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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 202 for “"headwater"”.
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Logging impacts the ecology of molecules in headwater streams
… 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, …
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Headwater stream network connectivity: biogeochemical consequences and carbon fate
Headwaters may be small relative to other aquatic ecosystems, but they are neither simple nor static environments. Heterogeneous stream corridors constitute the majority of river network length and regulate cycling of carbon and oxygen as they expand and contract their connections across the …
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Linking Heterotrophic Metabolism and Nutrient Uptake in Headwater Streams
… level. We address how nutrient demand in headwater streams changes with shifts in organic matter supply and associated microbial activity by investigating these relationships in the predominantly heterotrophic conditions of a southern Appalachian stream. We measured litter input, organic …
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Modeling Intermittent and Perennial Headwater Stream Origins In North Carolina.
<p>Low-order headwater streams, a link between the upland landscape and larger streams within a watershed, affect watershed hydrology. Yet current widely available maps inadequately depict headwater streams, underestimating channel length or omitting channels entirely. Intermittent and perennial …
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Effects of forest disturbance on shredder production in headwater streams
Effects of forest disturbance on leaf shredding aquatic insects were investigated by comparing leaf biomass and shredder production in disturbed versus reference forest streams. Benthic samples were collected monthly in 3 streams in a mature hardwood reference forest and 3 streams in an 11-year-old …
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Determining primary drivers of river bead functionality in mountain headwater streams
I evaluated flux attenuation potential, or functionality, in laterally extensive storage-dominated reaches known as 'beads.' Beads are disproportionately important to river corridor health. Bead functionality was evaluated as a relationship between driver variables, which directly measure or …
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Temporal Dynamics of Groundwater Flow Direction in a Glaciated, Headwater Catchment
… groundwater flow in the critical zone of steep headwater mountain catchments is often assumed to mimic surface topography. However, groundwater flow is influenced by other variables, such as the elevation of the water table and subsurface hydraulic conductivity, which can result in temporal …
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Effect of Spatial Scale on Hydrologic Modeling in a Headwater Catchment
… mountainous Back Creek catchment, located in the headwaters of the Roanoke River in Southwest Virginia. The two models employed were HEC-1, an event based lumped model, and TOPMODEL, a continuous semi-distributed model. These models were used to investigate (a) the issue of spatial scale in …
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Measuring and Understanding Effects of Prescribed Fire in a Headwater Catchment
Headwater catchments play a large role in the storage and release of water and chemical constituents, thereby influencing downstream flows and water quality. Recent advances in water quality monitoring technologies have created an opportunity to better assess water chemistry variation by using high …
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Livestock Exclusion Effects on the Structure and Function of Headwater Streams
The structure and function of headwater streams was evaluated in response to livestock exclusion implemented through Virginia's Conservation Reserve Enhancement Program (CREP). We measured riparian plant characteristics along with stream organic matter dynamics, benthic macroinvertebrates, algal …
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Effects of experimentally-altered hydrology on ecosystem function in headwater streams
Forested headwater stream ecosystems are important integrators of terrestrial and aquatic systems and their function depends greatly on water availability. In the southern Appalachians, models of future climate change predict alterations to the timing and intensity of storms such that most …
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Headwater Stream Biofilm Structure and Function at High Resolution Spatial-temporal Scales.
… investigated over a 25 month period within three headwater sub-catchments of the River Eden catchment, NW England. This was undertaken as structural and functional attributes of headwater stream have at large been neglected, despite the long-standing recognition of the importance of …
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Quantifying Solute and Water Fluxes in Headwater Streams Using Passive Flux Meters
… were deployed in the surface and subsurface of headwater stream channels to examine the efficacy of the device to quantify mean concentrations of calcium, aluminum, and sulfur in streams of the Hubbard Brook Experimental Forest in New Hampshire, USA. In general, the PFM estimates of surface and …
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Denitrification in sediments of headwater streams in the southern Appalachian Mountains, USA
We investigated variations in resource availability (nitrate and labile organic carbon, LOC) as determinants of denitrification in sediments of streams in the southern Appalachian Mountains, USA. Stream water and sediments were sampled seasonally in two streams of contrasting nitrate availability, …
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Characterization of dissolved fluvial carbon from landscape characteristics across High Arctic headwater streams
… of the stream network through a watershed. Small headwater streams in the High Arctic are understudied and account for a significant amount of the freshwater geochemical flux from North America. This research investigates the concentration of fluvial dissolved organic carbon (DOC) and dissolved …
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Sample Collection and DNA Extraction Methods for Environmental DNA Metabarcoding in Headwater Streams
<p>DNA is found to be free and ubiquitous in the environment where it is no longer associated with the source organism, and is also known as environmental-DNA (eDNA). Methods optimized for specific environments may be able supplement insight to local taxa richness. With the advent of high …
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Community ecology of aquatic insects in forested headwater streams in the southern Appalachians
… processes for benthic macroinvertebrates in headwater streams in the southern Appalachians. Distance decay in taxonomic and functional similarity was used to determine the scales at which taxonomic turnover occurred within functional niches. Trait-neutral models of community composition were …
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