Patterns of seedling emergence from North Dakota grazing lands invaded by Kentucky bluegrass

Authors: Halvorson, Jonathan; Hendrickson, John; Toledo, David

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/2022
Publication Date: 8/17/2022
Citation: Halvorson, J.J., Hendrickson, J.R., Toledo, D.N. 2022. Patterns of seedling emergence from North Dakota grazing lands invaded by Kentucky bluegrass. Rangeland Ecology and Management. 84:126-133. https://doi.org/10.1016/j.rama.2022.07.003.
DOI: https://doi.org/10.1016/j.rama.2022.07.003

Interpretive Summary: Kentucky bluegrass is an important invasive grass in the northern Great Plains but little is known about its impact on plant seeds in and near the surface of the soil. We measured seedling appearance and determined the number of individuals and species in different layers, grass litter, thatch, and mineral soil, collected from grazing lands near Mandan, ND. Many more seedlings and, in particular, more Kentucky bluegrass emerged from litter material, than the other layers. Plots of the number of seedling species for the layers demonstrated a common pattern; a single main species, several more species with low abundance and most species represented by very few individuals. Kentucky bluegrass was the most prevalent species accounting for 94.3%, 71.9%, and 69.9% of seedlings that emerged from litter, thatch and soil layers, respectively. These plots also indicated that while there were fewer species represented in soil compared to litter, their numbers were more evenly distributed. These results are useful to grassland managers and researchers for identifying how seeds are distributed in and near the soil surface and contribute to development of effective Kentucky bluegrass management strategies.

Technical Abstract: Kentucky bluegrass (Poa pratensis, POPR) is a dominant invader of the northern Great Plains but little is known about its impact on seedbanks. We quantified patterns of seedling emergence from samples of litter, thatch and mineral soil collected from invaded grassland sites hypothesizing that POPR would be the dominant emergent species, but that composition of seedling populations would differ between the layers with a higher incidence of native species in mineral soil. POPR accounted for 84% of the emergent seedlings and curves, fit with a Hill model, indicated that 50% of cumulative emergence was reached after 40.5 days. Rank abundance diagrams were highly skewed and strongly dominated by POPR but indicated differences between litter, thatch, and soil layers. POPR accounted for 94.3%, 71.9%, and 69.9% of emergent seedlings from litter, thatch, and soil layers, respectively. More POPR seedlings emerged from litter material, than the other layers. Management of POPR by fire or grazing should consider their possible effects on seed production and distribution and longevity of buried seeds.