Seed Bank Effects on Recovery after Disturbance in Reconstructed Tallgrass Prairies

Litter-removing disturbances such as fire in grasslands temporarily increase available resources for plants, opening a window of opportunity for new establishment as communities recover. At this time, new individuals or species could be added to the community as a result of germination from the local seed bank. In reconstructed grasslands this may be problematic, as the seed bank may contain a suite of undesired species reflective of prior and surrounding land uses. In two, 25-year-old, low-diversity reconstructed grasslands, we tested the effect of local seed bank establishment following litter-removing disturbance using seedling removal plots (1 m2) and plots where natural seedling establishment was allowed. Following disturbance, the vegetation was either left intact or hayed to enhance seedling establishment (a common practice following inter-seeding efforts). Although the seed bank and seedling community were dominated by resident grasses (Andropogon gerardii and Poa pratensis), recruitment from the seed bank increased species richness and reduced evenness through the addition of forb species (including Cirsium arvense) in one of the study sites. Haying temporarily altered the abundances of the dominant grasses, but did not consistently affect seedling recruitment. Disturbances that facilitate seed bank recruitment may promote establishment of undesired species within reconstructed grassland communities, and we need to take steps to better manage the contributions into and recruitment from the seed bank to reconstruct sustainable grasslands.