Date of Award

2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Wildland Resources

First Advisor

Scott B. Jones

Abstract

Cheatgrass, a widespread invasive plant, has taken over many rangelands in the Intermountain West. Restoration efforts have not met with much success. Early in cheatgrass’ growth period, if air temperatures fall too low and soils too dry, growth may be disrupted to the point of death of the cheatgrass plants. In this case, cheatgrass stands may revert to bare ground, providing opportunities for other invasive plants to establish, or possible restoration of native perennials. We conducted a computer modeling and observational field study to determine if air temperature and soil moisture conditions below its tolerance are associated with failure of cheatgrass stands. We found that a combination of dry soil conditions in the cheatgrass rooting zone in fall 2007 and cool spring temperature in spring 2008 provided at least a partial explanation for the reversion of cheatgrass to bare ground in spring 2008. Available soil moisture and nutrient resources left unused by cheatgrass failure represent an opportunity for restoration or exploitation by additional invasive species. Conditions leading to invasion of cheatgrass by other invasive species may represent the best conditions for restoration to native perennial vegetation.

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