2013 Annual Report
1a.Objectives (from AD-416):
The University of Nevada at Reno is undertaking a cooperative project with the Agricultural Research Service and to investigate (1) the ability of key Great Basin native annual species to compete with cheatgrass as well as (2) their ability to facilitate the establishment of Great Basin native perennial bunchgrasses. The ultimate goal of this project is to assess the suitability of key Great Basin native annual species for use in restoration seedings.
1b.Approach (from AD-416):
The University of Nevada at Reno will assist in developing, implementing, and analyzing experiments to assess the ability of Great Basin native forb species to compete with cheatgrass and facilitate establishment of native perennial grasses. This will include collaborating with ARS on greenhouse and field experiments, as well as the writing of scientific manuscripts.
This is the final report for this project which was terminated on December 1, 2012. This agreement is established in support of objective 4 of the in-house project, "Develop restoration methodologies to prevent the invasion of annual grasses (such as cheatgrass, medusahead rye, and/or red brome) following destructive events (such as fire) in rangeland ecosystems".
In arid systems, facilitation may be an important component of vegetation recovery after disturbance. Establishment of native perennial species in disturbed western rangelands is desirable, but is severely limited by the presence of the highly competitive exotic annual grass, cheatgrass (Bromus tectorum). Greater restoration success may be achieved with seed mixes that mimic natural succession in Great Basin systems, which include native annuals as a key component of the post-disturbance community. Due to overlapping phenology, there is the potential for strong competitive interactions between native and exotic annuals, which could indirectly facilitate establishment of perennial species.
The objectives of this study were to (1) Determine the effect of select native annual forbs on the performance of cheatgrass and big squirreltail (Elymus multisetus) under field and greenhouse conditions and (2) Determine if the presence of native annual forbs increases the performance of big squirreltail when grown with cheatgrass.
In greenhouse and field experiments, seedlings of a native perennial grass, big squirreltail, were grown individually with each of five native annual forbs (bristly fiddleneck [Amsinckia tesselata], common fiddlehead [A. intermedia], Veatch’s blazingstar [Mentzelia veatchiana], rough eyelashweed [Blephariappus scaber], and western tansymustard [Descurania pinnata]) and with an annual forb mix (bristly fiddleneck, Veatch’s blazingstar, wingnut cryptantha [Cryptantha pterocarya], and Great Basin woollystar [Eriastrum sparsiflorum]). Half of the replicates were seeded with cheatgrass. We recorded the number of green leaves on big squirreltail plants after planting to assess treatment effects on growth rate and measured aboveground biomass of big squirreltail and neighboring plants after one growing season. Additionally, cheatgrass was grown with native annuals in the greenhouse and field to determine the effect of native annual forbs on cheatgrass biomass and seed production. Structural equation modeling (SEM) was also used to examine the direct and indirect effects of native annual forbs on big squirreltail performance under greenhouse and field conditions.
Bristly fiddleneck and common fiddleneck were the most competitive native annuals with Cheatgrass, suppressing biomass and seed production more than other forb species. In the greenhouse, big squirreltail growth and seasonal biomass production were lower when grown with cheatgrass than with any of the native annuals. Additionally, when in competition with cheatgrass, big squirreltail’s growth performance was best when Veatch’s blazingstar was also present, and growth rates were significantly greater when any of the annual forbs were also present. Although bristly fiddleneck was beneficial to big squirreltail in the greenhouse, under field conditions, the fiddleneck had a negative effect on the squirreltail performance. However, over time, these negative effects decreased and could potentially lead to facilitation of big squirreltail later in the season because of it’s perennial habitat and longer growing season.