Thesis advisor: Noah P. Snyder / Thesis advisor: Gail C. Kineke / Maine coastal rivers host the last remaining runs of endangered anadromous Atlantic salmon in the United States, whose populations have decline from ~500,000 returning adults in the 1880s to only ~1000 in 2000. Restoration projects have focused on these coastal river systems to bring natural populations back to the area, and recent efforts involve adding large woody debris (LWD) to small tributaries to improve salmon rearing habitat. Large woody debris actively changes the hydraulics and geomorphology of small streams by acting as a barrier to flow and creating decreased velocity zones, scour pools, and sediment storage and sorting. I study the effects of LWD additions in early August 2008 on hydraulics and substrate in Baker Brook, a west-flowing tributary of the Narraguagus River. Hydraulically, I focus on the treatment reach nearest the confluence with the Narraguagus River (Baker1), and I also study changes in substrate in Baker1 and the upstream treatment location (Baker3). Both study locations are divided into two reaches, treatment (Baker1-T and Baker3-T) and control (Baker1-C and Baker3-C). In Baker1, the treatment and control reaches are further divided into four 50 m sub-reaches based on channel gradient (~1% in Baker1-C-Flat and Baker1-T-Flat; >2% in Baker1-C-Steep and Baker1-T-Steep). In Baker3, we use two 50 m sub-reaches of similar gradient (ranges from ~1% to 2%) to determine substrate changes. Significant post-LWD addition changes are determined by comparison with the control sub-reaches. Changes in the treatment sub-reaches must be larger than those in the control sub-reaches to be deemed significant. I seek to answer three research questions: (1) how much does mean velocity through the study sub-reaches change as a result of additions; (2) how much does hydraulic roughness change; and (3) does sediment storage and spatial sorting result from the LWD additions? I measured reach-average velocities (Ureach) in Baker1 using the salt dilution method in May, July and August 2008 and May 2009. I use rating curves to compare the post-treatment to the pre-treatment Ureach-stage relationship. A temporary decrease in Ureach occurred in October 2008 in Baker1-T-Flat, whereas the other sub-reaches experienced no change in Ureach. A localized change in cross-sectionally averaged velocity (U) measured with a flow meter, is also evident at Baker1-T-Flat, but this is because an added tree lies directly in the downstream cross-section where measurements are recorded. I assessed channel roughness changes by comparing roughness rating curves created using the Manning roughness parameter, n (back-calculated from velocity measurements) for each sub-reach. Because of the short-term decrease in Ureach, roughness increased in Baker1-T-Flat in October 2008 as well. No change in roughness is evident in the other sub-reaches because post-treatment values of n plot on the same decreasing trend with respect to stage as pre-treatment values. I quantified pre- and post-treatment sub-reach substrate median grain size (D50) with intensive clast counts in July 2008 and May 2009. In Baker1, analysis of pre-treatment substrate size show that the flat sub-reaches have a finer substrate size (34-38 mm) than the steep sub-reaches (88-134 mm). Baker3 pre-treatment grain size is similar to that of the flat Baker1 sub-reaches, with a median grain size of 38 mm in Baker3-T and 28 mm in Baker3-C. Two of the three treatment sub-reaches exhibited significant fining (D50 decreased by 37-54%) between the surveys, and the third changed less than measurement uncertainty. One of the three control sub-reaches coarsened significantly (D50 increased by 29%), one fined significantly (-42%), and one coarsened less than measurement uncertainty. In summary, I find that LWD additions in Baker Brook had little effect on reach-scale hydraulics during the flows we observed, but did influence bed-grain size during the 10-month study interval, underscoring the importance of floods on channel change. / Thesis (MS) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

Previous research on coarse woody debris (CWD) indicated that moisture content and initial heterotrophic colonization of decaying wood can affect the decomposition process. Six heterotrophic treatments were created to simulate the effects of physical penetration of the bark and wood and the transmission of ascomycetes versus basidiomycetes into CWD. In 1995, 360 Douglas-fir (Pseudotsuga menziesii) were randomly placed at five replicate sites in old-growth stands. Each site had 6 heterotrophic (HET) x 2 moisture combinations (TENT). One set of logs representing the treatment combinations was used for sampling respiration and another set was used to measure volume affected by insect gallery excavations and fungal rot and to determine decay rates. Respiration was sampled three times during the summer of 2001. The results indicated that the HET treatments were no longer affecting respiration rates. Analysis of the average of the three sampling periods revealed no TENT effect but examinations of the individual sampling dates suggests that tented logs might have higher respiration rates than non-tented logs as summer progresses. In the aggregate, the TENT treatment reduced moisture content from 45% to 36%, a 20 percent reduction in moisture levels. The HET and the TENT treatments did not affect decay rates. The mean density change for the logs was -0.072 g/cm�� �� 0.03 and the mean decay constant was 0.026 �� 0.011. The TENT treatment did affect heterotrophic activity. The mean volume of wood borer excavation and extent of brown rot was higher in the tented logs (256 cm��) than in the non-tented logs (59.9 cm��). There was also a statistically significant interaction between the HET and TENT treatments. The largest differences in volume affected by wood borers and fungal rot were found in treatments that injected ascomycetes into the experimental logs. In sum, there was limited evidence that the differences in moisture content caused by the TENT treatment affected the decomposition process but the HET treatments appear to not be directly influencing decomposition after six years. The findings suggest differences in the initial community composition of heterotrophs have a decreasing impact on the decomposition process as it progresses. / Graduation date: 2004

