Well, yes that is why I want to get involved in some sort of ecological-education movement to try and encourage young people or permeable people to join and sow some more trees!
I've seen that where those trees grow nothing grows around, you're right, so they must have some type of chemical effect in the soil that prevents other plants from growing.
On the bright side, you're right again, the shade that they project is actually the reason why I am doing this, I just love them.
Thanks for the support.