Date of Award

5-1-2003

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Biology

First Advisor

Dr. Thomas Bragg

Abstract

The effect fire season and frequency was evaluated in 2001 at a 65 ha restored tallgrass prairie in eastern Nebraska using permanent plots established in 1978 and first evaluated in 1979. Treatments included annual and quadrennial burning in spring, summer, and fall as well as unburned plots. Overall, the number of species increased from 28 in 1979 to 30 in 2001, with a shift from ruderal to native species. Shannon diversity (H’) increased significantly across all treatments during this time. Canopy cover of grasses (+19%) and forbs (+18%) increased significantly. However, only forbs showed a significant difference among treatments in 2001 with the lowest value occurring in the annual spring treatment (6%) and the highest value occurring in the annual variable-season treatment (35%). The canopy cover of individual species showed varying responses to treatment. Native perennial grasses, such as big bluestem (Adropogon gerardii) and Indiangrass (Sorghastrum nutans), generally increased with more frequent burning, although there was considerable variation among seasonal treatments. Cool-season native sedges (Carex spp.) also increased significantly with quadrennial burns but remained low or absent with frequent fire, irrespective of season. The response of forb species differed from that of grasses in that higher cover generally occurred with less frequent burning, or with annual fall or variable-season burning. This study suggests that variation in fire season and frequency in the tallgrass prairie has the potential to affect diversity, species composition, species groups, and individual species. Overall, this study shows that fire management with different seasons and frequencies of burning can be used to maintain prairie diversity. More specifically, varying plant responses suggest that fire management should be applied with a more random and less systematic season and frequency than is typically applied in prescribed burning of tallgrass prairies in order to maximize diversity.

Comments

A Thesis Presented to the Department of Biology and the Faculty of the Graduate College University of Nebraska In Partial Fulfillment of the Requirements for the Degree Master of Arts University of Nebraska at Omaha. Copyright 2003 Nathaniel David Birks.

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