Hey DV; if you take a plane (kind of elongated in front of the tree over the whole length), make it fake semitransparent by a default shader + a playable power fractal with small values, then apply a reflective shader to it, perhaps you could get some sort of shimmering..... the reflection would only be at the 'white areas', the 'black areas' you would see through. Just a theory.....
---Dune