Project Number: 5370-11220-006-08
Project Type: Reimbursable

Start Date: Jul 01, 2009
End Date: Sep 30, 2012

Objective:
To investigae(1) potential for Great Basin native annual forbs to effectively compete with cheatgrass and (2) the relative establishment success of native perennial grasses in native annual forbs vs. in cheatgrass. The Ultimate goal of the work is to determine whether it would be useful to include native annuals in postfire rehabilitation seed mixes.

Approach:
Buried seed bank experiments for Amsinckia tesselata, Amsinckia intermedia, Mentzelia albicalus, and Bromus tectorum will be used to provide more detailed information about the dormancy status and germination requirements of three aggressive native annuals in relation to cheatgrass and to do so under field conditions. I will use a buried seed bank experiment and temperature dataloggers to determine the extent and duration of seedbank carryover and temperatures of germination in the field. This study will provide information about the timing and conditions for germination in these native annuals and cheatgrass. A greenhouse experiment will be used to determine whether competitive dynamics between Amsinckia tesselata and Bromus tectorum depend on water or nutrient availability. We will plant small-diameter greenhouse tubes with combinations of cheatgrass and Amsinckia. The competition experimental design will include 3 levels of nutrients and 3 of soil moisture. This experiment will help us determine whether Amsinckia can compete with cheatgrass at lower water levels and higher nutrient levels, two of the more challenging restoration situations. To complement the greenhouse experiment we will perform a field removal experiment to look at competition between Amsinckia and cheatgrass. This study will be performed at 3 replicate sites in western Nevada. We will look at the effects of different levels of neighbor removal on 3 target plants: Amsinckia, cheatgrass, and Elymus elymoides. This experiment will provide information on competition at the establishment stage under field conditions and will allow us to quantify the success of a native perennial grass in stands of native annuals versus in cheatgrass. Each of 10 native annuals will be screened for competitive ability with cheatgrass. The goal of this study will be to determine which species are most competitive with cheatgrass. This experiment will be completed during the funding period. This greenhouse screening will be followed up with a field experiment in future years. A field study will be used to look at demography of Amsinckia intermedia and cheatgrass at a single site. Data will be used to address the following questions: (a) For each species, do adult densities and seed output predict seed bank densities? (b) What kind of precipitation years favor native annuals? (c) What kind of precipitation years favor cheatgrass? [7/09:Documents Reimbursable Agreement with Forest Service. Log 39905.]