N.H. Rev. Stat. Ann. § 231:152

Whenever any trees or brush cut along the highway are disposed of by burning, the cut trees or brush shall be removed a safe distance from any adjoining woodland or from any tree or hedge designated or desirable for preservation, and such burning shall be done with the permission of the forest fire warden. All trees or brush thus cut from within the limits of the highway shall be disposed of within 30 days from the cutting thereof.