Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Life Sciences
Spatial Heterogeneity Of Nitrogen Cycling Within And Across Freshwater Ecosystems, Erin K. Eberhard
Spatial Heterogeneity Of Nitrogen Cycling Within And Across Freshwater Ecosystems, Erin K. Eberhard
Dissertations, Master's Theses and Master's Reports
Dinitrogen (N2) fixation and denitrification are two nitrogen (N) cycling processes that despite differences in environmental requirements and constraints, co-occur in aquatic ecosystems. The overall goal of this dissertation was to evaluate how spatial heterogeneity of environmental variables 1) drive hot spots of N2 fixation, denitrification rates and gene abundances in streams, 2) facilitate co-occurrence of these processes across wetland – stream – lake interfaces, and 3) affect differences in microbial community composition in streams across U.S. ecoregions. We found hot spots of both processes within 7 stream reaches in Michigan and Idaho, but rates of N …
Controls On Autotrophic Respiration, Heterotrophic Respiration, And Decomposition In Northern Forested Rivers, Renn Schipper
Controls On Autotrophic Respiration, Heterotrophic Respiration, And Decomposition In Northern Forested Rivers, Renn Schipper
Dissertations, Master's Theses and Master's Reports
Autotrophic respiration (AR), heterotrophic respiration (HR), and decomposition are important contributors to the carbon cycle in streams. It is important to understand how different environmental factors, such as canopy cover and dissolved organic carbon (DOC), influence these processes. DOC concentrations in northern forested streams are increasing, which may affect light and carbon availability. To examine the effects of DOC and canopy cover on these processes we measured gross primary production, ecosystem respiration and decomposition at 8 sites in 4 streams in the Upper Peninsula of Michigan and used quantile regression to estimate AR and HR. Among sites, AR and decomposition …