The Amazon river
The 4 layers have different sun light levels and the shrub level has the least sun light because it is under all the big long trees above it causing for there to be not so much light.
Also the under canopy is not quite so bad because it is still under tree so that means that some of the sun light can still not get to it, however it is a bit higher than the shrub level so it dose get more light in that the shrub level but only one quarter.
Next is the canopy, the canopy is just above the trees so it gets a lot more sun light than the other two below. But still it’s not at the top, there is still some things in the way of the sunlight. Finally there’s the emergent layer and this is at the very top of them all. It gets all the sunlight and there’s nothing in its way no trees either so it is the complete opposite of the shrub layer, although the shrub area dose have a bit of sun light.
It can take 10 minutes for a rain drop to fall from the Emergent layer all the way down to the shrub level.