 years. My current char has survived for 3 months, and tree growth, specially in some places like the ones without any grass or trees near them, have a lot of trees. So, if the growth speed keeps the same, Ithe places I will be able to reach without an axe will decrease significantly after a year, and after 2 I probably won't be able to go anywhere without an axe.