Magnolia s can be pruned as needed to build structural soundness. However, heavy accumulations of ice can wreak havoc even on a structurally sound tree. If there are broken limbs now, prune to a clean cut. Then wait until after bloom, to prune any more branches. I would not recommend limbing up a magnolia.
Magnolias constantly shed old leaves, and exposed roots are also a problem.
Allow the branches to go to the ground line. The Arkansas Cooperative Extension Service offers its programs to all eligible persons regardless of race, color, national origin, religion, gender, age, disability, marital or veteran status, or any other legally protected status, and is an Equal Opportunity Employer. The mention of any commercial product in this web site does not imply its endorsement by the University of Arkansas Cooperative Extension Service over other products not named, nor does the omission imply that they are not satisfactory.