Or another idea: Fallen trees are treated (optional) as real objects with a health bar. Fallen trees can now be destroyed by explosives, zeus or other things (I see a chain saw mod incoming...).

Depends what you mean by "way". You can check damage in namedProperties of the object. If it's "tree" and object is already dead, it has fallen. You can "remove" it by hiding it.
But admittedly detecting it in a running mission is difficult without loops.

I mean it has to be something practical. The best thing would be if a falling tree fired an event that contained its id so you could do whatever you wanted with it (removing it or even unfalling it), either immediately, or store it in a list to deal with later.

The same thing would be really useful with vehicle tire marks.

Both fallen trees, and vehicle tire marks accumulate during long games until they become a problem. In the case of tire marks, it eventually causes performance issues and visual glitches. In the case of trees, you just can't see anything.

Aren't vehicle tire marks local and disappear as soon as camera goes away? Unless its different scripted tire marks.

As for the trees, perhaps another mission event handler can be added here that would include simpler objects like trees: ObjectKilled (compared to EntityKilled). Maybe model's type property (bush, tree, church - these ones) can be sent into arguments of EH so it can be filtered by script quickly.

Speaking of model type property, is there a way to get it through scripting command at all? Maybe add it into getModelInfo too?

Aren't vehicle tire marks local and disappear as soon as camera goes away? Unless its different scripted tire marks.

They should go away, but they actually (at least some of them) keep piling up, and eventually cause problems the longer the game goes on.

@FlyingSaucer @doodle jump They should go away, but they really (at least some of them) keep stacking up and eventually cause difficulties as the game progresses.