Twenty-Fourth Annual Meeting and Symposium of the Desert Tortoise Council, March 5-8, 1999
Abstracts

Our experience is almost entirely with the ecology and control of Bromus tectorum; therefore, we will confine our comments to that species. B. tectorum is the dominant annual invasive grass in the temperate desert portion of the Great Basin, where the occurrences of B. madritensis subsp. rubens are very limited. B. tectorum is widely distributed in Artemesia/bunchgrass, Pinus/Juniperus, and Atriplex potential sites. The two key words in B. tectorum ecology are “water” and “fire”. B. tectorum seedlings out compete the seedlings of most native herbaceous and woody species for soil moisture. B. tectorum closes the site to the establishment of seedings of perennials, effectively truncating succession. The accumulations of fine textured, densely occurring herbage of B. tectorum increase the chance of ignition and rate of spread of wildfires. The large seedbank of B. tectorum insures the regeneration of the annual grass the season after burning. B. tectorum populations are highly variable and remarkably dynamic. During dry years, populations may entirely disappear to be subsequently renewed from seedbanks. A single plant, growing in a site where density has been reduced by previous wildfires, may produce as much seed as 1,000 plants growing on the same unit of area in an adjacent unburned site. The successful management of B. tectorum infested ranges is dependent on establishing a perennial grass. The characteristics of the individual site infested with the invasive grass determines the steps necessary to return dominance to perennial species.