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Author: Claire Marie Ruffing Publisher: ISBN: Category : Languages : en Pages :
Book Description
Geomorphic properties of streams are linked to ecosystem function through processes related to storage, transport, and other drivers regulating biogeochemical conditions. Disturbances altering the physical template of a stream are associated with cascading impacts on ecosystem function. However, few disturbances are studied at long time scales and so the legacy of such events and the implications for ecosystem structure and function are not well understood. This research investigates the role of historic tie-driving, a channel disturbance legacy, in shaping present-day stream channel conditions in the Rocky Mountain region and the associated implications for organic matter dynamics. Using a combination of geomorphic and riparian surveys, organic matter and vegetation sampling, and modeling, I show that components of mountain stream ecosystems have recovered from tie-driving at varying rates. First, I addressed how tie-driving has altered channel morphology and wood loading. Tie-driven streams are narrower, shallower, less rough, and have less wood than non-driven reference reaches. In a second study, I focused on differences in carbon storage within the stream and riparian area between tie-driven and non-driven streams. Carbon stored on the landscape represents a long-term component of the terrestrial carbon cycle and some, but not all, components have been impacted by tie-driving. Large instream wood, coarse downed wood, and fine downed wood were identified as carbon storage components that were significantly smaller in tie-driven stream-riparian corridors. Finally, I modeled whole stream ecosystem metabolism and tested whether abiotic drivers influenced variations in rates of gross primary productivity (GPP), ecosystem respiration (ER), and net ecosystem productivity (NEP). Results from this work suggest that rates of GPP were significantly different between tie-driven and non-driven streams and were partially explained by variations in light related to canopy structure. However, variations in ER and NEP were not significantly different between tie-driven and non-driven sites. Taken as a whole, this work shows that ecosystems bear the imprint of historic disturbances but individual ecosystem components recover at differing rates. Additionally, integrating stream hydro-geomorphic and ecological dynamics is an effective approach to understanding the impact of channel disturbances in shaping ecosystem function at a variety of spatial and temporal scales.
Author: Claire Marie Ruffing Publisher: ISBN: Category : Languages : en Pages :
Book Description
Geomorphic properties of streams are linked to ecosystem function through processes related to storage, transport, and other drivers regulating biogeochemical conditions. Disturbances altering the physical template of a stream are associated with cascading impacts on ecosystem function. However, few disturbances are studied at long time scales and so the legacy of such events and the implications for ecosystem structure and function are not well understood. This research investigates the role of historic tie-driving, a channel disturbance legacy, in shaping present-day stream channel conditions in the Rocky Mountain region and the associated implications for organic matter dynamics. Using a combination of geomorphic and riparian surveys, organic matter and vegetation sampling, and modeling, I show that components of mountain stream ecosystems have recovered from tie-driving at varying rates. First, I addressed how tie-driving has altered channel morphology and wood loading. Tie-driven streams are narrower, shallower, less rough, and have less wood than non-driven reference reaches. In a second study, I focused on differences in carbon storage within the stream and riparian area between tie-driven and non-driven streams. Carbon stored on the landscape represents a long-term component of the terrestrial carbon cycle and some, but not all, components have been impacted by tie-driving. Large instream wood, coarse downed wood, and fine downed wood were identified as carbon storage components that were significantly smaller in tie-driven stream-riparian corridors. Finally, I modeled whole stream ecosystem metabolism and tested whether abiotic drivers influenced variations in rates of gross primary productivity (GPP), ecosystem respiration (ER), and net ecosystem productivity (NEP). Results from this work suggest that rates of GPP were significantly different between tie-driven and non-driven streams and were partially explained by variations in light related to canopy structure. However, variations in ER and NEP were not significantly different between tie-driven and non-driven sites. Taken as a whole, this work shows that ecosystems bear the imprint of historic disturbances but individual ecosystem components recover at differing rates. Additionally, integrating stream hydro-geomorphic and ecological dynamics is an effective approach to understanding the impact of channel disturbances in shaping ecosystem function at a variety of spatial and temporal scales.
