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Document Type

Thesis - University Access Only

Award Date

2015

Degree Name

Master of Science (MS)

Department

Natural Resource Management

First Advisor

Lora Perkins

Abstract

Variation in precipitation and drought in mixed grass and tallgrass prairies effects vegetative production for cool season and warm season plants. Ranchers and farmers livelihoods are dependent on adequate annual precipitation and vegetation for cattle production. Historically, in South Dakota drought has occurred in northern mixed grass prairie one out of five years. Cottonwood Range and Livestock Research Station data (Western South Dakota) demonstrated occurrence of spring drought 29% and summer drought 25% of years between 1909-2005. My thesis objectives were to determine management history and spring or summer drought resistance on vegetation production in 1) northern mixed grass prairie; and 2) tallgrass prairie. Stationary rainout shelters were deployed to simulate 50% spring or summer rainfall reduction. 2-yr and 1-yr spring (April-June) and summer (June-August) drought regimes were used to measure resistance in 2014 and 2015 of aboveground biomass in two contrasting plant communities (high productivity/high diversity, low productivity/low diversity) on three ranches (Oacoma, Highmore, and White River) in mixed grass prairie of SD. Tallgrass prairie precipitation treatments, 50% summer drought, ambient (actual rainfall), and 130% normal (30-year average)) were achieved using stationary rainout shelters on areas with different management histories (annual fire, annual mowing, and undisturbed control (no management)) near Volga SD. We tested effects of drought on aboveground plant total and proportion of functional group biomass to total biomass in 2014 and 2015. Aboveground clippings collected in 2014 and 2015 at the end of the growing season showed total biomass and proportion of total biomass for both the mixed grass and tallgrass prairie to be similar among treatments. Management history, but not variation in precipitation, influenced proportion of native warm season versus proportion of introduced cool season grasses. Annual fire and annual mowing plots produced higher proportion of native warm season grasses and lower amounts of cool season grasses compared with undisturbed control. These results suggest that plants in the mixed grass and tallgrass prairies are not affected by two-year manipulations of precipitation.

Description

Includes bibliographical references (pages 83-99)

Format

application/pdf

Number of Pages

110

Publisher

South Dakota State University

Rights

Copyright © 2015 Joe Bennett

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