Soil should be viewed as a living ecosystem, it's health underpins plant, animal and fungal growth. It's is commonly understood that:
Soil can be lost through erosion
It takes a long time to create (the quickest estimate is 500 years and the longest tens of thousands of years).
Soils can be poisoned by pollutants or compacted.
An area often overlooked is that soils need to be healthy to function efficiently.
The link below explains the soil ecosystem and it's importance.
When considering planting or when investigating plant health issues, the health of the soil should be a prime consideration.
A common problem is caused by the annual removal of leaves, which if left in situ are a closed loop recycling, providing the tree with vital nutrients, as nature intended.