PARENT SESSION
Thursday, August 10, 8:00-11:30 am
COS 84 - Community ecology III: species composition
L-5, L-6, L-7, Lobby Level, Cook Convention Center
Presiders: C Paine
Influence of forest history and physical environment on the herb composition of second-growth forest, Strouds Run, Ohio, US.
Harrelson, Sarah1, Matlack, Glenn*,1, 1 Ohio University, Athens, OH
ABSTRACT- Historical land use in eastern North America and much of Europe has created a mosaic of successional forest stands of widely varying age. At second-growth forest sites in southeastern Ohio, we estimate the rate of successional herb community development and the extent to which physical gradients determine herb distributions. Thirty-five plots were surveyed in old (82-193 years) and young (35-40 years since pasture) deciduous forest stands. In each plot, herb species cover and environmental factors were measured. Herb community composition was clearly distinguishable between oak-dominated upland sites and mixed mesophytic stands in moist ravines. In both community types, young stands were compositionally distinct from old stands. Species lacking obvious seed dispersal mechanisms were disproportionately uncommon in young stands, implying dispersal limitation in the process of recolonization. Among old stands distributions of many species showed significant regressions on the environmental variables, whereas few showed significance in young stands. Species with weak dispersal tended to be more frequently linked to environmental gradients in old stands than in young stands. Early arriving forest species appear to assort rapidly along physical gradients, defining communities early in the successional trajectory. The re-assembly of the full forest community continues over a longer period as individual species assort on environmental gradients at rates determined by their dispersal abilities. Thus, long-established stands show more spatial variation than successional stands, and offer greater opportunities for conservation of the forest community.
Key words: forest history, forest herb, forest succession