With its stately brownstones and trendy cafes, the Park Slope neighborhood in Brooklyn might seem an unlikely place to produce a Southern country-rock trio. But the members of the Lone Bellow are all transplants there from small Southern towns, and though they have made a life in Brooklyn, their stomping, acoustic sound seems rooted in the places they grew up, drawing on that region’s country, soul, gospel and folk. “I call it country-soul,” said Kanene Pipkin, one of the members.