Comparison of Standing Vegetation and Seed Bank Composition One Year Following Hardwood Reforestation in Southwestern Ohio

Abstract

Successful conversion of pastures to forest is often hindered by the lack of structural complexity, which in turn reduces seed dispersal and recruitment of trees and shrubs. A long-term restoration study was initiated on a former pasture at the Fernald Environmental Management Project in southwestern Ohio. Our objective was to establish a planting design that has the potential to accelerate the restoration and succession of a site by creating structural complexity with uneven-aged stands of native trees. Changes in herbaceous vegetation composition were observed among the planting treatment by the end of the first growing season. We hypothesized that the vegetation differences could be attributed to recruitment from the seed bank following planting related disturbances. The standing vegetation and seed bank were evaluated to determine if differences in above-ground vegetation observed among plots could be explained by differences in composition of the seed bank. Using principle coordinates analysis (PCO), we found that herbaceous composition differed significantly (P <0.0001) from other planting treatments where high densities of saplings were planted, specifically due to a significant increase in perennial herbs (P <0.001). Based on cluster analysis, the seed bank and above-ground vegetation composition form two discrete groups, suggesting the seed bank does not fully account for standing vegetation. We attribute this compositional change to increased colonization via wind-dispersal and rhizome exposure of gaps created in the pasture grasses following planting disturbance. The results of this study suggest that disturbances related to restoration planting may dramatically alter the herbaceous vegetation composition of a site.