<p class=MsoNormal><span style="mso-spacerun: yes">?????????????????? </span>Stable isotopic analysis of nitrate (¹⁵N/¹⁴N and ¹⁸O/¹⁶O) was used to trace nitrate sources and cycling under undisturbed conditions and following harvest at the Turkey Lakes Watershed (TLW), located near Sault Ste. Marie, Ontario, Canada. <span style="mso-spacerun: yes">?? </span> <p class=MsoNormal><span style="mso-spacerun: yes">?????? </span><span style="mso-spacerun: yes">????????????</span>Bulk precipitation collected biweekly at the TLW from 1995 to 2000 had nitrate isotope values that ranged from +42. 4 to +80. 4&permil; for <span style='font-family:Symbol'>d</span>¹⁸O and -6. 3 to +2. 8&permil; for <span style='font-family:Symbol'>d</span>¹⁵N. <span style="mso-spacerun: yes">?? </span>An incubation experiment indicated that the isotopic composition of atmospheric nitrate was not compromised by collection methods whereby unfiltered bulk precipitation samples remain in the collector for up to two weeks. <span style="mso-spacerun: yes">?? </span> <p class=MsoNormal><span style="mso-spacerun: yes">?????????????????? </span>The first direct measurement of the isotopic composition of microbial nitrate produced <i>in situ</i> was obtained by eliminating precipitation inputs to three forest floor lysimeters and subsequently watering the area with a nitrate-free solution. <span style="mso-spacerun: yes">?? </span>Microbial nitrate had <span style='font-family:Symbol'>d</span>¹⁸O values that ranged from +3. 1 to +10. 1&permil; with a mean value of +5. 2&permil;, only slightly higher than values predicted based on the <span style='font-family:Symbol'>d</span>¹⁸O-H₂O of the watering solution used. <span style="mso-spacerun: yes">?? </span><span style='font-family:Symbol'>d</span>¹⁸O values of soil O₂ (+23. 2 to +24. 1&permil;) down to a depth of 55cm were not significantly different from atmospheric O₂ (+23. 5&permil;) and therefore respiratory enrichment of soil O₂ did not affect the <span style='font-family:Symbol'>d</span>¹⁸O values of microbial nitrate produced at the TLW. <span style="mso-spacerun: yes">?? </span> <p class=MsoNormal><span style="mso-spacerun: yes">?????????????????? </span>Nitrate export from two undisturbed first-order stream basins was dominated by microbial nitrate, with the contribution of atmospheric nitrate peaking at about 30% during snowmelt. <span style="mso-spacerun: yes">?? </span>Clear-cutting of catchment 31 in 1997 resulted in elevated nitrate concentrations, reaching levels that exceeded the drinking water limit of 10 mg N/L. <span style="mso-spacerun: yes">?? </span>Isotopic analysis indicated that the source of this nitrate was predominantly chemolithoautotrophic nitrification. <span style="mso-spacerun: yes">?? </span>The <span style='font-family:Symbol'>d</span>¹⁸O values of microbial nitrate in stream 31 progressively increased during the post-harvest period due to an increase in the proportion of nitrification that occurred in the summer months. <span style="mso-spacerun: yes">?? </span>Despite drastic alteration of nitrogen cycling in the catchment by the harvest, <span style='font-family:Symbol'>d</span>¹⁵N-nitrate values in shallow groundwater did not change from the pre-harvest. <span style="mso-spacerun: yes">???? </span>Denitrification and plant uptake of nitrate in a small forested swamp in catchment 31 attenuated 65 to 100% of surface water nitrate inputs following harvest, reducing catchment-scale nitrate export by 35 to 80%.

