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Title: Spatial variation in seed bank dynamics of two annual brome species in the northern Great Plains

Author
item Espeland, Erin
item MANGOLD, JANE - Montana State University
item West, Natalie

Submitted to: Prairie Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2016
Publication Date: 11/12/2016
Citation: Espeland, E.K., Mangold, J., West, N.M. 2016. Spatial variation in seed bank dynamics of two annual brome species in the northern Great Plains. Prairie Naturalist. 48(2):96-101.

Interpretive Summary: Annual bromes decrease forage production in northern central plains rangelands of North America. Seedlings are particularly vulnerable yet studying death post-germination and prior to emergence is difficult. I collected seeds from litter and soil over the course of two growing seasons and catalogued the number of seeds where the root had emerged and the seedling had died (failed germination). I show that as much as 79% of annual brome seeds can be lost to failed germination. The two annual brome species reported on here, downy brome and field brome, have different patterns of failure. Field brome did not exhibit variation in failure over small spatial scales, but did show differences between study sites. Downy brome failure was highly variable over small spatial scales as well as among collection events. Pre-emergent weed control may be effective for one species but not the other unless species differences are taken into account.

Technical Abstract: Annual bromes decrease forage production in northern central plains rangelands of North America. Early life history stages are when plants are most failure-prone, yet studying death post-germination and prior to emergence is difficult. In seed bank collections conducted over the course of two growing seasons, I observed seeds from which short roots had emerged, but the coleoptile had not. When these seeds represent failed germination events, I show that as much as 79% of annual brome seeds in the seed bank can be lost to failed germination. The two annual brome species reported on here, downy brome and field brome, have different patterns of failure. Field brome did not exhibit variation in failure over small spatial scales, but did show differences between study sites. Downy brome failure was highly variable over small spatial scales as well as among collection events. The efficacy of weed control technologies that rely on increasing mortality at the pre-emergent stage will likely be driven by different factors for downy brome compared to field brome.