Legal Question in Real Estate Law in California

I doubt that this question has ever been decided by the courts, at least not in a published appellate case. Technically, the trimmed limbs "belong" to you, since they came from your tree, but I believe most judges would think that tossing the clippings back to your side after pruning them off was a bit in excess of his rights (to remove the trespass) and unnecessary to "protect" yours (to have "your property" returned to you). I hope you can resolve this amicably.