<p class=MsoNormal><span style="mso-spacerun: yes">          </span>Stable isotopic analysis of nitrate (¹⁵N/¹⁴N and ¹⁸O/¹⁶O) was used to trace nitrate sources and cycling under undisturbed conditions and following harvest at the Turkey Lakes Watershed (TLW), located near Sault Ste. Marie, Ontario, Canada. <span style="mso-spacerun: yes">  </span> <p class=MsoNormal><span style="mso-spacerun: yes">    </span><span style="mso-spacerun: yes">      </span>Bulk precipitation collected biweekly at the TLW from 1995 to 2000 had nitrate isotope values that ranged from +42. 4 to +80. 4&permil; for <span style='font-family:Symbol'>d</span>¹⁸O and -6. 3 to +2. 8&permil; for <span style='font-family:Symbol'>d</span>¹⁵N. <span style="mso-spacerun: yes">  </span>An incubation experiment indicated that the isotopic composition of atmospheric nitrate was not compromised by collection methods whereby unfiltered bulk precipitation samples remain in the collector for up to two weeks. <span style="mso-spacerun: yes">  </span> <p class=MsoNormal><span style="mso-spacerun: yes">          </span>The first direct measurement of the isotopic composition of microbial nitrate produced <i>in situ</i> was obtained by eliminating precipitation inputs to three forest floor lysimeters and subsequently watering the area with a nitrate-free solution. <span style="mso-spacerun: yes">  </span>Microbial nitrate had <span style='font-family:Symbol'>d</span>¹⁸O values that ranged from +3. 1 to +10. 1&permil; with a mean value of +5. 2&permil;, only slightly higher than values predicted based on the <span style='font-family:Symbol'>d</span>¹⁸O-H₂O of the watering solution used. <span style="mso-spacerun: yes">  </span><span style='font-family:Symbol'>d</span>¹⁸O values of soil O₂ (+23. 2 to +24. 1&permil;) down to a depth of 55cm were not significantly different from atmospheric O₂ (+23. 5&permil;) and therefore respiratory enrichment of soil O₂ did not affect the <span style='font-family:Symbol'>d</span>¹⁸O values of microbial nitrate produced at the TLW. <span style="mso-spacerun: yes">  </span> <p class=MsoNormal><span style="mso-spacerun: yes">          </span>Nitrate export from two undisturbed first-order stream basins was dominated by microbial nitrate, with the contribution of atmospheric nitrate peaking at about 30% during snowmelt. <span style="mso-spacerun: yes">  </span>Clear-cutting of catchment 31 in 1997 resulted in elevated nitrate concentrations, reaching levels that exceeded the drinking water limit of 10 mg N/L. <span style="mso-spacerun: yes">  </span>Isotopic analysis indicated that the source of this nitrate was predominantly chemolithoautotrophic nitrification. <span style="mso-spacerun: yes">  </span>The <span style='font-family:Symbol'>d</span>¹⁸O values of microbial nitrate in stream 31 progressively increased during the post-harvest period due to an increase in the proportion of nitrification that occurred in the summer months. <span style="mso-spacerun: yes">  </span>Despite drastic alteration of nitrogen cycling in the catchment by the harvest, <span style='font-family:Symbol'>d</span>¹⁵N-nitrate values in shallow groundwater did not change from the pre-harvest. <span style="mso-spacerun: yes">   </span>Denitrification and plant uptake of nitrate in a small forested swamp in catchment 31 attenuated 65 to 100% of surface water nitrate inputs following harvest, reducing catchment-scale nitrate export by 35 to 80%.

Streamside management zones (SMZs) have become important management techniques to prevent the introduction of sediment to stream networks. This study examined the current Kentucky best management practice (BMP) guidelines for SMZs by outfitting mobile forest harvest equipment with global positioning system (GPS) receivers, enabling modeling of equipment traffic and spatial analysis of stream sediment delivery. Three SMZ configurations were implemented during commercial timber harvest, along with four different techniques of crossing ephemeral channels, in order to determine where and why sediment was introduced to the stream network. Results indicate that increasing the SMZ buffer width leads to decreased sediment delivery, and that requiring an SMZ buffer with some canopy retention on ephemeral channels will lead to improvements in stream water quality. Care should be taken in the placement and construction of water control measures for skid trail retirement, and improved stream channel crossings such as bridges and pipe culverts should be required to improve water quality over unimproved fords. A northeasterly aspect of harvested areas was shown to be related to increased sediment delivery to streams, while surface roughness downslope from the skid trail system was shown to decrease sediment delivery.

