Kevin W. Farge
Natural Areas Journal 38 (2), 168-182, (1 April 2018) https://doi.org/10.3375/043.038.0207
KEYWORDS: bottomland forest, heavy-seeded, passive restoration, reforestation, second-growth
Located southwest of Houston, Texas, the Columbia Bottomlands comprise a significant complex of the bottomland hardwood forest ecosystem. As the largest expanse of forest adjacent to the Gulf of Mexico in Texas, the Columbia Bottomlands are critical stopover and staging habitat for Nearctic—Neotropical migratory landbirds. They have been cleared to less than one-quarter of their historical extent of 283,000 ha. Restoration of bottomland forests has predominantly focused on planting just a few heavy-seeded, mast-producing species, such as oaks (Quercus spp.) and hickories (Carya spp.), but such active restorations often fail to meet management objectives of vertical structural complexity, unevenly aged trees, standing dead snags, and coarse woody debris, and do not adequately develop into quality habitat for birds and other wildlife. This study investigates the potential for passive restoration—colonization via natural dispersal—to restore previously cleared areas of bottomland floodplains. Vegetation surveys were conducted in passively restored second-growth forest of varying ages within the Columbia Bottomlands to quantify the structure and composition of vegetation regrowth, and compared to a nearby old-growth stand. At 18–20 y old, the Dance Bayou Site resembled a young forest with open areas of dense vines. At approximately 50–72 y old, the Sweeny Site had characteristics of a mature forest, with vertical structural complexity, unevenly aged trees, standing snags, coarse woody debris, and a greater richness of woody plant species than a nearby old-growth stand. The passively restored sites adequately recruited heavy-seeded species. Passive reforestation has great potential in the Columbia Bottomlands.