Ability: Restoring (Dead) trees back to full health with autocast enabled?

I'm in the middle of creating a map and have created a neutral critter unit that wanders around the entire map by flying and is supposed to resurrect dead trees but I cant figure out how to do this. None of the abilities that are present allow me to even select a tree to target it. Even after I specify it's target as "Tree, Alive, Dead" it still wont let me select a tree on the map.

If I try changing it to a "repair" ability and only have the allowed targets as "Tree, Alive, Dead" it still says "target is not mechanical or a structure" and when I target a structure it says "Target is not a tree"

how the heck can I get around this problem, It's very annoying and almost seems like the mechanics of the ability cant be modified even if you try to change it. ie it still requires me to select some kind of mechanical or building unit even though i have removed those parameters.|||I've had terrible luck getting spells to target destructables directly.

Here are 2 options depending on your goals.

If you just want destructables to come back on your map at a slow and steady rate, set a slow repeating timer that picks a random destructable and increase its life.

If you really want that flying sheep or whatever doing the resurrections, then every few seconds get all the destructables in an area around your flying sheep and set their life to 100. You can even generate a cute dummy effect at the site of each tree you resurrect.