Forest harvesting has been shown to cause various changes in water quantity and water quality parameters, highlighting the need for comprehensive forest practice rules. Studies show a myriad of impacts to ecosystems as a result of watershed level changes, such as forest harvesting. Being able to better understand the impact that forest harvesting can have on stream temperature is especially critical in locations where federally threatened or endangered fish species are located. The overall goal of this research project is to assess responses in stream temperature to various riparian and forest harvest treatments in a maritime, mountainous environment. The results of this study aim to inform decision makers with additional information pertaining to the effects of forest harvest on water temperature. Modeling is done as a part of the third Caspar Creek Paired Experimental Watershed study. Located in Mendocino County, the site provides a place for California researchers and decision makers to learn about the cumulative watershed effects of forest management operations on peak flows, sediment production, anadromous fish, macro-invertebrate communities, nutrient cycling and more. Historic data was used to calibrate the Distributed Hydrology Soil Vegetation Model (DHSVM) and River Basin Model (RBM) to measured stream temperatures in the South Fork of Caspar Creek (SFC) for hydrologic years 2010-2016. Critical summer time periods, when temperatures are highest and flows are low, are the primary concern for this work. The key modeling scenarios evaluated were (1) varying percentages of Watercourse and Lake Protection Zones (WLPZ) canopy cover, (2) the 2018-2019 SFC forest harvest and (3) an experimental design converting dominant riparian vegetation along 300-yard stream reaches. Modeling results showed that stream temperatures begin to rise above third-growth conditions when canopy cover is reduced to 25% and 0% retention levels. Larger increases in Maximum Weekly Maximum Temperature (MWMT) values, compared to Maximum Weekly Average Temperature (MWAT) values, were seen across all scenarios. There was essentially no difference between altering buffer areas along only class I streams, compared to along all stream classes. At the 0% canopy retention, MWMT values consistently rose above recommended thermal limits for Coho salmon (Oncorhynchus kisutch) and state regulations prohibiting more than a 5 degree F increase in waters. Clearcutting the entire watershed produced less of an effect than simulations clearing on only the riparian area, suggesting that groundwater inflows act to mitigate stream temperature rises in the SFC. The 2018-2019 harvest showed a relatively consistent increase in MWAT values (avg. 0.11 degree C) and more varied increases in MWMT values (avg. 0.32 degree C). Simulations converting dominant riparian vegetation by clearing could not be considered conclusive due to sensitivity analyses suggesting potentially unrealistic tracking of downstream temperatures. Additional sensitivity analyses suggest that tree height and the monthly extinction coefficient (a function of Leaf Area Index) are most influential on stream temperature changes in SFC. This is consistent with other modeling studies and suggests stream temperature management focus on tall, dense buffers as opposed to wider buffer widths.

The use of fossil derived products and the environmental and economic problems associated with them have made a shift to abundant renewable resources such as forest biomass more attractive. However before forest biomass can be used as a resource, its properties must be known. This study determined the physical properties of heterogeneous biomass residues produced during harvesting on two operational forest sites within the Great Lakes-St Lawrence forest of south-eastern Ontario. Properties measured were moisture content, size distribution, bulk density, and wood-to-bark ratio; also thermo-chemical properties including elemental composition, thermal reactivity and energy content were measured. The effects of forest site and harvest type, storage and position in storage pile, on the properties of biomass were also investigated. Results of the study showed that the various heterogeneous forest harvest residues differed more physically than thermo-chemically for the different variables, and this affected biomass procurement more than the potential utilization options.

