To further the understanding of respiration processes of northern peatlands, the relative importance of each type of belowground respiration was determined at Mer Bleue, a northern peatland located near Ottawa, Ontario, from June to November, 2003. Direct measurements of total, soil organic matter (SOM) and root respiration were made, with rhizosphere respiration determined by residual. Although an aboveground source, determination of live Sphagnum respiration was also attempted in the field. To identify changes in CO2 fluxes with environmental conditions, peat temperature and water table levels were monitored throughout the study period. / SOM respiration was higher than hypothesized at 63% while root and rhizosphere respiration were lower than hypothesized at 21% and 16%, respectively, of total belowground respiration. As the field experiment for determining live Sphagnum respiration was unsuccessful, it was determined by calculation to be 18% of total respiration, slightly higher than hypothesized. Opposite of hypothesized, air temperatures, peat temperatures and water table levels generally had weak and insignificant relationships when linearly regressed with total respiration.

To examine bat - habitat relationships, ultrasonic detectors were used to sample bat activity among: old-growth white pine (Pinus strobus ), mature white pine, boreal mixedwood, and selectively-cut white pine stands in central Ontario. Within the stands, bats were sampled in the canopy, the understory layer, and within canopy gaps. Forest structure was measured within each of the stands. The activity of bats was compared among forest stand types, within the stands, and in relation to forest structure. Also, maintaining forest wildlife populations requires data on the use of snags (i.e. dead trees). To provide further resolution of the habitat requirements of forest-dwelling bats, radio telemetry and exit counts were used to investigate the roosting ecology of mouse-eared bats (Myotis lucifugus and M. septentrionalis). Characteristics of snags used by mouse-eared bats were compared with randomly located snags and random geographic points, at three spatial scales (focal tree, surrounding forest, and landscape). (Abstract shortened by UMI.)

Black spruce (Picea mariana (Mill.) B.S.P.)-feathermoss forests are a common subtype of the northern boreal forests. These forests are associated with large accumulations of mor humus, which is regarded as an important source of nutrients, contributor to soil structure, moisture retention and vital to the long-term sustainability of these forests. Harvesting with protection of advance regeneration (CPRS) is currently used in northwestern Quebec as the method for sustainable management, which reduces soil compaction and protects advance regeneration, and genetic diversity. We examined the effects of CPRS on organic matter and advance regeneration 6 years after harvesting. During the summer of 2002, a humus classification based on observable field characteristics was developed and applied to six CPRS sites in the northern Abitibi claybelt region of Quebec. At each site 75 humus profiles were surveyed and classified by order and thickness of horizons present. Humus horizons were easily observed using morphological features, and master horizon classes were distinguished by their nutritional and biochemical attributes with differences occurring as a result of the natural process of decomposition. Individual humus horizon and total profile thickness was the variable that most affected profile nutrient mass. High forest floor disturbance was associated with shallow profile depth, resulting in low humus profile nutrient mass and low density advance regeneration. Lower forest floor disturbance resulted in deeper profiles associated with higher available nutrients in humus profiles and higher density of advance regeneration. These results suggest that disturbance caused by harvesting may reduce overall stand productivity in the short term due to the effect of low tree density and possibly in the long-term due to loss of nutrients.

Net ecosystem exchange of CO$ sb2$ (NEE) and CH$ sb4$ flux were measured at five sites within a boreal peatland near Thompson, Manitoba, from June through September, 1994. Sites were chosen to represent the different plant communities present along a productivity gradient where the water table was at or near the peat surface. Methane emissions, water table depth, and peat temperature were measured on weekly basis, while the relationship between photosynthetically active radiation (PAR) and net ecosystem exchange of CO$ sb2$ was determined three times during the field season, and then used to develop net ecosystem production (NEP) models at each site. Porewater methane was sampled for $ rm delta sp{13}C/ sp{12}C$ isotopic analysis once a month. / Among the sites, after PAR, light CO$ sb2$ flux was primarily controlled by sedge biomass and water table position, while dark CO$ sb2$ flux was controlled by peat temperature. From early June to late August, the five sites consumed approximately 1 to 2 g $ rm CO sb2$-C m$ rm sp{-2}d sp{-1}$. Seasonal CH$ sb4$ fluxes ranged between 16 and 456 mg $ rm CH sb4 m sp{-2}d sp{-1}$, and were higher than fluxes measured at other boreal sites in the same latitude. Seasonal average NEP was a good predictor of seasonal CH$ sb4$ fluxes from the sites (r$ sp2$ = 0.50), providing a model which estimates CH$ sb4$ flux based on site productivity alone. Stable carbon isotope analysis indicates root exudates that stimulate methanogenesis are an important control on this relationship, as is a high water table, particularly in its influence on the depth of the CH$ sb4$ oxidizing layer in the peat. These results suggest NEP measurements have the potential to be used in remote sensing applications to estimate CH$ sb4$ flux from wetlands, but that their use may be restricted to inundated sites.

The coastal fish community of Wemindji, eastern James Bay, was studied to describe seasonal utilization of the Maquatua River estuary and the adjacent coastal waters by marine and anadromous fishes. During summer, the estuarine fishes are numerically dominated by the fourhorn sculpin (Myoxocephalus quadricornis) and the slender eelblenny (Lumpenus fabricii), and also by juvenile cisco (Coregonus artedii) and whitefish (C. clupeaformis). In coastal waters, three marine species are abundant: the shorthorn sculpin (M. scorpius), the arctic sculpin (M. scorpioides) and the Greenland cod (Gadus ogac). / Greenland cod were studied in the same period. During the summer, they principally occupied shallow coastal waters, characterized by a belt of eelgrass (Zostera marina). In winter, more cod were found in the estuary. This movement corresponds to sexual maturity; spawning occurs in April to June. Greenland cod life history variables differ from those of most arctic benthic fishes: they show rapid growth, high fecundity, low age at first maturity and high mortality.

Based on the author's dissertation-- Eberhard-Karls-Universität, Tübingen, 2001. / 1 folded map in pocket. Includes bibliographical references and indexes.

Thèse no 1788 sc. techn. EPF Lausanne. / Bibliogr.

Zugl.: Leipzig, Univ., Diss., 2009

Zugl.: Leipzig, Univ., Diss., 2009

Osnabrück, Univ., Diss., 2000. / Computerdatei im Fernzugriff.