If it appears to the local planning authority that—
are not complied with in the case of any tree or trees, that authority may serve on the owner of the land a notice requiring him, within such period as may be specified in the notice, to plant a tree or trees of such size and species as may be so specified.
A notice under subsection (1) may only be served within four years from the date of the alleged failure to comply with those provisions or conditions.
A notice under subsection (1) shall specify a period at the end of which it is to take effect.
The specified period shall be a period of not less than twenty-eight days beginning with the date of service of the notice.
The duty imposed by section 206(1) may only be enforced as provided by this section and not otherwise.