I find the idea of “nurse trees” interesting. From Wikipedia:

A nurse tree is a larger, faster-growing tree that shelters a smaller, slower-growing tree or plant. The nurse tree can provide shade, shelter from wind, or protection from animals who would feed on the smaller plant.

Eventually the younger plant outcompetes the older one, and the older one dies, or I suppose it can be cut down by humans. I am thinking about how to apply these ecological concepts to give a helping hand in more urban areas. In my professional work on stormwater management, we often dig up urban soils and replace them with a manufactured soil mix that is more permeable to water and better for plant growth. But all that digging and trucking and waste disposal has a cost and an environmental impact, when we are doing all this to try to help downstream water quality. Maybe we can use carefully chosen trees or plants early on to loosen and add organic matter to the urban soils, then come back a year or two later and plant the trees and plants that we want for the long term. Even better if there is some plant mix where the first phase is faster growing, but then gradually gets out-competed by the second phase, just like the nurse tree concept described above.