Maryland officials have mapped a 2-million acre plan to save the best remaining examples of “ecologically significant” lands before they are consumed by sprawl.

Dubbed “GreenPrint,” the ambitious program identifies a series of “green hubs” — large intact forests, wetlands and other unique ecosystems — and connects them through a series of wide corridors, called “green links.”

This “green infrastructure,” as the state refers to it, is critical for the long-term survival of native plants and wildlife, maintenance of resource-based industries such as forestry, and the protection of the supply of clean water.

Just as the state pours millions of dollars into maintaining its “gray infrastructure” of roads and sewage pipes, this year, Gov. Parris Glendening is seeking General Assembly support for a five-year, $145 million program to help maintain part of that green infrastructure.

“Once a field has been paved over, or a forest plowed under, we cannot go back and undo that damage,” Glendening said. “We must act now while we have the money.”

If approved, the program would also move the state toward meeting the Bay Program commitment of permanently protecting 20 percent of the Chesapeake’s watershed as open space by 2010.

The program has not drawn much outright opposition, but some lawmakers have questioned whether the state can afford the extra spending.

The program has won praise from many environmentalists. “It’s an excellent program, and one of the best in the country in terms of interconnections within a state,” said Bob DeGroot, president the Maryland Alliance for Greenway Improvement and Conservation.

The state spends millions of dollars every year on various land programs, but those often have other purposes, such as protecting farmland, and the money is scattered among jurisdictions throughout the state.

The GreenPrint funding, by contrast, would go exclusively to protect targeted areas. “We are aiming this at the most valuable remaining ecological lands in Maryland,” said David Burke, director of Chesapeake and Coastal Watershed Services with the Maryland Department of Natural Resources. “The purposes of protecting those other open areas are quite different from this.”

Still, the $145 million — if the program is fully funded — would cover only a fraction of the GreenPrint map.

Of the 2 million acres, only about 26 percent is now protected, leaving nearly 1.5 million acres vulnerable. “We acknowledge that it’s not feasible to conserve that much land, nor did we intend to,” Burke said.

The $40 million proposed for next year would protect about 13,000 acres.

The amount of land that is ultimately preserved will depend in large part on whether land trusts, civic groups, local governments and others join the effort and use the GreenPrint map to target their programs.

“Hopefully, this begins an important process that involves lots of folks reading from the same music sheet, so to speak,” Burke said.

The GreenPrint Program has no regulatory authority. Burke said the state would only work with willing sellers on land acquisitions. And, while Burke said he hopes local governments incorporate GreenPrint maps into their local planning initiatives, they are not required to do so.

In some cases, Burke said, the map already shows green infrastructure lands where local zoning does not call for conservation-oriented uses. That could place some new developments on top of some unprotected GreenPrint lands in the future.

As a result, some of the GreenPrint lands will be lost over time. Burke said the maps, years in the making, were developed so people would at least have information about ecologically important areas when making decisions. Whether they use the information, he said, is up to them.

Burke described the maps as “science-driven.” GreenPrint lands were identified by using layers of computerized, mapped information that identifies important ecological communities, rare species, large tracts of forests, wetland complexes and other important natural areas.

Hubs include such areas as the marshes of Blackwater Wildlife Refuge on the Eastern Shore and Savage River State Forest in Western Maryland. Most hubs are more than 2,000 acres in size.

In the case of forests, they are large enough to provide interior habitat for species, such as certain songbirds, that are vulnerable to predation by animals that live on the forest edge.

Those hubs are linked by 1,100-foot wide corridors, a width suggested by scientific literature as sufficient to protect the core area of the forested link from exotic species encroachment and to allow movement by animals from one place to another. Such connections are important because, studies suggest, as habitat areas shrink and populations are cut off from one another, they are more likely to disappear.

But the green infrastructure protects more than just wildlife, Burke said. It also protects drinking water supplies, preserves marshes that are important for the seafood industry, and keeps large forests intact, which is important for resource-based industries such as forestry.

“We are trying to get away from a single purpose, or single reason for conserving the land,” Burke said.

While the maps reflect what exists today, Burke said it’s inevitable that parts of the GreenPrint lands — which cover nearly a third of the state — will be lost. Maintaining certain corridors, he said, is already problematic. “We are going to lose thousands of these acres of green infrastructure if history is any witness to the future,” he said.

Some of the corridors already have small gaps in them, but perhaps not so large as to prevent animal movement, Burke said. Also, some corridors are not the full 1,100-feet that is recommended. It’s possible, he said, that some of those gaps could be targeted for restoration in the future.

Likewise, he said, the GreenPrint program could help guide where wetland restoration programs, and stream buffer programs prioritize work. “Those are the great possibilities,” Burke said.