Is there a simple explanation how you created the animation of the leaves?
The leaves in the tree and the flying leaves are actually two separate things.
The tree leaves are created with a mesh and dupliverts (mesh taken from the tree and modified). When the explosion comes, the leaves hide and a particle emitter (with dupliverts on) creates flying leaves (with a z-force applied). I havent found a proper way to stop the leaves when they hit the ground, I use particle deflecting but the leaves tend to pass through the ground
Perhaps I could make a tutorial when I get access to the .blend. Never made one. Won’t probably be a video tutorial, though (dont have a microphone and nobody would understand my english anyway :))