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Title: Characteristics that determine a successful squirreltail (Elymus elymoides)

item Harmon, Daniel - Dan
item Clements, Darin - Charlie

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2014
Publication Date: 1/31/2015
Citation: Harmon, D.N., Clements, D.D. 2015. Characteristics that determine a successful squirreltail (Elymus elymoides). In: Society for Range Management Meeting Abstracts, January 31-February 6, 2015. 68:46.

Interpretive Summary:

Technical Abstract: The successful rehabilitation of degraded cheatgrass (Bromus tectorum) dominated Wyoming Big sagebrush (Artemisia tridentata spp. Wyomingensis) communities hinge on the establishment of long-lived perennial grasses. While we have been successful with using introduced perennial grasses (i.e. Siberian wheatgrass) for rehabilitation efforts leading to cheatgrass suppression, decreased wildfire frequencies and succession towards grass/shrub co-dominance, the need for maintaining native populations of perennial grasses still exists. Seeding native grasses in the Great Basin has largely been ineffective and developing improved germplasm has been a research priority for decades. Research limitations are the criteria by which “improved” has been defined. Most improvements (i.e. forage production) rely on an assumption of establishment. This research examines how “improvements” relate to establishment. Bottlebrush squirreltail is a native perennial grass that has been studied extensively for rangeland rehabilitation potential. Squirreltail is a good candidate for plant material development because of phenotypic variation and known hybridization. However, it does have its limitations for cultivation such as large awns and lower seed yields. The Agricultural Research Service has conducted extensive research on the genetics and ecology of Elymus elymoides and related species, releasing numerous germplasms for rehabilitation use. To date we have had little rehabilitation success with squirreltail germplasm releases. In 2009, we began searching for squirreltail populations in degraded Wyoming sagebrush rangelands of the northwestern Great Basin from some of the most difficult rehabilitation habitats. By 2011, we identified 3 unique phenotypes in which each phenotype was selected from a field site where it exhibited good productivity and some degree of weed suppression along with desirable characteristics for arid land survival. Most of the desirable traits were similar to Dr. Tom Jones’ (Forage and Range Research Lab) traits for distinguishing ecological accessions. Based on our field rehabilitation seeding experience we hypothesized seedling success based on the observed traits ranking as Type 1 (vigor), Type 2 (cold germination) and Type 3 (leaf morphology). Type 1 exhibits rapid seedling growth and pubescent leaves. The pubescence gives this phenotype a silvery appearance similar to sagebrush with water saving pubescent leaf surfaces. Type 2 exhibits colder temperature germination, a characteristic attributed to the success of cheatgrass and other fall/winter germinating weeds. Type 3 exhibits a small leave surface almost needle-like, similar to drought tolerant needle grasses. While seedling drought survival is a trait linked to the most successful rehabilitation grasses (i.e. crested wheatgrass (Agropyron cristatum), the type 3 squirreltail along with a drought tolerant leaf morphology had very poor seedling vigor similar to needle grasses. This led us to rank it third in our hypothesis. To test this hypothesis we seeded the 3 phenotypes along with a popular release germplasm ‘Toejam’ at five sites (8” precipitation) and designed a common garden soil box test to reduce external field variables. Field studies indicated that Type 1 and 3 were similarly successful. Soil boxes determined Type 1 the most successful, partially supporting our hypothesis. All three phenotypes established well above the cultivated ‘Toejam’ and within the range of providing cheatgrass suppression (Type 1- 9.64 plants/m², Type 2- 9.43 plants/m², Type 3- 7.71 plants/m² and ‘Toejam’ – 0.36 plants/m²). While these results are promising, establishment was based on first-year July seedling counts in which continued die-off can be expected. The true test of success is the sustainability of plant densities and future seedling recruitment. Native grasses should have comp