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Interpretation of large-scale color infrared and color aerial photography can be a labor and cost-effective means for inventorying and monitoring rangelands while maintaining accuracy. Ground measurements of vegetation cover at Organ Pipe Cactus National Monument were taken in 1975 and 1984. Large-scale (1:1200) color and color infrared aerial photo estimates were compared to these ground measurements through regression and correlation to check photo accuracy. Relationships between photo estimates and ground measurements of total vegetation and shrub cover were strong when using either film type. Color infrared photo estimates corresponded better with ground measurements for both tree cover and cactus cover than color photo estimates. Large-scale aerial photography is also useful for determining some of the causes of vegetation change. Evidence gathered from both sets of photos suggested that vegetation change at OPCNM was largely the result of domestic livestock removal and short-term climatic fluctuations.

Phymatotrichum root rot is a fungal disease with a host range that includes many economically important crops in the southwestern United States and Mexico. While it has been studied since the late nineteenth century, ecological relationships of the disease, particularly those related to its distribution and dispersal, are not understood. Combined ground radiance sampling and aerial photographic interpretation was employed to study the distribution of Phymatotrichum root rot in cotton. Radiometric ground sampling showed that diseased cotton has a characteristic spectral signature that is significantly different from healthy cotton at visible wavelengths. Micro-scale examination of distribution within fields utilized multitemporal photography, both within season (1983) and for four seasons (1979-1982), revealed that the disease spreads during a season, but is not recurrent in many cases between years. Meso-scale mapping employed multitemporal photography to map distribution during a four-year period. When compared to mapped soil units, these data revealed a significantly non-random relationship between the diseased areas of fields and fine-textured soil units that may be based on moisture-holding potential. A yield analysis was also preformed using Thematic Mapper Simulator data and computer analysis.

Thesis (M.Sc.)--University of Manitoba, 2006. / A thesis submitted to the Faculty of Graduate Studies in partial fulfillment of the requirements for the degree of Master of Science, Department of Soil Science. Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Plant and Soil Sciences. / Title from title screen. Includes bibliographical references.