pert, there is a substantial decline from a condition of normal health and vigor of the tree, and its restoration through appropriate and economically reasonable preservation procedures and practices is not advisable; or (iii) It is in danger of falling due to an existing and irreversible condition. (iv) Its continued presence at its existing location interferes with proposed utility services or roadways within or without the subject property, and the only reasonable alternative to the interference is the removal of the tree; or (v) It has no apparent aesthetic value, which will contribute to the appearance and design of the proposed subdivision; or it is not located with reference to other trees or monuments in such a way as to acquire a distinctive significance at the location. 2. Supplemental Authority. In the event the Advisory Agency, in consultation with the City’s Chief Forester, determines pursuant to Subdivision 1.(b) above, that a protected tree may be removed or relocated, the Advisory Agency may: (a) Require relocation elsewhere on the same property where a protected tree has been approved for removal, and where the relocation is economically reasonable and favorable to the survival of the tree. Relocation to a site other than upon the same property may be permitted where there is no available or appropriate location on the property and the owner of the proposed off-site relocation site consents to the placement of a tree. In the event of relocation, the Advisory Agency may designate measures to be taken to mitigate adverse effects on the tree. (b) Permit protected trees of a lesser size, or trees of a different species, to be planted as replacement trees for protected trees permitted by this Code to be removed or relocated, if replacement trees required pursuant to this Code are not available. In that event, the Advisory Agency may require a greater number of replacement trees. 3. Historical Monuments. The Advisory Agency, except as to Subdivision 1.(b)(iii) above, shall require retention of a protected tree at its existing location, if the tree is officially designated as an Historical Monument or as part of an Historic Preservation Overlay Zone. 4. Requirements.