If all you want is "dappled lighting" you can add some lights with a dapple filter of your own creation. Sometimes with 3D apps you just have to "fake it" rather than expect the virtual world to behave like the real one. As far as RAM goes, I let Bryce5 play with 600MBs, but then I have 896 MB installed. The technique I was showing you at least allows you to use 2D faces for the "deep" part and real trees, that may dapple light, in the foreground. Believe it or not light does pass through the transparent parts of the 2D faces and casts shadows.