WASHINGTON, April 16 (Reuters) - U.S. homebuilding rebounded more than expected in March, but soaring lumber prices amid supply constraints could limit builders’ capacity to boost production and ease a shortage of homes that is threatening to slow housing market momentum. Housing starts surged 19.4% to a seasonally adjusted annual rate of 1.739 million units last month, the Commerce Department said on Friday. Economists polled by Reuters had forecast starts would rise to a rate of 1.613 million units in March. (Reporting by Lucia Mutikani; Editing by Toby Chopra)