Author: Keli J. Goodman Publisher: ISBN: Category : Languages : en Pages : 183
Book Description
This research combines observation, experimentation, and modeling to evaluate the influence of lakes on dissolved organic matter (DOM) quantity, quality and export in subalpine watersheds of the Sawtooth Mountain Lake District, central Idaho. First, I conducted an empirical study of the hydrologic and biogeochemical controls on DOM dynamics in stream-lake fluvial networks. I hypothesized that lakes would decrease temporal variability (i.e., buffer) and alter the characteristics of DOM from inflow to outflow. I tested these hypotheses by evaluating DOM temporal patterns and measuring annual export in seven-paired lake inflows and outflows. I then evaluated how ultraviolet (UV) exposure affected DOM characteristics during snowmelt and baseflow, and how UV alters baseflow DOM bioavailability and nutrient limitation. Given that increased water residence time increases UV exposure, I hypothesized that lake outflow DOM would be more photorecalcitrant than DOM from lake inflows. I further hypothesized that UV exposure would increase DOM quality, heterotrophic processing, and nutrient demand. Results indicate that lakes can buffer stream temporal variability by acting as a DOM sink during snowmelt and a DOM source during baseflow. Lake outflow DOM photodegradation was similar to lake inflows during snowmelt (p=0.66). Conversely, outflow DOM was 2X more photorecalcitrant than inflow DOM during baseflow (ANOVA, p=0.03) and was strongly related to water residence time (WRT). During baseflow, light exposure increased inflow and outflow DOM bioavailability (p=0.059 and 0.024, respectively) and nutrient limitation (p=0.03 and 0.09, respectively). Combined, these results indicate that WRT in subalpine lakes strongly influences DOM temporal variability and DOM degradation and processing. Thus, lakes can provide temporal stability of DOM and potentially increase both carbon and nutrient uptake by heterotrophs in lake outflows. I then evaluated how global changes could alter hydrologic and nutrient dynamics in a subalpine lake. Model results indicate that the magnitude and timing of snowmelt runoff can have a substantial effect on water and nutrient exports. In phosphorus (P)- limited lakes, increases in inorganic N concentrations within and exported from lakes are likely to occur with increased temperatures and lake WRT. Increases in atmospheric N deposition will further enhance inorganic N exports in P-limited subalpine lakes.
Author: Jonathan A. Czuba Publisher: U.S. Department of the Interior, U.S. Geological Survey ISBN: Category : Languages : en Pages : 150
Book Description
A study of the geomorphology of rivers draining Mount Rainier, Washington, was completed to identify sources of sediment to the river network; to identify important processes in the sediment delivery system; to assess current sediment loads in rivers draining Mount Rainier; to evaluate if there were trends in streamflow or sediment load since the early 20th century; and to assess how rates of sedimentation might continue into the future using published climate-change scenarios. Rivers draining Mount Rainier carry heavy sediment loads sourced primarily from the volcano that cause acute aggradation in deposition reaches as far away as the Puget Lowland. Calculated yields ranged from 2,000 tonnes per square kilometer per year [(tonnes/km2)/yr] on the upper Nisqually River to 350 (tonnes/km2)/yr on the lower Puyallup River, notably larger than sediment yields of 50–200 (tonnes/km2)/yr typical for other Cascade Range rivers. These rivers can be assumed to be in a general state of sediment surplus. As a result, future aggradation rates will be largely influenced by the underlying hydrology carrying sediment downstream. The active-channel width of rivers directly draining Mount Rainier in 2009, used as a proxy for sediment released from Mount Rainier, changed little between 1965 and 1994 reflecting a climatic period that was relatively quiet hydrogeomorphically. From 1994 to 2009, a marked increase in geomorphic disturbance caused the active channels in many river reaches to widen. Comparing active-channel widths of glacier-draining rivers in 2009 to the distance of glacier retreat between 1913 and 1994 showed no correlation, suggesting that geomorphic disturbance in river reaches directly downstream of glaciers is not strongly governed by the degree of glacial retreat. In contrast, there was a correlation between active-channel width and the percentage of superglacier debris mantling the glacier, as measured in 1971. A conceptual model of sediment delivery processes from the mountain indicates that rockfalls, glaciers, debris