Date of Award:

5-2016

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Committee Chair(s)

J. Earl Creech

Committee

J. Earl Creech

Committee

Kevin B. Jensen

Committee

Eric T. Thacker

Abstract

The choice of plant materials is an important factor in restoration or revegetation of disturbed rangelands. To better identify plant materials that could be adapted to increased competition from invasive grasses and fluctuations in temperature and precipitation, there is a need to understand potential seedling establishment, plant persistence, and dry-matter yield (DMY) as a measure of plant vigor in the newly developed varieties across a wide range of environmental conditions. Experiments were conducted on four semiarid range sites to compare these traits in 14 perennial cool-season grass species currently used for revegetation in the Western U.S.A. There were location differences, with overall seedling establishment ranging from 28 to 70% seedling frequency at Malta, ID and Tintic, UT sites, respectively. No one species was statistically highest for seedling frequency at all four locations. However, there were four species that had higher seedling frequency at three of the four locations: Siberian wheatgrass (Agropyron fragile [Roth] Candargy), crested wheatgrass (Agropyron cristatum [L.] Gaertn), and (Agropyron desertorum [Fish. ex Link] J. A. Schultes), intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D.R. Dewey) and Snake River wheatgrass (Elymus wawawaiensis J. Carlson & Barkworth). The newer varieties, in most instances, had increased seedling frequency vs. older varieties. Intermediate wheatgrass had the highest dry matter yields (DMY) at the Beaver location while crested and Siberian wheatgrass were highest for DMY at the Cheyenne location. Plant frequency was evaluated every year for five years after planting to determine stand persistence. Trends in plant persistence showed that, although difficult to establish, stands of western wheatgrass increased in the years after establishment due to rhizome development. Slender wheatgrass had a negative linear trend in stand persistence at the four tested locations. These results can help land managers make informed decisions concerning the choice of plant materials for revegetation projects, as related to potential seedling establishment, stand persistence, and relative biomass production.

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