Vegetation changes in the Delta Marsh, Manitoba between 1948-80 / Petronella Maria Johanna de Geus.
Material type: TextPublication details: Winnipeg, MB : University of Manitoba, 1987.Description: viii, 97 leaves : ill. ; 28 cmOnline resources: Abstract: Historically, under the influence of climatic cycles, water levels in Lake Manitoba and the adjacent Delta Marsh fluctuated with a range of more than 2.2 m. In 1961, a regulation regime was imposed on the lake and water level fluctuations have been dampened to less than 0.6 m.Aerial photographs taken in 1948 (low water) and 1954 (high water) were used to determine changes in the distribution of three dominants Typha species, Phragmites australis and Scolochloa festucacea, and water and mudflats along elevational gradients in response to fluctuating water levels. Post- regulation changes were determined from aerial photographs taken in 1964, 1972 and 1980. Pre-regulation marsh shorelines were dominated by Phragmites. After regulation was imposed there was a change to a Typha dominated marsh. Typha, probably the hybrid T. glauca,expanded its range up the elevation gradient by encroaching upon Phragmites and down the gradient by invading shallow water. Lattice profile analysis providedItem type | Current library | Collection | Call number | Status | Date due | Barcode |
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Electronic Report | Electronic Library | Non-fiction | DEG (Browse shelf(Opens below)) | Available | 1462 |
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Thesis(M.Sc.)--University of Manitoba, 1987.
Includes bibliographical references (leaves 78-82).
Historically, under the influence of climatic cycles, water levels in Lake Manitoba and the adjacent Delta Marsh fluctuated with a range of more than 2.2 m. In 1961, a regulation regime was imposed on the lake and water level fluctuations have been dampened to less than 0.6 m.Aerial photographs taken in 1948 (low water) and 1954 (high water) were used to determine changes in the distribution of three dominants Typha species, Phragmites australis and Scolochloa festucacea, and water and mudflats along elevational gradients in response to fluctuating water levels. Post- regulation changes were determined from aerial photographs taken in 1964, 1972 and 1980. Pre-regulation marsh shorelines were dominated by Phragmites. After regulation was imposed there was a change to a Typha dominated marsh. Typha, probably the hybrid T. glauca,expanded its range up the elevation gradient by encroaching upon Phragmites and down the gradient by invading shallow water. Lattice profile analysis provided