What is bare ground?
Bare ground refers to an area where there is no or little ground cover such as grass. The problem is that the area does not get enough sunlight or the ground cover simply cannot compete with a tree or trees.
Why is bare ground a problem?
Bare ground is a problem because the soil wets up quickly and drys out quickly. Ground covers results in the soil wetting up slower and drying out slowly. This can mitigate the shrinking and swelling of the soil which reduces the distress caused by expansive soil.
How do you solve the problem?
In some cases, you may be able to get monkey grass to grow. There are many varieties. Be sure to use a variety that is shade tolerant.
If all fails, is there a fail-safe remedy?
Yes: if you can not get a shade tolerant monkey grass to grow, cover the bare ground area with much. The mulch will act as a ground cover. The mulch slows down water intrusion into the soil and evaporation out of the soil.
The only downside
The only downside is that the mulch will have to be applied every year if not more often.