flows, and main-stem flooding act sequentially to deliver sediment from Mount Rainier to river reaches in the Puget Lowland over decadal time scales. Greater-than-normal runoff was associated with cool phases of the Pacific Decadal Oscillation. Streamflow-gaging station data from four unregulated rivers directly draining Mount Rainier indicated no statistically significant trends of increasing peak flows over the course of the 20th century. The total sediment load of the upper Nisqually River from 1945 to 2011 was determined to be 1,200,000±180,000 tonnes/yr. The suspended-sediment load in the lower Puyallup River at Puyallup, Washington, was 860,000±300,000 tonnes/yr between 1978 and 1994, but the long-term load for the Puyallup River likely is about 1,000,000±400,000 tonnes/yr. Using a coarse-resolution bedload transport relation, the long-term average bedload was estimated to be about 30,000 tonnes/yr in the lower White River near Auburn, Washington, which was four times greater than bedload in the Puyallup River and an order of magnitude greater than bedload in the Carbon River. Analyses indicate a general increase in the sediment loads in Mount Rainier rivers in the 1990s and 2000s relative to the time period from the 1960s to 1980s. Data are insufficient, however, to determine definitively if post-1990 increases in sediment production and transport from Mount Rainier represent a statistically significant increase relative to sediment-load values typical from Mount Rainier during the entire 20th century. One-dimensional river-hydraulic and sediment-transport models simulated the entrainment, transport, attrition, and deposition of bed material. Simulations showed that bed-material loads were largest for the Nisqually River and smallest for the Carbon River. The models were used to simulate how increases in sediment supply to rivers transport through the river systems and affect lowland reaches. For each simulation, the input sediment pulse evolved through a combination of translation, dispersion, and attrition as it moved downstream. The characteristic transport times for the median sediment-size pulse to arrive downstream for the Nisqually, Carbon, Puyallup, and White Rivers were approximately 70, 300, 80, and 60 years, respectively.
Author: Heather Bonin Publisher: ISBN: Category : Sedimentation and deposition Languages : en Pages : 156
Book Description
Allochthonous litter inputs are a primary source of organic matter in low-order forested streams. A major component of this litter moves through small streams as fine particulate organic matter (FPOM). Litter decomposition has been well studied, but few studies have examined benthic FPOM (FBOM) dynamics. The purpose of this study was to investigate, (1) how FBOM is controlled by headwater vegetation, elevation and seasons, (2) the links between organic matter inputs and FBOM substrate quality and (3) the relationships between FBOM substrate quality and microdecomposer activity. In preparation for this study, the stability of various microbial and chemical characteristics of FBOM during storage and analysis was determined. Denitrification potential (DNJT), phosphatase activity (PHOS), and extractable ammonium (EA) remained stable over a minimum of 11 hours of storage at 5°C. Mineralizable N (NMIN), respiration (RESP) rates, and [beta]-glucosidase (BGLC) activity all decreased within 12 hours of collection. Results varied for nitrogen fixation (NFIX). In response to these results, our laboratory protocol was altered to accommodate analyses with varying levels of stability. Following this protocol, FBOM was sampled and analyzed over a 10 month period from 14 first-order streams in the Cascade Mountains of western Oregon. Streams ran through forests in three successional age classes: old-growth forest (OG) dominated by Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla), and young regenerating stands (YS) either 10 years old, with a large riparian herbaceous component, or 30 years old, surrounded by deciduous trees such as red alder (Alnus rubra). Decreases in C:N, CTOT, NTOT and organic P (PORG) were mirrored by reciprocal increases in FBOM RESP, BGLC, PHOS and NFIX, all relative indicators of microbial activity. The lower C:N and higher DNIT, RESP, BGLC, PHOS, and NMJN observed in YS FBOM compared with OG suggests higher quality FBOM and faster decomposition rates in YS FBOM. Seasonal trends showed a major autumn deflection in FBOM C:N ratios and microbial activities, a likely result of increased leaf inputs following an early fall storm. Significantly lower C:N at high elevation (1220-1280 m) suggested the presence of more herbaceous vegetation and alder in high elevation riparian zones. Lower NTOT and CTOT and elevated DNIT, NFIX, RESP, PHOS at low elevation (580-800 m) suggested greater decomposition rates at low elevations. PORG was 2.2 and 3.6 mg P gOM1 at high and low elevations respectively, a difference (p
