Author
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Tracy, Benjamin |
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Sanderson, Matt |
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Submitted to: Ecological Applications
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/13/1999 Publication Date: N/A Citation: N/A Interpretive Summary: The most economical way to maintain additions of desirable plant species in pasture is to rely on germination from existing seed in soil. This reservoir of seed in soil is typically called the soil seed bank. In this study, we evaluated the species composition of soil seed banks in 36 pastures across the northeast United States. Objectives of this study were eto quantify the seed bank species composition of pastures managed for intensive grazing and hay production and determine the abundance of useful forage species (e.g. grasses and legumes) in the seed bank. Soil seed banks from these pastures were dominated by seedy, fast growing plants like lamb's quarters and dandelion, which contributed little useful forage for cattle. Except for bluegrass, useful forage grasses were largely absent from the seed bank. White clover was the most abundant legume in these pasture seed banks. We conclude that soil seed banks from northeastern pastures contain significant amounts of bluegrass and white clover that ar important for sustaining productive pasture land. These seed banks, however, will not supply a diverse assemblage of useful forage species. If farmers seek to establish diverse, mixed-species pasture, then re-seeding pastures with desired mixtures may be the only option. Technical Abstract: Knowledge about the species composition of buried seed, or seed bank, in plant communities is essential to achieve a more complete understanding of local vegetation dynamics. Although much is known about soil seed banks from mid-western and western grasslands of the United States, little information exists on soil seed bank resources from northeastern grasslands. In this study, we evaluated the species composition of soil seed banks in 36 pastures across the northeast United States. The objective of this study was to quantify the soil seed bank composition of pastures managed for intensive grazing and hay production. The focus of the survey was to determine the relative abundance useful forage species (e.g. perennial grasses and legumes) present in the seed bank and relate the composition of the seed bank to existing vegetation on these pastures. Germinable seed was dominated by annual and perennial forbs, most of which contributed little useful forage for cattle. Perennial grasses, except fo Poa pratensis (bluegrass), were largely absent from the germinable seed bank, while legumes were more abundant. Seed bank species composition showed little similarity to the existing vegetation. An exception to this trend were Poa, Trifolium repens (white clover), and Taraxacum officinale (dandelion). These species were abundant in both the germinable seed bank and in the existing vegetation on most pastures. Our data suggests that these three species may perpetuate their dominance in grazed pastures through recruitment of seed bank individuals. Grazing may have affected the germinable seed bank, particularly by increasing the abundance of Trifolium repens and decreasing the abundance of some annual forbs. Overall, our study suggests that seed banks in these northeast pastures |
