Date of Award

Fall 12-1-2003

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Geography, Geology, and Anthropology

First Advisor

James H. Speer

Second Advisor

Ryan R. Jensen

Third Advisor

Stephen F. Wolf

Abstract

The Indiana Department of Natural Resources estimates that fire-maintained, tallgrass savannas once covered approximately 15% oflndiana. During the 1800's, settlers cleared savannas for their rich soils, which are well suited for agricultural use, and fire was suppressed from the remaining savannas because of the threat to farmland. Today, prescribed bums are being used in savannas as a management tool to reduce competition from non-native species, encourage community density, and promote patch dynamics. This research examines how fire affects Cation Exchange Capacity (CEC) in post fire soil samples. CEC is an important soil characteristic that helps to describe soil fertility. With high CEC, soil fertility is increased and more nutrients become available for plant growth. lll Thirty pre bum samples and 229 post bum samples (up to 40 samples, two times a week, for three weeks) were collected during the spring bum season from Hoosier Prairie Nature Preserve, Indiana. These samples were taken using a 30.5 em soil sampling tube with a two centimeter diameter at a depth from one to five centimeters. Samples were processed and analyzed to identify and quantify major individual cations and total CEC. CEC and individual cation concentrations, excluding Aland Na, were found to show an overall declining trend after the April23, 2003 bum. There was a solitary increase around sampling round 4 (May 2, 2003). This increase was attributed to the incorporation of ash into the soil by a precipitation event. After round 4, the values again declined throughout the sampling. The overall decline in CEC might be attributed to the removal of organic exchange sites which were present during the pre bum sampling round. Various factors resulted in the overall decline of cation concentrations: nutrient exportation (convective transportation, percolation, or wind erosion), removal of exchange sites, differing vegetation types, or lag time between burns. Each of these factors needs more in-depth exploration before one factor or a combination of them can be attributed to the decline. Although the overall cation and CEC values decline and data do not show any conclusive results for the decline, it does illustrate the need for continuing research. The methods used in this research offer opportunities to environmental managers to examine related issues on their fire managed areas. With further research, many of the variables which affect soils and vegetation after prescribed or natural fires can be managed to enhance the natural ecosystem.

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