Author: Kirk Fraser Hawthorn Publisher: ISBN: Category : Eutrophication Languages : en Pages : 116
Book Description
Headwater streams in Alberta's Rocky Mountains are important in regulating aquatic ecosystem function and a range of downstream water resources but are vulnerable to stresses imposed by disturbances including those exerted by logging. The objectives of this research were to determine if the legacy of past forest harvesting impacts could be detected in altered sediment-nutrient dynamics and primary productivity in headwaters in the Rocky Mountains of southwestern Alberta. A descriptive, process-based case study was conducted in an undisturbed-disturbed watershed pair where one watershed had undergone extensive harvesting ending in 1990. The disturbed watershed was found to have higher concentrations of suspended solids and fine streambed material, and considerably greater levels of aqueous and particulate phosphorus (P). Primary productivity was much higher in the disturbed system, likely caused by elevated P levels. This study illustrates the potential for logging disturbance to produce long-lived impacts on stream ecology in critical headwater regions.
Author: National Research Council Publisher: National Academies Press ISBN: 0309082951 Category : Science Languages : en Pages : 449
Book Description
The Clean Water Act (CWA) requires that wetlands be protected from degradation because of their important ecological functions including maintenance of high water quality and provision of fish and wildlife habitat. However, this protection generally does not encompass riparian areasâ€"the lands bordering rivers and lakesâ€"even though they often provide the same functions as wetlands. Growing recognition of the similarities in wetland and riparian area functioning and the differences in their legal protection led the NRC in 1999 to undertake a study of riparian areas, which has culminated in Riparian Areas: Functioning and Strategies for Management. The report is intended to heighten awareness of riparian areas commensurate with their ecological and societal values. The primary conclusion is that, because riparian areas perform a disproportionate number of biological and physical functions on a unit area basis, restoration of riparian functions along America's waterbodies should be a national goal.
Author: Hannah E. Harris Publisher: ISBN: Category : Languages : en Pages : 162
Book Description
The effects of disturbance may propagate through river networks via changes in fluxes of materials and organisms. I investigated how two natural disturbances, wildfire and subsequent debris flows, altered fluxes of invertebrates and organic matter from tributaries in the South Fork Salmon River Basin of central Idaho, USA. I compared export of invertebrates through drift and insect emergence from tributaries with different disturbance histories (5 unburned, 5 burned in 2007, and 5 burned in 2007 + subsequent debris flow in 2008). Also, I compared selection ratios of fish for confluence habitats between tributaries with differing disturbance histories and abundance of riparian spiders along tributaries with differing disturbance histories. Downstream fluxes of invertebrate biomass to the mainstem river were 3-4x higher from burned + debris flow streams than from unburned streams. Fish selected for confluence habitats and most strongly for those with disturbed tributaries. Fish also exhibited higher rates of agonistic behaviors in confluence areas compared with similar habitats that did not receive inputs from a tributary, indicating that confluences may be worth defending. Biomass of emerging- aquatic insects and spider abundance did not significantly differ between streams with different disturbance histories. Burned + debris flow streams exported organic matter of higher quality and proportionally more r-strategist invertebrates than unburned streams. Increased exports of resources from burned + debris flow tributaries to mainstem rivers may enhance the productivity of the recipient habitat and benefit organisms such as driftfeeding fish. These potential positive effects may work to partially offset the episodic negative effects of downstream sedimentation following debris flows.
Author: Claire Marie Ruffing
Author: Claire Marie Ruffing
Author: Joan L. Florsheim
Author: Keli J. Goodman
Author: Jonathan A. Czuba
Author: Heather Bonin
Author: Kirk Fraser Hawthorn
Author: National Research Council
Author: William Kevin Pierson
Author: Vijay P. Singh
Author: Hannah E. Harris