I know others have weighed in already but I just had a few additional suggestions. Using what you already have you can get more use out of one tree (or one low poly model) by changing the colors, scaling it significantly smaller/larger and rotating it as well as creating areas that have more of one of these variations with a few others scattered around. So for example color: light green, green, dark green. Scale, very small almost sapling, medium to normal and overgrown (only have several of these. Also tipping some trees slightly and even maybe laying some down as if they were recently cut. I see a building in the map so it stands to imagination that they might need wood for a fire or perhaps that’s how they built that fence. The same advice goes for the rocks but in addition with the rocks you can combine multiple rocks to make jagged boulders, a cave entrance, a rock wall (as opposed to fencing) a water well, many many possibilities. At the end of the day your map is amazing, but feel free to sit back and after a good look just play on it. Run around and use your imagination and have fun. As you play you’ll start to think, hey I could put this here, or I wonder how this would look, or oh I should have done this too. I hope you keep building because this is truly an amazing start!!