In any county having a population of more than one hundred and fifty thousand, the board of chosen freeholders may elect five persons, to be known as the county park commissioners, who shall hold their office for two years from the date of their appointment, and shall serve without compensation. Vacancies may be filled by the board of chosen freeholders for the unexpired terms only.

The commissioners shall consider the advisability of laying out ample open spaces for the use of the public in such county, and may make maps and plans of such spaces and collect such other information in relation thereto as the board may deem expedient.

As soon as is conveniently possible within their term the commissioners shall make a report in writing of a comprehensive plan for laying out, acquiring and maintaining such open spaces.