In order to determine the impact of lesser snow goose (Chen caerulescens caerulescens) herbivory on above and belowground nutrient dynamics, a grazing and nutrient addition experiment was conducted in two habitat types utilized by snow geese near Churchill, Manitoba. Forage plant nutrition, soil microbial biomass, and inorganic and organic soil nutrients were measured in relation to the timing of grazing, over two consecutive summers. Soil was collected from the rhizosphere to determine the influence of foliar herbivory on root-microbe interactions. Primary productivity in both habitats is co-limited by the availability of both nitrogen (N) and phosphorus (P). Aboveground defoliation either caused a reduction or no change in soil microbial biomass nutrients (carbon (C), N, or P). Defoliated shoots had higher N concentrations and did not show compensatory growth within the season. Root biomass was somewhat reduced with grazing, but higher whole plant N content suggests that grazing does not compromise N-uptake.

In order to determine the impact of lesser snow goose (Chen caerulescens caerulescens) herbivory on above and belowground nutrient dynamics, a grazing and nutrient addition experiment was conducted in two habitat types utilized by snow geese near Churchill, Manitoba. Forage plant nutrition, soil microbial biomass, and inorganic and organic soil nutrients were measured in relation to the timing of grazing, over two consecutive summers. Soil was collected from the rhizosphere to determine the influence of foliar herbivory on root-microbe interactions. Primary productivity in both habitats is co-limited by the availability of both nitrogen (N) and phosphorus (P). Aboveground defoliation either caused a reduction or no change in soil microbial biomass nutrients (carbon (C), N, or P). Defoliated shoots had higher N concentrations and did not show compensatory growth within the season. Root biomass was somewhat reduced with grazing, but higher whole plant N content suggests that grazing does not compromise N-uptake.

Snowfall interception is particularly important to the hydrology of forested cold regions. Unloading of intercepted snow controls the snow available for interception loss due to sublimation from that held in the canopy. This thesis seeks to determine the factors that affect the magnitude and timing of unloading at the forest-stand scale. A field program was established that measured interception and unloading at a forest-stand scale using a series of hanging lysimeters and a 7 m tall spruce tree suspended, in-situ, on a load-cell.<p> Meteorological conditions including snowfall, wind speed, air temperature, and incoming radiation were recorded above and below the forest canopy. Unloading did not behave as described by current unloading models. It was observed to be triggered by occurrences of wind gusts or melt conditions within the canopy but no trends were found in the measurements that could be used to predict the onset of unloading from gusts or air temperature alone. An association between intercepted snow sublimation and unloading was found and this relationship was further found to be an exponential function of air temperature. An expression based on this empirical model can be used to calculate unloading as a function of sublimation rate in hydrological models or to calculate unloading directly as a function of canopy snow load and air temperature.

A fully automatic de-weathering system to increase the visibility/stability in surveillance applications during bad weather has been developed. Rain, snow and haze during daylight are handled in real-time performance with acceleration from CUDA implemented algorithms. Video from fixed cameras is processed on a PC with no need of special hardware except an NVidia GPU. The system does not use any background model and does not require any precalibration. Increase in contrast is obtained in all haze/rain/snow-cases while the system lags the maximum of one frame during rain or snow removal. De-hazing can be obtained for any distance to simplify tracking or other operating algorithms on a surveillance system.

