COS 85-1 - Composition and distribution of forest herb communities differs with land-use history

Thursday, August 11, 2016: 1:30 PM
Palm A, Ft Lauderdale Convention Center
Marion A. Holmes and Glenn R. Matlack, Environmental and Plant Biology, Ohio University, Athens, OH

Herb communities in post-agricultural deciduous forests are compositionally and structurally distinct from minimally-disturbed forests, possibly as a result of environmental filtering or demographic process. The general effects of land use are well-documented, but the impacts of specific agricultural practices are less understood. We examine recolonization by forest herbs and the dynamics of herb communities on post-agricultural land.  We tested the hypothesis that community composition would initially differ stands with contrasting land use, and that community types would converge through successional time as physical contrasts diminished.  As an alternative hypothesis, community composition potentially diverges as populations are filtered by contrasting environments.


Forest stands were selected on abandoned pastures and cultivated fields to form a replicated chronosequence spanning 0-80 years.  Five minimally-disturbed mature stands >120 years were included as a control. Stand age and land-use history were determined using historical photographs,  surface microtopography, and soil profiles. Herbaceous vegetation, environmental variables and soil characteristics were recorded.  Forest herb community composition changed through successional time and differed between pastured and cultivated sites. Early colonizing weed species generally did not persist more than 40 years past canopy closure. Shade-tolerant native species dominate after 40 years, but composition is still distinguishable from the control at 80 years. Community composition within age classes was influenced by environmental variables at each site, demonstrating an interaction between site characteristics, forest age, and land-use history.  Thus, the legacy effects of agriculture persist for at least 80 years suggesting environmental filtering.  Full re-assembly of the forest herb community occurs on longer time scales than measured in this project.