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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Taking a good long look : disturbance, succession, landscape change and repeat photography in the upper Blakiston Valley, Waterton Lakes National Park

Watt-Gremm, Graham Duff 06 April 2010 (has links)
Understanding historical disturbance and succession is critical in park management and restoration. I examined successional patterns and disturbance dynamics in the Blakiston Valley, Waterton Lakes National Park, by analyzing changes in forest structure using field research and repeat photography. I sampled forest structural attributes in 23 stands and interpreted forest cover from oblique and aerial photographs from 1881, 1914, 1947 and 2004. I quantitatively compared the interpretation from oblique photographs to aerial photographs and geographic information system (GIS) data and related succession to environmental factors and historical disturbances. Successional patterns were dominated by transitions from open meadows and shrublands to woodlands and closed forests, and were related to a small number of environment and disturbance variables, especially elevation, potential radiation, and time since last recorded fire. Accompanying these trends is a decline in landscape diversity. These findings have implications for restoration and conservation of subalpine forests in the park and across the region. The GIS methods capture spatially approximate vegetation patterns from oblique photographs and show potential for further research, especially in combination with the photograph collection of the Mountain Legacy Project.
22

Forest attributes from multi-angle multi-date remotely sensed data

Dyk, Andrew 30 August 2010 (has links)
Multi-Angle, Multi-Date, Hyperspectral imagery of forests have been used to provide accurate estimates of the canopy characteristics. This thesis investigated the influence of various forest attributes on the spectral reflectance over time and view direction. The Compact High Resolution Imaging Spectrometer (CHRIS) is aboard the ESA PROBA satellite. The revisits of the CHRIS multi-angle images have been used to improve the accuracies of forest species recognition and stand densities compared to a nadir view only. Multi-angle data for CHRIS analysis of forest species produced higher accuracy and were easier to obtain than multi-date date. 5-Scale, a radiative transfer model, and CHRIS data have been compared as inputs into Partial Least Squares (PLS), a fullspectrum analytical method that offers relations between forest stand parameters and the resulting spectra. The resulting coefficients highlight where (view angle and spectral regions) within the multi-angle spectra contributed to estimating the various forest parameters. Methodology of collecting spectral calibration data in the field and the unique pre-processing challenges have been described.
23

Multicentury history of western spruce budworm outbreaks in interior Douglas-fir forests near Kamloops, British Columbia

Campbell, Rochelle. 14 August 2008 (has links)
Western spruce budworm (Choristoneura occidentalis (Freeman)) is a native defoliator of the Interior Douglas-fir (Pseudotsuga menziesii var. glauca (Mirb.) Franco) forests of British Columbia, Canada. This thesis used dendrochronology and the software program OUTBREAK to reconstruct a defoliation history of Douglas-fir for nineteen forest sites near Kamloops in central British Columbia. By comparing the radial growth response of non-host ponderosa pine trees to Douglas-fir trees growing in nearby but separate stands, seven western spruce budworm outbreaks were distinguished over the past 300 years. Although there is considerable variation in the timing and duration of these western spruce budworm events at the stand level, synchronous outbreaks have occurred at approximately 43-year intervals. Climate variation appears to have been important to budworm outbreaks in the 20th century. Notable outbreaks tended to occur during years of early springs with average air temperature, following winters with lower than average precipitation. Based on this finding, it is proposed that with high overwintering survival, increased population growth rates, and a longer growing season, the extent of future outbreaks will shift northward and may increase in size.
24

Production and quality of sap from bigleaf maple (Acer macrophyllum Marsh) on Vancouver Island, British Columbia

Bruce, Deirdre 01 May 2008 (has links)
Bigleaf maple tapping has become increasingly popular on Vancouver Island and additional information is needed to assist in the sustainable development of this non-timber forest product. This research is an exploratory study that investigates sap flow in the 2006/2007 season on Vancouver Island, British Columbia. Sap flow was highly variable throughout the season. Fluctuations in air temperature, above and below zero, were shown to trigger sap flow. This study characterizes the dissolved solid components of the sap and syrup collected during the 2006/2007 season. The carbohydrate content of the bigleaf maple sap is mainly sucrose with a minor component of fructose and glucose. The concentration of carbohydrates varied throughout the season. The main cations in the bigleaf maple sap and syrup are calcium, potassium and magnesium.

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