Section 81C. The planning board established under section eighty-one A shall from time to time make careful studies and when necessary prepare plans of the resources, possibilities and needs of the city or town, and, upon the completion of any such study, shall submit to the city council or selectmen a report thereon, with its recommendations. A copy of each completed study shall be furnished to the department of housing and community development. Said planning board shall report annually to the city council or to the annual town meeting, giving information regarding the condition of the city or town and any plans or proposals for its development and estimates of the cost thereof, and shall at the same time furnish a copy of its report to the department of housing and community development. The planning board of a town established under section eighty-one A may be authorized by vote of a town meeting to act as park commissioners therein, and may be vested with all the powers and duties of park commissioners in towns.