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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.
1

Spring and Summer Habitat Preferences of Blue Grouse on the Bear River Range, Utah

Maestro, Robert M. 01 May 1971 (has links)
A study of the spring and summer habitat preferences of blue grouse was conducted on the Bear River Range in northern Utah. The main objective was to determine the important factors associated with habitat selection by blue grouse during the breeding season. One hundred and two sampling areas, delimited by similarities in vegetation and topography, were thoroughly searched with a dog for blue grouse. Fifty-four bio logical and physical variables were measured for each sampling area. Chi-square tests performed on all variables showed 11 of the 54 variables to be significant at an alpha of 0.20. These 11 variables (li sted below) were considered to be the important factors influencing habitat selection by blue grouse. (1) search area type (2) area exposure (3) elevation (4) percent forested (5) understory density (6) primary cover species (7) secondary cover species (8) percent cover maples (Acer grandidentatum) (9) percent cover mixed brush (10) percent cover sagebrush (Artemisia tridentata) (11) total acres The chi-square test only determined if a variable significantly effected habitat selection by blue grouse. To determine whether this effect was positive or negative, the percent occurrence of areas on which blue grouse were present, or absent, was determined. Results indicated that the most favorable blue grouse habitat was draws at 5,500 -6.499 feet elevation. This favorable habitat contained 1-10 percent cover by maples, or a higher percent of maple which provided a large amount of edge effect; the presence of mixed brush or sagebrush, a medium understory, and an area incline of 5-19 percent.
2

An Examination of Sea Ice Spring and Summer Retreat in the Canadian Arctic Archipelago: 1989 to 2010

Tan, Wenxia 21 August 2013 (has links)
The sea ice extent change and variability of the Canadian Arctic Archipelago (CAA) are quite different compared to the Arctic as a whole due to its unique geographic settings. In this thesis, the sea ice retreat processes, the connection with other Arctic regions, and the linkages to the surface radiation flux in the CAA are examined. The sea ice retreat processes in the CAA follow a four-phase process: a slow ice melt phase that usually lasts until early June (phase 1); a quick melt phase with large daily sea ice extent change which lasts close to half-a-month (phase 2); a slow melt phase that looks like slow sea ice melt or even a small ice increase that lasts another half-a-month (phase 3); and a steady ice decrease phase (phase 4). With the help of Moderate-Resolution Imaging Spectroradiometer (MODIS) data, it is identified that the quick melt in phase 2 is actually melt ponding, with melt ponds being falsely identified as open water by passive microwave. A simplified data assimilation method is then developed to improve the passive microwave sea ice concentration estimation by fusion with MODIS ice surface temperature data. The ice concentration from the analysis is found to improve the original passive microwave sea ice concentration estimation, with the largest improvements during sea ice melt. The sea ice retreat patterns in the CAA region are correlated with the sea ice retreat patterns in other regions of the Arctic. A decision tree classifier is designed to segment the sea ice retreat patterns in the CAA into several classes and classification maps are generated. These maps are effective in identifying the geographic locations that have large changes in the sea ice retreat patterns through the years. The daily progressions of the surface radiation components are described in detail. Due to the lack of multiple reflection, the percentage of shortwave radiation at the top of atmosphere that reaches the surface is influenced by the form of melt ponds over ice surface. The roles that each surface radiation component plays in forcing sea ice retreat are different in different years.

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