White spire birch
Can you cut a white spire birch to 1 inch above ground to make a clump?
Hennepin County Minnesota birch clumps
Yes you can if your tree is young. It may not look as nice as a clump that has been developed by a nursery because they have lots to choose from and sell the best. http://arbordayblog.org/landscapedesign/how-to-create-clumps-of-birch-trees/