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Evaluation of 35mm vertical aerial photography for estimating tree mortality Public Deposited
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Evaluation of four 35 mm film:lens combinations for estimating conifer mortality showed that large-scale true color images obtained with Kodak High Speed Ektachrome and color infrared images obtained with Kodak Ektachrome Infrared, both exposed through a 135 mm lens were best. Higher correlation coefficients were found for the true color:135 combination than color IR:135 combination. Correlation between ground counts and photo counts of stereoscopically examined Kodacolor prints was no better and possibly not as good as correlations between ground counts and enlarged images of projected 35 mm transparencies. * This type and format of photography, as with other types and formats, has its advantages and disadvantages, and would be useful in determining 41 mortality rates or making mortality counts on areas where full coverage is not desired. Other innovations are discussed. Survey designs in which plot selection is based on probability proportional to size (numbers of trees) are apparently more efficient than methods employing simple random selection. An estimated mortality rate 41 of 1.5 trees per acre was indicated, and estimates of 9.8 dead goodtopped trees per acre plus an additional 9.5 green high-risk trees per acre were found. Most mortality and tree decline were associated with disease agents, and continuing or accelerated disease-caused decline is expected in the area. Western white pine,lodgepole pine, and Douglasfir accounted for over 90 percent of the recent and older mortality. The widespread occurrence of destructive root pathogens, including Armillariella me flea and Poria weirii (identified on high-risk trees during the survey), indicates that even though tested control measures are unavailable, best available alternatives discussed herein should be considered in management of the area.
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