Date of Award:

1975

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Ecology

Advisor/Chair:

Neil E. West

Abstract

Aboveground biomass, litter biomass and root biomass of a crested wheatrgrass (Agropyron desertorum [Fisch.] Schult.) dominated community were inventoried in the fall of 1971, 1972, and 1973. In addition, energy, nitrogen, fats and ash determinations were made on the materials collected in 1972 and 1973.

The sampling methods used generated data sufficiently precise to detect significant differences (α = .10) among biomass components among years. The chemical contents of the components were similar in the fall of 1972 and the fall of 1973 despite the large differences in growing season precipitation.

A simple linear regression formula was generated from which aboveground biomass was predicted using individual plant volume as the independent variable. Regression techniques were tried in an effort to use aboveground biomass to predict root and litter biomass. This approach proved unsuccessful because of high variability within the data.

Changes in the biomass of the components were analyzed with respect to differing precipitation regimes. Aboveground biomass responded positively and linearly to increasing growing season precipitation. Litter biomass decreased as current growing season precipitation increased. However, litter increased as a function of increasing previous-growing-season precipitation. Root biomass decreased with increasing previous-growing-season precipitation. It was found that both litter:shoot and root:shoot ratios decreased as a function of increasing growing season precipitation.

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