The plate-boundary Alpine Fault runs immediately offshore of the popular tourist destination of Milford Sound, which is visited by more than half a million tourists each year. Glaciers retreated from the fiord between ~24-16 ka, leaving behind a legacy of extreme topography, including some of the world's highest sea cliffs, which tower nearly 2 km above the fiord. Visitors come to view the spectacularly steep and rugged landscape, with many cruising the fiord by boat. This project utilizes surface exposure dating (TCND) of glacially modified surfaces, to gain further insight into the glacier retreat history of Milford Sound. Exposure dates from strategic locations near the entrance to the fiord indicate that the main trunk glacier had retreated about 9 km from its peak LGM position by ~18 ka. Additional TCND and calibrated Schmidt Hammer data from a range of positions within the Milford catchment provide strong evidence that the main trunk glacier receded rapidly after about 18 ka, retreating a further 16 km to a position near the present-day confluence of the Tutoko and Cleddau rivers, by ~16 ka. Available seismic reflection data suggest that post-glacial sediment infill has been strongly influenced by massive deposits of rock avalanche debris. New high-resolution bathymetric and seismic reflection data reveals the presence of at least 18 very large post-glacial rock avalanche deposits which blanket ~40% of the fiord bottom. Geomorphic mapping and field investigation reveal the presence of at least ten additional very large to giant terrestrial landslide deposits in the lower Milford catchment; radiocarbon and surface exposure dating indicate that these events occurred during the Holocene, between ~9-1 ka. Ages of six of these deposits are in agreement with published rupture dates on the southern on-shore portion of the Alpine Fault.

The short-term responses of Cassiope tetragona, a high arctic evergreen shrub, to variations in growing season climate were examined using experimental manipulations of temperature and growing season length at Alexandra Fiord, Ellesmere Island. Surface temperatures in the field were increased an average of 1-2 °C in two communities using open-top greenhouses. Growing season length was altered in a snowbed community by using manual snow manipulations to change the date of snowmelt. Growth and reproductive responses of Cassiope tetragona to these manipulations were observed over two field seasons following treatment establishment. Natural variations in vegetative and reproductive characteristics of Cassiope tetragona were also monitored in unmanipulated communities selected to represent a range of environmental conditions at the study site. Retrospective analysis of past Cassiope growth and reproduction was used to provide a record of variations in productivity spanning 25-35 years which could be related to climate records from Ellesmere Island. For the retrospective analysis, patterns of internode lengths were used to delimit sections of annual growth and chronologies of annual stem elongation, leaf number and flower number were then analyzed using methods similar to those applied to tree-ring studies. In general, the reproductive parameters of Cassiope tetragona were observed to be highly responsive to short-term variations in growing season climate, while vegetative production exhibited a much more conservative response. Flower production and rates of reproductive development were significantly stimulated by experimental warming. Retrospective analysis of flower production support field observations indicating that flower production is highly sensitive to annual variations in growing season temperatures. In contrast, shoot growth showed moderate responses to experimental warming. Records of past growth indicate that although vegetative production appears to be sensitive to annual variations in summer temperatures, the degree of responsiveness is much lower than for reproductive parameters. Net growth and reproduction were not stronly affected by natural or experimental variations in snowmelt timing, although phenology timing was significantly altered. The conservative growth response of Cassiope tetragona to short-term variations in climate is suggested to be related to constraints on plant phenology which may restrict flexibility in the period utilized by plants for aboveground growth. Preferential allocation of within-plant resources to reproductive structures during periods of ameliorated growing season climate may account for the observed strong reproductive responses to climate variations. Trade-offs betweeen growth and reproduction have important implications for predicting the long-term response of Cassiope tetragona to climate change. An understanding of within-plant allocation strategies is also important to the interpretation of past variations in growth and reproduction. Retrospective analysis of past Cassiope production is likely to be a very useful tool for investigating ecological relationships and past climate change.

The short-term responses of Cassiope tetragona, a high arctic evergreen shrub, to variations in growing season climate were examined using experimental manipulations of temperature and growing season length at Alexandra Fiord, Ellesmere Island. Surface temperatures in the field were increased an average of 1-2 °C in two communities using open-top greenhouses. Growing season length was altered in a snowbed community by using manual snow manipulations to change the date of snowmelt. Growth and reproductive responses of Cassiope tetragona to these manipulations were observed over two field seasons following treatment establishment. Natural variations in vegetative and reproductive characteristics of Cassiope tetragona were also monitored in unmanipulated communities selected to represent a range of environmental conditions at the study site. Retrospective analysis of past Cassiope growth and reproduction was used to provide a record of variations in productivity spanning 25-35 years which could be related to climate records from Ellesmere Island. For the retrospective analysis, patterns of internode lengths were used to delimit sections of annual growth and chronologies of annual stem elongation, leaf number and flower number were then analyzed using methods similar to those applied to tree-ring studies. In general, the reproductive parameters of Cassiope tetragona were observed to be highly responsive to short-term variations in growing season climate, while vegetative production exhibited a much more conservative response. Flower production and rates of reproductive development were significantly stimulated by experimental warming. Retrospective analysis of flower production support field observations indicating that flower production is highly sensitive to annual variations in growing season temperatures. In contrast, shoot growth showed moderate responses to experimental warming. Records of past growth indicate that although vegetative production appears to be sensitive to annual variations in summer temperatures, the degree of responsiveness is much lower than for reproductive parameters. Net growth and reproduction were not stronly affected by natural or experimental variations in snowmelt timing, although phenology timing was significantly altered. The conservative growth response of Cassiope tetragona to short-term variations in climate is suggested to be related to constraints on plant phenology which may restrict flexibility in the period utilized by plants for aboveground growth. Preferential allocation of within-plant resources to reproductive structures during periods of ameliorated growing season climate may account for the observed strong reproductive responses to climate variations. Trade-offs betweeen growth and reproduction have important implications for predicting the long-term response of Cassiope tetragona to climate change. An understanding of within-plant allocation strategies is also important to the interpretation of past variations in growth and reproduction. Retrospective analysis of past Cassiope production is likely to be a very useful tool for investigating ecological relationships and past climate change. / Arts, Faculty of / Geography, Department of / Graduate