(a) Existing landscaping or natural vegetation, as shown on a landscaping plan and that are in satisfactory condition, may be used to meet the standards and satisfy the requirements of this chapter in whole or in part, if protected and maintained during the construction phase of the development.
(b) Every development to which this chapter applies shall retain all existing trees eighteen (18) inches in diameter or more, unless during the site plan or development plan review process, it is determined by the Planning Commission that the retention of such trees would unreasonably burden the development.