I couldn't tell for sure from your pictures, but are the trees all/mostly softwoods? A problem I had with laying out a couple of my trails was being deceived by apparent maple saplings that turned out to be coppice wood from much larger stumps. It was easy to take down the sprouts (up to 4 or 5 inches in diameter), but the underlying stump was for a much, much larger tree...plus, there was then no leverage to push on it.
Softwood species like spruce, fir and pine don't usually coppice, so small trees have smaller stumps and root systems. Plus, they tend to be shallower-rooted than maple, birch and beech, so are easier to push over.
I like a multitude of trails so I can vary my walks (but I don't have a lake shore to distract me!).
Bob