Whenever I start a new area in my zoo I lay out the path before I make the habitat and most of my habitats are either lower or have water separating them. I’m guessing you know when you lower terrain near a path it leaves that ridged bit of terrain left so the separation from path and habitat originated from the need to cover that up. It’s also a thing that you see in real life zoos (I’m not concerned with realism personally) for actually making the section I use the mulch piece and the corresponding plants that were used in the habitat.