Forest floor calcium (Ca) declines in northern hardwood forests are of interest because Ca availability may limit future forest growth. In the 1990s investigations into Ca pools and fluxes across a northern hardwood forest chronosequence showed decreases across stand age in the mass of forest floor base cations and litterfall cation concentrations. I undertook a study of factors that influence litterfall chemistry to develop a better understanding of base cation biogeochemistry in developing northern hardwood forests. Although Ca, potassium (K), and magnesium (Mg) concentrations in litterfall significantly declined with stand age, species composition and soil nutrient availability also influenced litterfall chemistry. The interplay between these factors, such as the distribution of species with different nutrient demands in areas of base cation availability or limitation, influences forest floor chemistry and may impact the time in which soil Ca depletion occurs. Additionally, I examined the quantity and qualities (species composition, decay class, size, and nutrient concentrations and contents) of woody debris across the same northern hardwood forest chronosequence. The objectives of this study were to quantify cation pools in woody debris, describe how the qualities of these woody debris pools change with stand development, and establish a baseline for long-term measurements of woody debris accumulation and chemistry with stand age. Decomposition of woody debris transfers base cations to the forest floor, and may be partially responsible for forest floor Ca gains in young stands. Calcium and K pools in woody debris were most strongly influenced by woody debris biomass, whereas Mg content was influenced by both woody debris biomass and species composition. In young stands, woody debris pools were strongly influenced by management practices during harvest. By 20 years since harvest woody debris pools reflected processes of stand development. For example, from 20 to nearly 40 years since harvest woody debris biomass and species composition was dominated by mortality of early successional species. Woody debris in more mature stands reflected small-scale stochastic disturbances including disease and single-tree mortality. Litterfall and woody debris are each components of within-stand cation cycling that will be critical to future forest growth with limited Ca availability.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2008. / Includes reprints of four papers and manuscripts co-authored with others. Includes bibliographical references. Also partially available electronically via World Wide Web in PDF format; online version lacks reprints of four papers and manuscripts.

Thesis (M.S.)--Oregon State University, 1995. / Typescript (photocopy). Includes bibliographical references (leaves 78-83). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1991. / Typescript (photocopy). Includes bibliographical references (leaves 84-90). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 85-93).

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2006. / Includes bibliographical references (leaves 96-105).

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 60-63). Also available on the World Wide Web.

The extreme flooding event that occurred in 2013 in Alberta, Canada was at time the most costly natural hazard event in the nation’s history with damages exceeding $5 billion. Due to this event, an increased effort for flood mitigation strategies began and resulted in the proposal of the Springbank Off-Stream Storage Reservoir to divert and detain Elbow River flow upstream of the City of Calgary. In order to validate the design of the flow diversion structures, a large (1:16) scale physical model was constructed. The model tested among other things, the impact of large woody debris (LWD) on the flow diversion structures. The LWD modelling included a comparison of LWD manufactured from smooth cylindrical dowels versus natural tree limbs of the same dimensions. The results from the physical model led to a series of design changes for the diversion structures that likely would not have been identified without physical modelling. The LWD material comparison demonstrated significantly different behaviours between LWD types. Specifically, LWD manufactured from natural tree limbs was significantly more likely to accumulate in debris dams on the diversion structures. The impact of root wad was also investigated and proved to play a major role in the damming characteristics and blocking probability of debris. Following the physical model investigations, a numerical simulation was completed in order to examine further the hydrodynamic results obtained from the Springbank project. Using TELEMAC MASCARET’s open source free surface flow program TELEMAC 2D, a two dimensional simulation was completed using data from the physical model. Flowrates and velocities from both models were compared and discrepancies between the two are identified. Reasoning for these differences as well as future works for the numerical model are presented.