Logging impacts the ecology of molecules in headwater streams
type: CreativeWork
description: Forest management and harvest offer a promising means of combating climate change by removing CO2 from the atmosphere. However, most forest carbon (C) is held in soils. Thus, by disturbing soils and altering hydrology, forest management and harvest potentially displace large amounts of C from forest soils into aquatic ecosystems. My dissertation seeks to understand the fate of this forest C as dissolved organic matter (DOM) into various aquatic endpoints by tracing its molecular composition along the ephemeral water film that begins in upland soils and ends in streams. The fate and function of DOM in aquatic ecosystems are strongly affected by its chemical properties. Thus, recent progress in the molecular characterization of DOM has opened a new line of inquiry into harvest impacts on aquatic ecosystem functioning. My thesis advances this line of inquiry by applying high-resolution mass spectrometry to study the effect of forest disturbance on DOM in soils and connected streams. Chapter 1 of this thesis gives a general overview of the molecular nature of terrestrial DOM sources, how these sources may be altered by harvest, and the subsequent transfer, fate, and properties of DOM once in streams. It also outlines the specific objectives I address with a combination of field experiments and synoptic surveys in the Batchewana watershed in Ontario, Canada. In Chapter 2, I tracked DOM along soil depths, and hillslope positions in four replicate forest headwater catchments of the Canadian hardwood forest. I related DOM composition to soil microbiomes and physical chemistry to establish baseline conditions before a harvest experiment. I found that DOM changed similarly along soil-aquatic gradients, irrespective of differences in environmental conditions. My results implicated continuous microbial reworking that shifts DOM towards a shared pool of compounds in soils. Such general degradation patterns can inform the management of soil-to-stream carbon losses by predicting D…
abstract: Forest management and harvest offer a promising means of combating climate change by removing CO2 from the atmosphere. However, most forest carbon (C) is held in soils. Thus, by disturbing soils and altering hydrology, forest management and harvest potentially displace large amounts of C from forest soils into aquatic ecosystems. My dissertation seeks to understand the fate of this forest C as dissolved organic matter (DOM) into various aquatic endpoints by tracing its molecular composition along the ephemeral water film that begins in upland soils and ends in streams. The fate and function of DOM in aquatic ecosystems are strongly affected by its chemical properties. Thus, recent progress in the molecular characterization of DOM has opened a new line of inquiry into harvest impacts on aquatic ecosystem functioning. My thesis advances this line of inquiry by applying high-resolution mass spectrometry to study the effect of forest disturbance on DOM in soils and connected streams. Chapter 1 of this thesis gives a general overview of the molecular nature of terrestrial DOM sources, how these sources may be altered by harvest, and the subsequent transfer, fate, and properties of DOM once in streams. It also outlines the specific objectives I address with a combination of field experiments and synoptic surveys in the Batchewana watershed in Ontario, Canada. In Chapter 2, I tracked DOM along soil depths, and hillslope positions in four replicate forest headwater catchments of the Canadian hardwood forest. I related DOM composition to soil microbiomes and physical chemistry to establish baseline conditions before a harvest experiment. I found that DOM changed similarly along soil-aquatic gradients, irrespective of differences in environmental conditions. My results implicated continuous microbial reworking that shifts DOM towards a shared pool of compounds in soils. Such general degradation patterns can inform the management of soil-to-stream carbon losses by predicting D…
author: Freeman, Erika
language: eng
keywords: carbon cycling, dissolved organic matter, forestry
license: https://www.repository.cam.ac.uk/bitstreams/e9157708-d250-4f52-9d1e-7a03941d8162/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2023-01-16
date modified: 2026-07-24T01:33:21Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.104251