Forested land of 5 acres or more in Maryland and 10 acres or more in Pennsylvania can be taxed at a lower rate than both residential and agricultural land. In both states, the landowner must apply for the tax break.
Maryland has a more rigorous program to ensure that the tax break encourages actual forest improvement over time. To qualify in Maryland, you must have a forest management plan, and have the property re-inspected every three years by a licensed forester to verify progress according to the plan. Reynwood Forest Management is able to provide this service.
{Forester's rant: Pennsylvania's Clean & Green program has little to do with professional forest management. The state has really dropped the ball with that program and will suffer for it in multiple ways in the future. Why bother to have a "forest reserve" if that forest is ignored or allowed to be degraded by poor harvesting practices? Why ask if there is a "management plan" if there is no criteria or accountability? Project that scenario over the next 100 years and the forest will be degraded, landowners will lose potential income, the state will lose value-added taxes, the forest industry will be harmed, and society will not realize the ecosystem benefits it could have accrued. To make matters worse, anyone can call themselves a "forester" in PA - no training or licensing needed. Let the landowner beware. End of rant.}