Date of Award

2020

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Biological Sciences (PhD)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Casey J Huckins

Committee Member 1

Amy M Marcarelli

Committee Member 2

Joseph W Wagenbrenner

Committee Member 3

Troy G Zorn

Abstract

The relationships between wood and streambed substrates, among other abiotic components, are complex and an important part of the arrangement and dynamics of habitat in forested stream ecosystems. The objective of this research was to expand how we approach the study of the physical components of forested streams by considering the methods used to quantify these features, particularly substrates. Additionally, we assessed the temporal change over 14 years for streambed substrates, channel morphology, and large wood in a selectively-logged watershed. Our final objective was to understand if a relationship exists between the complexity of streambed morphology derived from variograms, and volume of instream large wood in forested streams. Our results suggest that Structure from Motion photogrammetry is a suitable complement or alternative to pebble counts for quantifying submerged streambed substrate composition as well as temporal changes in streambed morphology at small spatial scales (chapter 2). We determined the volume and abundance of large wood decreased within streams located in selectively logged catchments over the 14 years, but that the stability in streambed substrates and channel morphology did not appear relate to the amount of wood present (chapter 3). Finally, we found that in these tributaries of the Otter River, channel complexity metrics developed from variograms were not related to the volume of large wood present in stream channels (chapter 4). We hypothesize that may be due to the relatively low volume of wood compared to western US streams in addition to wood being too small relative to the local channel and larger landscape features, and that other underlying factors may be driving morphological complexity in these stream channels. Together, this research demonstrates that the association between large wood and channel complexity may not apply to all forested streams, and highlights some of the complexity in understanding the spatial and temporal relationships in forested streams, as well as presents an innovative approach to quantifying and monitoring streambed substrates and morphology.

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