For the purposes of this article, the following words shall have the meanings hereafter ascribed to them unless the context clearly indicates otherwise:
(a) “Timberland” means any surface real property except farm woodlots of not less than ten contiguous acres which is primarily in forest and which, in consideration of their size, has sufficient numbers of commercially valuable species of trees to constitute at least forty percent normal stocking of forest trees which are well distributed over the growing site.
(b) “Managed timberland” means surface real property, except farm woodlots, of not less than ten contiguous acres which is devoted primarily to forest use and which, in consideration of their size, has sufficient numbers of commercially valuable species of trees to constitute at least forty percent normal stocking of forest trees which are well distributed over the growing site and that is managed pursuant to a plan provided for in section ten of this article: Provided, That none of the following may be considered as managed timberland within the meaning of this article:
(1) Any tract or parcel of real estate, regardless of its size, which is part of any subdivision that is approved or exempted from approval pursuant to the provisions of a planning ordinance adopted under the provisions of article twenty-four, chapter eight of this code; or