As southern Maine prepares for passenger rail service to return this year, state and local officials fear the region’s first large-scale public transportation service will swell the ranks of people who choose to live in Maine and commute to work elsewhere.

Their fear is sprawl: New residents will mean too many new homes and new businesses, chewing up rare open spaces and putting more pressure on public resources.

This worry could be a sore point for people in northern, eastern and central Maine, where open space is hardly an issue, but economic development and affordable transportation are. But such disparities hardly vacate the statewide implications of too much development taking place south of Augusta. Overpopulation, pollution and sprawl there spell public-policy problems, and expense, that everyone in Maine must deal with.

Already, it’s difficult to find many places in the southern part of the state that haven’t been cut by a road or subdivided into house lots. With the convenience of rail transportation from Portland south making Boston a 90-minute commute, the urge to flee the city and own a small part of Maine’s fabled quality of life could easily prove too much for many to resist.

When we think of preserving Maine’s lands for the future, we often think of north woods timberlands, places such as Mount Kineo and the West Branch of the Penobscot River. But nowhere is open space more threatened than southern Maine. The working forest has helped protect over 11 million acres of Maine timberlands, mostly located in the north and west of the state. Certainly, changes can be made to better protect such timberlands and shore up land-use permissions; but in terms of access, private ownership of those lands has ensured public use. Open access remains alive in the northern part of Maine, but it is threatened in the south. The $50 million land bond approved by voters last November provides the means to protect open spaces of high public value.

But beyond the public purchase of a few choice parcels, the state and the effected communities must take action on a subject that until now has received mostly talk. The State Planning Office has made some valuable recommendations on how sprawl can be stopped, or at least made to pay for itself. Several of those recommendations are included in legislation being considered this session.

The cost of sprawl is high, in both dollars and quality of life. As population moves from town centers to the countryside, there is unneeded school and road construction, plus the expensive extension of utilities and other services, plus traffic. Maine has been caught napping by sprawl before — the extensive, clogging development along the Coastal Connector in Brunswick and the new Turnpike exit at the Portland Jetport being two recent examples. This time, the sprawl can be seen coming from way down the track.