The distribution of biomass and energy content was determined for even-aged, fully stocked , 10-, 20-, 40- and 60-year-old Atlantic and Gulf Coastal Plain river bottom (red and black), wet flat, and swamp (muck and peat) forest ecosystems. Small differences in interspecies caloric values (kilogram calories per kilogram dry weight) were observed. These ranged from 4503–5018 kcal/kg for foliage, 4456–4792 for branches, 4456–4868 for stem wood, and 4242–4951 for stem bark. Mean caloric values decreased in the order of foliage > stem wood > branch > stem bark. Maximum caloric value differences among the three bottomland hardwood forest types for Acerrubrum were 2.5 (foliage), 2.3. (branch), 1.8 (stem bark), and 0.9 (stem wood), and for Liquidambar styraflua were 4.3 (branch), 3.1 (foliage), 2.3 (stem bark), and 0.8 (stem wood) percent, respectively. Sapling trees (⩾ 2.5 < 12.7 cm dbh), foliage, subordinate vegetation (ground plus understory), and forest floor [litter (L), fermentation (F), and humus (H)] energy content (caloric value × dry weight biomass) decreased relative to the total aboveground forest ecosystem energy content throughout secondary forest succession. Energy content of trees ⩾ 2.5 cm dbh (foliage, branch stem wood and stem bark) comprised 79 (river bottom), 73 (wet flat), and 58 (swamp) percent of the total aboveground energy content of 10-year-old stands and increased to a maximum of 99 (swamp), 98 (river bottom), and 96 (wet flat) percent of the total aboveground energy budget of 60-year-old bottomland hardwood forests. Total aboveground (plus forest floor) energy content of 10-, 20-, 40- and 60-year-old swamps, wet flats, and river bottoms was 325.0, 605.6, 1082.8 and 1432.1; 269.3 447.7, 838.5 and 1137.3; and 250.1, 697,4, 1051.0 and 1086.2 × 10 6 kcal/ha, respectively. Conventional harvesting regimes (all stems ⩾ 12.7 cm dbh to a 10-cm dob top) were estimated to remove approximately 72 (swamp), 69 (wet flat), and 64 (river bottom) percent of the energy accumulated in 60-year-old forests. Whole-tree harvest (all material of trees ⩾ 2.5 cm dbh) removed an additional 396.2, 402.8 and 382.9 × 10 6 kcal/ha in 60-year-old swamp, wet flat and river bottom forests, respectively.