This dissertation is an empirical modeling investigation of the impact of forest harvesting, climate change and topography on stream nitrate fluxes in the Turkey Lakes Watershed (TLW), Ontario, Canada. Data used for this study include topography (DEM), climate (mean monthly temperature and total monthly precipitation), wet nitrogen deposition (total monthly nitrate-N and ammonium-N), nitrate water samples and streamflow in 13 headwater catchments within the TLW. First, a paired-watershed approach was used to examine the impact of forest harvesting intensity on stream water nitrate fluxes by developing transfer function noise (TFN) models that related monthly stream water nitrate fluxes of three treatment catchments to those of one control catchment. Second, TFN models were also developed to relate monthly stream nitrate fluxes in 13 catchments to the temperature, precipitation and wet nitrogen deposition to examine the spatially varying responses of stream nitrate fluxes to changes in climate and bulk deposition. Third, geographically weighted regression (GWR) was introduced to model the spatial and temporal relationships between topography and stream nitrate fluxes in 13 headwater catchments. The results showed that there existed a new phenomenon of clustered wave-up and wave-down of the stream nitrate increases caused by clearcut and selectioncut at the monthly scale, respectively. This phenomenon was never reported by previous studies because it was not possible to be identified with ordinary least squares (OLS) regression at an annual scale. There also existed significant responses of stream nitrate fluxes to wet nitrogen deposition in all catchments at the monthly scale over a long-term record between 1982 and 2003. These responses were previously thought to be lower and masked by the impact of climate variations. There further existed significant spatial and seasonal variability of the relationships between topography and stream nitrate fluxes across space and over time. This variability was largely ignored in previous studies with possibly misleading interpretation on the empirical relations. / Thesis (Ph.D, Geography) -- Queen's University, 2012-12-31 22:37:39.137

The impact of natural and anthropogenic disturbances on catchment hydrological and biogeochemical dynamics are difficult or impossible to capture through experimentation or observation alone. Process-based simulation models can address this need by providing a framework for synthesizing data describing catchment responses to climate, harvest, fire, and other disturbances. However, existing models are either too simple to capture important process-level hydrological and biogeochemical controls on ecosystem responses to disturbance, or are too computationally expensive to simulate the local dynamics over large watershed areas, or require a high level of expertise to implement. To this end, a spatially distributed, physically based, eco-hydrological model (VELMA: Visualizing Ecosystems for Land Management Assessments) that is both computationally efficient and relatively easy to implement is developed. VELMA is a state-of-the-art model with real-time visualization tools that shows temporal and spatial patterns of state and flux variables, and is used to address the effects of changes in climate, land-use, and other interacting stressors on multiple ecosystem services such as timber production, carbon sequestration, regulation of water quality and quantity and reduction of greenhouse gases at scales relevant to formulating management decisions. In this study, VELMA was applied to the H.J. Andrews Experimental forest, an intensively studied watershed with observed daily temperature, precipitation, streamflow, and nutrient losses data. VELMA was first used to explore the factors that controls catchment response to forest harvest. Specifically, elucidate how forest harvest factors such as harvest location and amount control watershed hydrological and biogeochemical fluxes. Thereafter, VELMA was used to reconstruct and analyze the impact of two significant disturbance events − a stand replacing fire and a 100% clearcut − on vegetation and soil carbon and nitrogen dynamics. Finally, VELMA was used to explore the potential impact of climate change on catchment hydrological regime, site productivity and carbon and nitrogen dynamics at high spatial resolution relevant to formulating management decision. The main insights from this study include: (1) streamflow, nutrient losses to the stream, and gaseous carbon and nitrogen losses to the atmosphere are strongly sensitive to the location of harvest as a result of the spatial variation in soil water content, plant nitrogen uptake, soil organic carbon decomposition, nitrification, and denitrification within the watershed, (2) forested riparian buffers reduce water and nutrient losses to the stream through plant transpiration, plant nitrogen uptake, soil storage, and soil microbial decomposition, (3) following fire and harvest, losses of N from the terrestrial system to the stream are tightly constrained by the hydrological cycle and driven mainly by wet-season rain events large enough to generate hydrologic connectivity and flushing of nutrients along hillslopes, (4) climate change strongly impacts the hydrological regime in the Pacific Northwest as a result of less snowpack, earlier snowmelt, higher winter streamflow, lower summer streamflow, and soil moisture deficit, and (5) climate change increases plant and soil biomass accumulation as a result of longer growing season and higher soil organic decomposition, reduce water quality by increasing the amount of nutrients that reach the stream, and transforms the ecosystem into a net source of carbon to the atmosphere.

