While your fruit trees are growing up, it is very helpful to also plant some short term protection for them. Young fruit trees appreciate protection from heavy rain, frost, wind and too much sun. The idea is to create a supportive micro climate around them. Dappled shading in summer means a LOT less watering is needed and the taller plants shelter the young trees from the worst of rain, wind and frost.
Pigeon peas do that job really well in this area. They only live for about 5 years and by then the fruit trees are established. They grow very quickly to a protective height of about 2.5 metres. They have a canopy that allows filtered light in which is enough for young trees to keep thriving. They don’t out compete other trees with their roots. They are nitrogen fixers which is good for the soil for young fruit trees. And when they come down they aren’t heavy or destructive (black wattle!!).
As a bonus, pigeon peas flower over winter which is excellent for the bees and they produce edible bean pods. These pods aren’t really worth the effort to pick and shell, but you could if you wanted. Besides, the parrots love them. Though encouraging parrots may not be ideal depending on your garden! If that’s the case, any quick growing, short lived, nitrogen fixing bush/tree will do the job. We have a lot of acacias that might be suitable. But maybe not black wattle. It’s a hardwood which means that it is dense and heavy. When it falls over it can mash a hills hoist. I may be speaking from experience. You don’t want a baby fruit tree to be hit like that.