Answer:
govern the federal capital and federal areas
Step-by-step explanation:
The clause granted the Feds with the power to Prevent a 'derogation of values' from a certain area.
This is related to the creation of creation of the National Park Service (NPS) Because the BPS is established to conserve the scenery and the natural and historic objects on all government owned land
This basically prevent individuals and corporations from exploitation the resources in NPS territory without the permission from the government. (hence protecting them from the derogation of value).