Portland State University. Department of Geography
Jiunn-Der (Geoffrey) Duh
Date of Award
Master of Science (M.S.) in Geography
Western juniper -- Ecology -- Oregon, Steppe restoration -- Oregon, Steppe ecology -- Oregon
Western juniper (Juniperus occidentalis var. occidentalis) has been expanding its biogeographic range since the mid-1800's, resulting in decreased biodiversity, altered wildlife habitat, increased soil erosion, reduced stream flows and reduced forage production. The direct causes of western juniper aforestation are unclear but appear to be related to altered fire regimes, over grazing, and climatic shifts.
This study seeks to determine how Landsat images combined with Digital Orthoquads (DOQs) can be used to examine the geographic distribution of western juniper. Satellite imagery has yet to be applied to the large scale mapping of western juniper aforestation, resulting in the lack of regional and landscape level monitoring of western juniper range expansion. Remote sensing technologies, when combined with geographical information systems provide potentially valuable tools for monitoring western juniper expansion because of their abilities to assess large scale coverage of scenes, high cost effectiveness, and minimal field crew requirements. The two main objectives of my research are to review and summarize current literature regarding western juniper expansion and explore how remote sensing techniques may be used to quantify the expansion of the species. The results of my studies suggest that large patches of western juniper are detectable using Landsat imagery.
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Goralski, Elizabeth A., "Western Juniper (Juniperus occidentalis) Ecology with an Exercise in Remote Sensing Techniques" (2008). Geography Masters Research Papers. 11.