Electronic Theses and Dissertations

Title

The Effects of Ecological Restoration on Soil Microbial Enzyme Activities and Leaf Litter Decomposition

Date of Award

2010

Document Type

Dissertation

Degree Name

M.S. in Biological Science

First Advisor

Colin R. Jackson

Second Advisor

Clifford A. Ochs

Third Advisor

Stephen Brewer

Abstract

This study examined the immediate effects of ecological restoration on soil enzyme activities and decomposition. The activities of five enzymes: phosphatase, ?-glucosidase, ?-N-acetylglucosadminidase (NAGase), phenol oxidase, and lignin-peroxidase were measured in both soils and on decomposing Quercus falcata leaf litter in unburned, burned, and burned and thinned plots in a mesic forest in northern Mississippi. Rates of decomposition were also assessed for Q. falcata leaf litter at each plot. The restoration treatments decreased phosphatase activity in relation to an increase in soil organic matter after the fire, and increased NAGase activity in relation to a decrease in leaf litter after the fire. Activities of extracellular enzymes associated with decomposing Q. falcata leaf litter in litterbags showed no consistent patterns amongst treatments or between individual enzymes. Decomposition of Q. falcata leaf litter was slightly accelerated in the treatment plots; however, decay rates were not significantly different from each other. Decomposition was related to cumulative enzyme activity, with phenol oxidase and peroxidase having the highest apparent efficiencies in degrading this material. When the activity of all enzymes was combined, the microbial degradation of Q. falcata leaf litter was more efficient in the burned frequently and thinned, and burned and thinned plots than in the other treated plots. The combination of burning and thinning can further a restoration project by reducing the amount of litter through both a reduction in inputs and more efficient decomposition of litter material. This reduction in the litter layer could allow for increased solar penetration to the soil, and could allow the shade-intolerant species that once dominated the understory to proliferate.

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