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ARS Home » Pacific West Area » Pullman, Washington » Plant Germplasm Introduction and Testing Research » Research » Publications at this Location » Publication #340271
Title: Genecology of Thurber’s needlegrass (Achnatherum thurberianum (Piper) Barkworth) in the Western United States

Author
item JOHNSON, R.C. - Retired ARS Employee
item LEDGER, E.A. - University Of Nevada
item VANCE-BOURLAND, KEN - The Conservation Planning Institute, Inc

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2017
Publication Date: 7/1/2017
Citation: Johnson, R., Ledger, E., Vance-Bourland, K. 2017. Genecology of Thurber’s needlegrass (Achnatherum thurberianum (Piper) Barkworth) in the Western United States. Rangeland Ecology and Management. 70:509-517. https://doi.org/10.1016/j.rama.2017.01.004.
DOI: https://doi.org/10.1016/j.rama.2017.01.004

Interpretive Summary: Land managers are challenged to identify populations for large-scale restoration projects that are adapted and ecologically suited over diverse regions. In this study 12 seed zones were developed to guide restoration for Thurber’s needlegrass based on the relationship between genetic variation in common gardens and seed source climates. There was a strong link between climate and key plant traits suggesting climate driven evolution and adaptation. Since only six seed zones represented 90% of the mapped area, seed production of populations by zone would be practical even though large scale seed processing would be complicated by the typically long awns of this species. The seed zones should be open to revision and modification consistent with future research, climate change, and local knowledge of Thurber’s needle grass adaptation. Still, they provide a research based framework for selecting Thurber’s needlegrass seed sources for restoration projects over much of the intermountain Western U.S.

Technical Abstract: Thurber’s needlegrass (Achnatherum thurberianum (Piper) Barkworth) is a key restoration species in the Great Basin and surrounding areas, yet comprehensive studies of how climate relates to genetic variation and seed zones for restoration projects are lacking. Potentially adaptive phenotypic traits of 66 diverse populations of Thurber’s needlegrass were measured in common gardens at Central Ferry WA, and Reno, NV in 2012 and 2013. Extensive genetic variation was observed among phenology, morphology, and production traits (P<0.01) and canonical correlation was used to relate traits to source climate variables. Only with the first two canonical variates were F values significant (P<0.05), explaining 42% and 18% of the variation, respectively. For variates 1 and 2, strong canonical correlations of 0.97 and 0.94 linked genetic variation with source climates, providing evidence for climate-driven evolution. Pearson linear correlations indicated that populations from warmer, dryer locations generally had earlier blooming and longer awns than those from cooler, wetter locations. Plants from warmer, dryer locations also had higher survival at Central Ferry and higher leaf length to width (narrower leaves) at Reno in 2012. Regression of the canonical variates 1 and 2 for traits with source climate variables produced very strong models, explaining 94% and 87% of the variation in plant traits. These models were used to map 12 seed zones encompassing 465,079 km2 in the Great Basin and surrounding areas with six seed zones representing 90% of the mapped area. We recommend using these seed zones to guide restoration of Thurber’s needlegrass.