Data were collected in 28 riverine and 28 palustrine swamps were selected (N sites = 56), evenly divided among the two watersheds (Bécancour and Yamaska rivers) and the two ecoregions (St. Lawrence Lowlands and Appalachian foothills). A riverine swamp was defined as one directly crossed by a permanent river or located within 20 m of a riverbank. A palustrine swamp was defined as being at least 300 m from a mapped permanent river. In order to sample each swamp equitably, one plot was allotted per hectare in size (i.e., 5 ha = 5 plots), with a minimum number of 3 plots per swamp. Overall, a total of 112 and 101 plots were surveyed in riverine and palustrine swamps, respectively (N plots = 213).