Compared to their larger growing cousins, Japanese maples and their other Asian relatives have very modest and completely non-aggressive root systems. But like any tree, as they mature there will be lots of roots present under the soil surface. And these roots tend to be extremely sensitive to any disturbance - injuring them in any manner can lead to some very serious problems.

I typically suggest designing and then planting the surrounding bed at the same time as you plant the tree, thereby reducing the potential for damage later on. And if you can limit your plant selection to low shrubs, groundcovers or spreading perennials that do not require division - plants that require minimal attention or cultivation once established - your maple will be very happy.