Improvements to the parking lot next to the Roseburg National Cemetery began Tuesday afternoon when contractor Dave Bass used an excavator to pull down two maple trees near the cemetery entrance. It was the first step in renovating the mostly unpaved, pothole-ridden parking lot, which veterans groups have complained about for at least a dozen years. They say the city-owned lot is unsafe for elderly and disabled people and not worthy of the veterans whose relatives have come to mourn them. As he watched the first branch come down just after 4 p.m., Roseburg City Councilor Bob Cotterell said he’s …