Date of Award

12-1981

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Botany

First Advisor

Jack B. Wade

Second Advisor

Lawrence A. Dyde

Third Advisor

James E. Schindher

Abstract

This study at Coweeta Hydrologic Laboratory in the southern Appalachian Mountains of North Carolina used two watersheds at experimental ecosystems. Based on the assumption that streams, especially small-order streams draining upland deciduous forests, cannot be considered systems which are independent of their watersheds, this study under took to describe the effect that perturbation of the watershed would have on streams and, in particular, stream flora. The algal and bryophyte flora of streams draining experimental and control watersheds were studied to determine the reponse of stream flora to watershed perturbation. A clear-cut was used to remove the living terrestrial flora from the experimental watershed. Subsequent monitoring showed increased light availabilty and dissolved ion concentrations in the experimental stream in comparison with the control stream. However, algal growth in the experimental stream as limited to assemblages associated with pre-existing mosses. These moss-associated algal assemblagges may have arisen from population growth or from stream sediments which also accumulated among the pre-existing mosses. This accumlation of algae and sediments was an agent of nutrient retention among these moss associations. Carbon assimilation rates showed increased primary production among both the mosses and the sediment-associated algae which accumulated among the mosses. However, these relatively high rates of assimilation may not apply to the whole area of the stream; hence, compaison of annual carbon budgets must be made with this condition. Moreover, this study showed the importance of physical factors to the maintenance and functioning of stream systems. Scouring due to seiment transport limited the growth of periphyton on exposed rock surfaces but contributed to the accumulation of algal ceels and particulate nutrients amoung pre-existing mosses. Steam mosses provided sites of low current velocity and thus functioned as agents of sediment and algal accumulation.

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