PARENT SESSION
Oral Session #62: Vegetation change: Succession, recovery, facilitation. Presiding: S. Franklin.
Thursday, August 9, 2001. 8:00 AM to 12:00 PM. Hall of Ideas G.
Secondary forest succession in southeastern floodplain forests.
Allen, Bruce1, Sharitz, Rebecca1, 1
ABSTRACT- Patterns of secondary succession were examined in seven southeastern floodplain forests over a 22 year period. These stands are located along a hydrologic gradient on small and large river floodplains in the Savannah River drainage on the upper Coastal Plain of South Carolina. They were periodically logged between 1879 and 1950. In 1979, a 1-ha plot was established in each stand and woody stems ≥ 4.5 cm were measured and mapped; plots were re-sampled in 1989, 1995, and 2001. Patterns of mortality and survival, and of recruitment and growth of canopy species, may indicate paths of succession in floodplain forests. In all stands, mean tree diameter is increasing while overall density is decreasing. Emerging patterns include a shift in canopy composition with a decline in shade-intolerant species and development of a subcanopy. Specifically, ingrowth to mortality ratios ≥ 1.0 indicate that shade-tolerant subcanopy species (Ilex opaca, Ilex decidua, Cornus florida) and a woody vine (Vitis rotundifolia) are increasing in density. Only a few potential canopy species have had higher ingrowth than mortality, including Fagus grandifolia and Quercus laurifolia; whereas Liquidambar styraciflua, Q. nigra, and Q. michauxii are declining. These forests are increasing in structural complexity and species diversity as stem density declines.
KEY WORDS: southeastern floodplain forest, secondary forest succession, shade-tolerance , tree population dynamics