Young timber stands, even when providing 100 percent visual concealment for elk when viewed on a horizontal plane, may provide 50 percent or less cover when viewed from an opposing slope at an elevated viewing angle. The higher the viewing angle, the greater the relative cover loss. In a simple linear model, viewing angle explained 52 percent of the variation in hiding cover values. Slightly more variation was accounted for when the data were stratified by tree height. On the average, for a 10-degree elevation in viewing angle, hiding cover decreased by 10 percent. The cover loss relationship was most pronounced in stands with the steepest topography, the shortest trees, and the lowest tree and shrub densities.
United States Department of Agriculture, Forest Service, "The Influence of Viewing Angle on Elk Hiding Cover in Young Timber Stands" (1986). Forestry. Paper 37.