Date of Award:

5-2009

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Ecology

Committee Chair(s)

Matthew E. Baker

Committee

Matthew E. Baker

Committee

Tamao Kasahara

Committee

Bethany T. Neilson

Abstract

The ability of riparian buffers to filter undesirable nutrients from upland sources has long been recognized as an important ecosystem service for maintaining or improving water quality, and as a result, many land management strategies have been built around the preservation or restoration of buffer zones. Newly derived flow-path metrics have shown great promise as a way to assess riparian buffer function at the watershed scale but a thorough investigation of metric performance was necessary. The goals of this study were to: 1) test the independence of flow-path metrics from traditional metrics using a spatially extensive, independent sample of watersheds, 2) evaluate the effects of stream map resolution on riparian characterization and the ability to predict nitrate discharges, and 3) explore whether nutrient retention estimates may improve the performance of flow-path metrics. The results of this study validated initial findings that flow-path metrics provided more flexible, detailed, and independent measures of land cover patterns compared to traditional methods. Buffer characterization by flow-path metrics was affected by stream map resolution, as were models using metrics to relate nitrate discharge to watershed land cover patterns. Retention-informed metrics showed promise in improving the ability to relate nitrate-nitrogen discharges to measures of riparian function, especially in certain physiographic contexts. A thorough understanding of flow-path metrics and how they are affected by sampling regime, stream map resolution, and estimates of retention is necessary toward the development of a tool useful to land use managers.

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