Master's Theses

Date of Award

Summer 1960

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Committee Chair

Abstract

This investigation was an attempt to determine the seasonal development and seed production of the major grasses in areas which had been subjected to different intensities of grazing in past years. The grasses used in this study were (1) buffalo grass (Buchloe dactyloides); (2) blue grama (Bouteloua gracilis); (3) side- oats grama (B. curtipendula); (4) western wheatgrass (Agropyron smithii); (5) little bluestem (Andropogon scoparius); and (6) big bluestem (A. gerardi). Exclosures were established on upland and hillside sites of three pastures which were classified accordingly with past history of grazing as follows: (1) non- grazed; (2) moderately grazed; and (3) heavily grazed. Precipitation was the primary limiting factor in this study. For two years preceding the investigation rainfall had been above normal. During the growing season of 1959, when this study was conducted, two mid-season droughts occurred. After establishing exclosures in the grazed locations to prevent grazing, individual plants of each major species were designated to be measured and sketched weekly. Measurements recorded or calculated can be separated into five main categories as follows: (1) basal cover and composition; (2) weekly and cumulative height and length of leaves of each marked plant (verified by general notes); (3) seasonal forage yields; (4) number of tillers producing inflorescences; and (S) yield of caryopses. Findings were as follows: (1) Basal cover of grasses increased with grazing, but less desirable species became more abundant. (2) Big bluestem was the latest major grass to initiate growth and did not begin until April 28; whereas, all others had started growth by April 1. (3) Blue grama flowered first and produced the greatest percentage of inflorescences in the heavily grazed location. (4) Western wheatgrass was greatly affected by drought and development of this species was poor in all areas. (5) Big and little bluestem were apparently affected most by grazing, and development of these species in the non- grazed prairie preceded the grazed locations. (6) Development of side-oats grama varied only slightly under the different intensities of grazing. (7) Forage production in the non-grazed location consistently yielded more than the moderately grazed pasture and produced nearly twice as much as the area heavily grazed. (8) The number of tillers producing inflorescences varied considerably with degree of grazing. Little bluestem and side-oats grama produced the greatest number of flower stalks in the non- grazed prairie; whereas, big bluestem, blue grama and western wheatgrass produced the greatest number in the heavily grazed area. (9) Yield of caryopses was poor for all species except hairy grama (Bouteloua hirsuta). Big and little bluestem produced no caryopses in the heavily grazed location. Side-oats grama, blue grams, and western wheatgrass produced the greatest number of caryopses under heavily grazed conditions. Results of the various studies were also presented and illustrated by tables, figures and photographs.

Rights

Copyright 1960 Marlyn V. Jones

Comments

Notice: This material may be protected by copyright law (Title 17 U.S. Code).

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