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United States Department of Agriculture

Agricultural Research Service

Research Project: Investigations of Seed and Seeding Ecology and Competitive Ability of Native Annual Forbs of the Western Great Basin

Location: Great Basin Rangelands Research

Project Number: 2060-22000-023-07
Project Type: Reimbursable

Start Date: Feb 02, 2011
End Date: Sep 30, 2015

Objective:
To investigate (1) the potential for Great Basin native annual forbs to effectively compete with B. tectorum and facilitate the establishment success of native perennial grasses (2) the germination ecology of key Great Basin native annual forbs. The ultimate goal of this work is to determine whether it would be useful to include native annuals in postfire rehabilitation seed mixes.

Approach:
1. Greenhouse competition study: This aspect of the research is being conducted in combination with scientists at UNR. We have completed one greenhouse experiment to look at competition of the two native species with B. tectorum and establishment of E. multisetus with native annual forbs, with B. tectorum , and with annual forb-B. tectorum mix. Growing with competitors decreased the size of E. multisetus, however the largest decrease in size was found when grown with B. tectorum and A. tesselata. In contrast, E. multisetus grew best with M. veatchiana. When in competition with B. tectorum, E. multisetus performed best when M. veatchiana was also present. These results support the idea that the presence of certain native annual forbs can enhance the establishment of E. multisetus in B. tectorum invaded rangelands. 2. Buried seed bank experiments for Amsinckia tesselata, Amsinckia intermedia, Blepharipappus scaber, and Mentzelia veatchiana: For each species, I prepared artificial seed bank buried bags. Bags are being retrieved monthly for one year, then in early spring and late summer for up to 5 years or until there is no evidence of seed carryover. For each bag, the number of recently field-germinated seeds, seeds germinable at 2/15°C for 4 weeks are being determined. 3. Field study: Amsincka intermedia and Bromus tectorum demography. I have collected three years of demographic data quantifying plant density and seed output for B. tectorum and Amsinckia intermedia at a field site. We will resample the plots and add seed bank sampling to determine how long-term fluctuations in adult and seed bank densities relate to amount and timing of precipitation for the native and the invasive annual. 4. Field competition study: This experiment also is being conducted in combination with two scientists at UNR. Last fall, we planted small plots with combinations of native annuals and Bromus tectorum. The experiment looks at the performance of B. tectorum or E. multisetus target plants in annual native forb monocultures, B. tectorum monoculture, or a mixture of annual native forbs and B. tectorum.

Last Modified: 11/26/2014
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