What are the shallowest rooted trees and shrubs that can planted so they can be removed at a later date if necessary?

Most riparian species.

Most riparian tree and shrub species tend to have shallow root systems and include such species as willow, cottonwood, silver maple and green ash. However, any tree species growing over a shallow water table will tend to have a shallow root system. On the other hand, it is important to remember that root systems of most woody plants will also go as deep in the soil profile as good aeration will allow.

Along many of our deeply incised streams the water table has been dropped to averages of more than 3-5 feet during the growing season allowing deeper rooting. As a result upland as well as riparian species can be successfully planted. This question has been asked by people who consider converting the buffer back to row crops after the CRP contract has expired.