Complex drivers of sugar maple (Acer saccharum) regeneration reveal challenges to long-term sustainability of managed northern hardwood forests

•We surveyed northern hardwood forests managed with selection silviculture.•Large geographic extents have low sugar maple regeneration densities.•Sugar maple sapling classes are particularly understocked.•Predictive factors include deer use, seed limitation, and understory competition.•Alternative forest management may be necessary to sustainably manage sugar maple.