The use of fossil derived products and the environmental and economic problems associated with them have made a shift to abundant renewable resources such as forest biomass more attractive. However before forest biomass can be used as a resource, its properties must be known. This study determined the physical properties of heterogeneous biomass residues produced during harvesting on two operational forest sites within the Great Lakes-St Lawrence forest of south-eastern Ontario. Properties measured were moisture content, size distribution, bulk density, and wood-to-bark ratio; also thermo-chemical properties including elemental composition, thermal reactivity and energy content were measured. The effects of forest site and harvest type, storage and position in storage pile, on the properties of biomass were also investigated. Results of the study showed that the various heterogeneous forest harvest residues differed more physically than thermo-chemically for the different variables, and this affected biomass procurement more than the potential utilization options.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2017-12-11T15:50:46Z No. of bitstreams: 1 PGEF17MA072.pdf: 1540009 bytes, checksum: 0a6a0c91bcb17bc18be105a058020b75 (MD5) / Made available in DSpace on 2017-12-11T15:50:46Z (GMT). No. of bitstreams: 1 PGEF17MA072.pdf: 1540009 bytes, checksum: 0a6a0c91bcb17bc18be105a058020b75 (MD5) Previous issue date: 2017-02-20 / Some organizations in the Brazilian forestry industry do not follow the development pace of other industries, or the adoption rate of management and quality methodologies and tools. As result, the low quality and high instability of processes create a lot of waste in the sector. This is intensified when it happens during the harvesting, one of the activities that most contributes to the production costs of a forestry business. This study aimed to evaluate the predictability of timber harvesting process based on critical points identified in the thinning and harvest operations. For this, research was divided in three stages. The first one was mapping the harvesting process and the elaboration of fluxograms. The second stage was the identification, through interviews, and assessment of critical points using the Failure Mode and Effect Analysis (FMEA) and Pareto chart. The third stage was the evaluation of the process using Statistical Process Control (SPC) through attributes and variable in the main failures. In the interviews conducted with workers, seven critical points were identified: damage to the remaining trees, sorting, stump height, dirt in load, knot on the second log, tree left in the field and safety. The evaluation with Pareto chart showed that 80% of the failures identified during harvest are attributed to three causes: damage to the remaining trees, sorting and stump height. The FMEA analysis showed that the failure with highest risk index was knots on the second log, followed by safety. For evaluation with the SPC, damage to remaining trees, sorting and stump height were selected. In general, control charts showed that the forest harvest process was considered unstable and unpredictable, even though it is within the limits defined by the company / No setor florestal brasileiro, algumas organizações não acompanham o ritmo do desenvolvimento de outros setores e da adoção de ferramentas e metodologias de gestão da qualidade. Em função deste atraso, a baixa qualidade e alta instabilidade dos processos, geram grandes desperdícios nas organizações. O fato se agrava quando ocorre na operação de colheita da madeira, uma das atividades que mais contribui nos custos de produção da empresa florestal. Este trabalho objetivou avaliar o processo de colheita florestal de uma empresa quanto a sua previsibilidade com base nos pontos críticos identificados nas operações de desbaste e corte raso. Para isso, a pesquisa foi dividida em três etapas, a primeira foi o mapeamento do processo de colheita e elaboração de fluxogramas. A segunda etapa foi a identificação, por meio de entrevistas, e avaliação dos pontos críticos utilizando a metodologia Failure Mode and Effect Analysis – FMEA e gráfico de Pareto. A terceira fase foi a avaliação do processo empregando o Controle Estatístico do Processo (CEP) por atributos e variáveis nas principais falhas. Nas entrevistas realizadas com os colaboradores, sete pontos críticos foram apontados: danos às árvores remanescentes, sortimento, altura de toco, sujeira na carga, nó na 2ª tora, árvores deixadas no talhão e segurança. Na avaliação com o gráfico de Pareto, observou-se que cerca de 80% dos problemas identificados na colheita da empresa são atribuídos às três primeiras causas supracitadas. A análise com o FMEA indicou que a falha com maior índice de risco foi o nó na 2ª tora, seguido da segurança. Para a avaliação com o CEP, selecionou-se os pontos críticos: danos às árvores remanescentes, sortimento e altura de toco. De maneira geral, os gráficos de controle indicaram que o processo da colheita florestal, apesar de estar dentro dos limites especificados pela empresa, foi considerado instável e não previsível

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