Nature uses animals to cause some forms of disruption such as trampling and rooting this tends to be localized instead of an "all over" disruption.
Nature also uses wind,
water and fire to create disruptions, wind blows down
trees, the
root system leaves a pocket of freshly mixed soil horizons, it will also move exposed soils (dust storms).
Water erodes already laid down soils and redeposit the material at the lowest point and where the water slows down.
Fire burns off (exposes) soils to the wind and water, some seeds require fire to be able to germinate.
Tilling tends to be far more "large scale" disruption than anything nature does, this is why it can be devastating to soil life and soil health.
Tilling however can be judiciously done and when it is performed this way, it can actually be a good thing for the soil.
Tilling can break up compaction layers, adding needed air and water channels, it can blend horizons, allowing for more topsoil to be created via the microbiome.
As the tilling is done, improvements to the soil in the form of amendments such as
compost or other organic materials are being put into the soil below the surface level.
However, turning over huge expanses of soil exposes those microorganisms living in the "treated" depth to UV light and UV light is deadly to those organisms, hence they die from sun burn.
This means that every time you till soil, you will need to replenish that soil with the missing microorganisms (since you killed them off).
The trick is to be aware of what your soil needs help with and which method of giving that help is the best, at that time.
One time tilling is a very good method of raising the humus levels of soil and it can be used to break up compaction layers at the same time.
This type of tilling is done in a single pass, then the soil is planted so the soil will be covered as soon as possible.
Redhawk