Attached Link: http://o.ffrench.free.fr

The answer is... no. I've tested it with grass, not trees, around 1000 grass blades of 8 polygons each... it does not work very well. When you drop to ground, half of them go underneath the terrain. The only solution I found was to select around 100 grass blades at a time and then drop them to ground. Make sure that your ground is not locked before proceeding.