There are areas thatI am familiar with, that grew such a dense high level canopy, that all the mid-level trees died out. There is not a single sapling or seedling growing ANYWHERE....nothing but ferns and dirt. The deer didn't eat the mid-level trees like beavers...they just died out.
The only sapling you will see in that area is an occasional poplar having three trunks over 10 feet long and about six leaves on each trunk total.
The thingsare barely making a living.
The area I speak of is an ancient glaciated region that has only sandy soil, no loam of any kind. An Oak will not grow there unless you bring in the dirt for it. That's whatI referred to before.