They were bunches of trees, and I think treated as a single object, but I thought that was fine because in reality, any two trees closer together than the width of the chopper was basically a single obstacle, and I thought they did a pretty good job of breaking them up, so you had dense areas with gaps in between, and they seemed fairly naturally shaped (i.e., not rectangular). Its biggest issue was it was billed as being a Longbow sim but it lacked the high-end features. I tried to think of it as more of an AH-64A simulator, and in that I thought it wasn't bad. It even supported multiplayer in the same helo, so you could have a human team of pilot and CP/G in the same bird.

Here's an old video I made of it:

https://youtu.be/RTcpYJeyaCQ