Section 69G. Every city or town may establish an office of lands and natural resources. Said office shall have charge of such lands as may be committed to its care and may perform such maintenance and improvement work on other municipal lands as may be permitted by the board, department, commission or committee in charge thereof. Said office shall exercise the duties of tree warden and superintendent of insect pest control, and upon the establishment of said office and offices of tree warden and superintendent of insect pest control shall be abolished. Said office shall be under the control of a director qualified by training and experience in the field of arboriculture and licensed by the pesticide board in the department of environmental protection. The city manager or the town manager in a city or town having such manager, the mayor in any other city and the selectmen in any other town shall appoint said director for a term of three years. The commissioner of environmental management shall be notified in writing forthwith by the city or town clerk of said appointment and the name and address of said director. The director may appoint such assistants as appropriations permit. He shall have control of all sums appropriated for and to be expended by the office and may apply for and receive such federal, state and county assistance as may be available. Nothing contained in this section shall be construed to affect the powers and duties of a conservation commission established under section eight C of chapter forty.