MARBLEHEAD – The Marblehead Conservancy will continue to clear and improve walking trails this year in 20 acres of town-owned forest between Seaside Park and the shoreline, at no cost to the town.The Recreation and Parks Commission, which controls Seaside Park and the open space adjacent to it, gave permission for the work to continue after discussing a detailed report from Conservancy spokesman Don Morgan.Conservancy volunteers are scheduled to fill low spots, grade two areas for easier walking, prune some plants, stabilize the edge of a trail that has been damaged by erosion, and erect a sign and map dispenser at the trail entrance. That will be Phase III of a plan that started in October 2010.In November the Conservancy got a helping hand from the Boy Scouts as Chris Pedersen and 30 Eagle Project volunteers worked an average of 5? hours each to clean and upgrade 415 feet of trail. That was Phase II.When Morgan finished his report, Recreation and Parks Commission Chairman Chip Osborne told him, “This is very impressive. That?s a lot of work done.”Phase IV, which has yet to be scheduled, will include further work on less-used areas of the property and decisions on wetland area care and the care of a small pond on the site.