Submitted to: Forest Service Meeting
Publication Type: Proceedings
Publication Acceptance Date: January 5, 2004
Publication Date: February 1, 2004
Citation: Haferkamp, M.R., Macneil, M.D. 2004. Annual brome seed germination in the northern great plains: an update. Forest Service Proceedings RMRS-P-31. p. 115-119. Interpretive Summary: Annual bromes are clearly adapted to the Northern Great Plains. The high level of germination exhibited by after-ripened seeds suggests a large portion of the disseminated seeds will germinate wtih available water during late summer and early autumn. The secondary dormancy state attained by some seeds will also enhance the species persistence on rangelands, because seedlings emerging in August and September in any year likely come from two seed crops, the current and previous years. Fluctuations in environmental conditions will continue to cause erratic fluctuations in animal brome populations on Northern Great Plains rangelands. However, due to the large seed banks and ability of seeds to germinate in variable environmental conditions, we think animals bromes will persist on these rangelands for many years in the future.
Technical Abstract: Japanese brome (Bromus japonicus Thunb) and downy brome (B. tectorum L.), alien weedy cool-season annual grasses, have invaded thousands of hectares of grass and shrub communities in the Northern Great Plains, Great Basin, and Columbia Basin. Abundance of brome is dependent upon availability of seed, amount and distribution of rainfall, temperature, and availability of soil nitrogen. More than 10,000 annual brome seeds can be present in a square meter in the mixed-grass prairie of the Northern Great Plains. A large portion of ripe seeds can be present in a square meter in the mixed-grass prairie of the Northern Great Plains. A large portion of ripe seeds will generally geminate over a wide range of temperatures and osmotic potentials that often occur in late summer and autumn, but soils usually must be moist for 3 to 5 days for seeds to germinate. However, a percentage of seeds that do not germiante by late September can become dormant when water is taken up at or below 0 degree C. This dormant state can last through the next winter, spring, and summer. These characteristics aid annual brome's persistence on rangelands.