We have been conditioned to believe that life needs sufficient space and resources to reach full potential.
However, recent studies have shown that trees need underground distribution networks that supply water and food to all species via fungi. Trees huddled together improves the productive capacity of the underground network. True, the crowns of the trees are smaller, however the biomass is more dense than a traditional forest, as is biodiversity.
We have started to add mycorrhizal fungi to our tree whips, giving them a little buddy that helps the plants through tough times. The fungal and root network acts as a social security system lifting the whole forest to a healthy and prosperous higher level.
Ref - The Hidden Life Of Trees – Peter Wohlleben