Snow Albedo Feedback (SAF) in response to climate change is a process that can amplify the climate warming response to increases in anthropogenic atmospheric CO2 concentrations from the 20th to the 21st Century. Warmer surface air temperature may induce snowmelt and expose darker underlying surfaces which absorb more incoming solar radiation and further increase the ambient temperature. Springtime SAF in the fully Coupled Model Intercomparison Project Phase 3 (CMIP3) models is associated with summertime circulation. However, no clear physical mechanism explaining this link has been found. Furthermore, there is a large intermodel spread in the projection of SAF among the CMIP3 models which is primarily controlled through the parameterization of snow albedo in each model. Limited work was conducted on assessing the response of SAF to that of an isolated controlling parameter such as snow albedo. Here, the uncoupled Geophysical Fluid Dynamics Laboratory Atmospheric Model 2.1 (AM2.1) was used to diagnose SAF in the CMIP3 models by conducting a set of sensitivity experiments with perturbed snow albedo. This was performed to remove indirect external climate factors that may influence SAF and to use the simplified uncoupled model to understand the behaviours exhibited by the complex coupled models. Snow cover extent (SNC) and snow metamorphosis as a function of temperature (TEM) that influences SAF, as well as the knock-on effects of SAF on soil moisture, snow mass, snow melt and circulation were analyzed using both the CMIP3 and AM2.1 models. In addition, it was hypothesized that summertime Land Sea Contrast response to climate change (dLSC) is a physical mechanism that induces summertime circulation patterns in relation to springtime SAF. It is found that the AM2.1 can similarly reproduce SNC and TEM as well as the spread in SAF exhibited in the CMIP3 models. However, no robust link can be determined between SAF and its knock-on effects. Furthermore, the correlation between SAF and dLSC is not significant and thus dLSC is not a physical mechanism that influences the summertime circulation patterns in response to climate change. It is the expectation that these research results can provide an in-depth understanding of the role of SAF among fully coupled GCMs through tests performed by the uncoupled simulation.

Snowfall interception is particularly important to the hydrology of forested cold regions. Unloading of intercepted snow controls the snow available for interception loss due to sublimation from that held in the canopy. This thesis seeks to determine the factors that affect the magnitude and timing of unloading at the forest-stand scale. A field program was established that measured interception and unloading at a forest-stand scale using a series of hanging lysimeters and a 7 m tall spruce tree suspended, in-situ, on a load-cell.<p> Meteorological conditions including snowfall, wind speed, air temperature, and incoming radiation were recorded above and below the forest canopy. Unloading did not behave as described by current unloading models. It was observed to be triggered by occurrences of wind gusts or melt conditions within the canopy but no trends were found in the measurements that could be used to predict the onset of unloading from gusts or air temperature alone. An association between intercepted snow sublimation and unloading was found and this relationship was further found to be an exponential function of air temperature. An expression based on this empirical model can be used to calculate unloading as a function of sublimation rate in hydrological models or to calculate unloading directly as a function of canopy snow load and air temperature.

Univ., Diss.--Bremen, 2006. / Enth. außerdem 3 Papers.

No description available.

No description available.

In June 2005, fieldwork was conducted during the spring snowmelt period at Cape Bounty, Melville Island, Nunavut to examine the relationships between snow accumulation, runoff, and nutrient fluxes in two High Arctic watersheds. The snowcover was quantified by means of eleven depth and three density measurements at 42 survey transects (100 m) distributed throughout the West and East watersheds. River discharge was monitored at the watershed outlets, where water samples were collected four times daily during the first ten days of melt and twice daily once flow receded. Water samples were also collected from headwater and tributary sites in the two watersheds, and samples were analyzed for DOC, DON and DIN (NH4+ and NO3-). An objective terrain classification weighted equally on slope, aspect and land surface curvature was applied to the two watersheds using an ISODATA unsupervised classification scheme to determine watershed SWE. The terrain model confirmed that topography likely explains greater SWE in the West watershed, and provides a method for reproducible estimates of watershed SWE in future years. However, improved methods for estimating SWE in channels and deep snowbanks are required to ensure accurate assessments of watershed SWE. The seasonal trends in DOC, DON, and DIN concentrations and specific fluxes are reported for both watersheds. The export of DON and DIN was strongly correlated with DOC in the West watershed, indicating that the flushing of terrestrial nutrients from surficial soils by snowmelt runoff governs nutrient export. Despite less watershed SWE (51%), the East watershed exported greater specific fluxes of DOC (33%) and DON (43%) during the melt season. This suggests that the East watershed had greater connectivity with OM sources early in the melt season. Furthermore, low DOC:DON ratios (< 15) in the East River indicate that a larger portion of DOM was likely derived from algal or microbial sources in the East watershed relative to the West watershed. The export of DIN was similar in the two watersheds, and results suggest that DIN export was likely controlled by watershed vegetation coverage and runoff volumes during snowmelt. / Thesis (Master, Geography) -- Queen's University, 2008-07-08 00:31:46.107