Gov. Corbett on Friday signed an executive order lifting a 2010 moratorium on leasing additional state forests for Marcellus Shale natural-gas development, but it prohibits new leasing that would cause additional surface disturbances.

The order puts into effect a promise the governor made in February to generate $75 million for state coffers by leasing Department of Conservation and Natural Resources lands adjacent to public and private land already under existing leases that can be developed using horizontal drilling.

"With this executive order, I am directing that the commonwealth maintain a moratorium on any additional gas leasing of DCNR lands that involves long-term surface disturbance, such as placing well pads, roads, or pipelines in the newly leased areas," Corbett said.

"This balanced approach will ensure that the special characteristics and habitats of DCNR lands are conserved and protected, and will also provide for historic investments in conservation programs, our schools and quality health care, without raising taxes on Pennsylvanians."

Corbett's announcement in February that he would lease new state lands drew flak from conservationists and anti-drilling activists, who said that any drilling, even that which did not require new surface disturbances, would disturb the environment.

"This decision is clearly so toxic to the public that the governor is releasing it late on a Friday afternoon before a three-day holiday," said John Hanger, the state environment secretary under Gov. Ed Rendell, who signed the 2010 leasing ban that was rescinded Friday by Corbett's action.

Though new lease payments would be channeled to the state's general fund, Corbett's order also provides that all future royalties derived from oil and gas production would support state forests and parks.

Royalties, which are a share of the sales of oil and gas production, would be used to make improvements to state forests and parks, to acquire new lands, or to buy mineral rights underlying "high-value" surface lands.

Last year, the state generated about $110 million in oil and gas royalties that mostly went to running DCNR operations.

The use of royalty income to buy mineral rights would address a potential hot-button issue: drilling in state parks.

Many state lands are what are known as "split estates" - the mineral rights are separately owned by private parties. By law, the owners of the subsurface rights can access the land's surface, meaning a drilling company could set up a rig in a state park to explore for oil and gas. By acquiring mineral rights under sensitive lands, the state would gain full control over the surface.

No drilling has taken place in parks thus far, but some split-estate land, such as Ohiopyle State Park in Fayette County, are considered vulnerable because drilling is taking place nearby.

Corbett's critics said the timing of the announcement seemed suspicious.

Commonwealth Court has scheduled a hearing for Wednesday on a suit by the Pennsylvania Environmental Defense Foundation that challenges Corbett's plan to use royalty income for DCNR's operating budget. The group is seeking an injunction to stop new leasing.

John Quigley, former DCNR secretary under Rendell, also said that only the state legislature has the power to approve how royalty income is spent. "Corbett does not have the authority to direct the utilization of royalty income," he said.

Critics including State Rep. Greg Vitali (D., Delaware) have also expressed skepticism that the state can generate $75 million from new leases, and have pressed the governor to identify which parks and forests are under consideration.