Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 2005
Publication Date: February 12, 2006
Citation: Young, J.A., Clements, C.D. 2006. Phenology of invasive annual weeds in downy brome communities [abstract]. Proceedings Weed Science Society of America. February 12-17, 2006, New York, New York. 46:120. Technical Abstract: Downy brome (Bromus tectorum) has invaded millions of acres of formerly big sagebrush (Artemisia tridentata)/bunchgrass rangeland in western North America. Downy brome dominance truncates succession by eliminating the recruitment of seedlings of native perennial species. Downy brome communities are often referred to as monocultures, but once disturbed these annual dominated communities form a seral continuum of some 40 exotic species. We investigated the phenology of 24 of these species in an experiment conducted outdoors at Reno, Nevada. Seeds of each accession were planted in 60 liter pots filled with a biologically sterile soil derived from decomposed granite. The pots were arranged in a randomized block design with 4 replications. The pots were watered uniformly daily through the course of the experiment. Each pot was seeded with 25 seeds and replicated 4 times with the assigned species on November 1, 2004. Data was collected weekly on seedling emergence and subsequent phenological development until maturity. Surface soil temperatures were measured daily at 8:00 AM, 12:00 noon, and 4:00 PM. Despite air temperatures well below freezing, all seedlings of small seeded false flax (Camelina microcarpa) were emerged after 1 week. The first species to mature seeds was bur buttercup (Ranunculus testiculatus) where all plants had finished their life cycle by mid March. Halogeton (Halogeton glomeratus) was the last species to mature. Downy brome matured in June with marked variation among accessions of the species. Downy brome plants matured in early summer despite ideal soil moisture conditions. The interplay among species in phenology provides insight on a variety of life strategies that permits coexistence on the same site in seral sequence and for some species in the same seral time sequence.