Computerized technique for the assessment of plant utilization by herbivores

TitleComputerized technique for the assessment of plant utilization by herbivores
Publication TypeConference Paper
Year of Publication1998
AuthorsHyder P.W., Fredrickson E.L., Estell R.E., Havstad K, Remmenga M.D.
Conference NameSociety for Range Management Meeting
Date Published1998
AbstractA digital-photographic method was developed to determine degree of plant herbivores. Forty alfalfa plants were used to develop predictive regressions was photographed from two angles, 0 and 90, for baseline values of area. Samples approximating volumes typical of sheep bites were then removed from each plant. After each sample was removed the plant was again photographed from both angles. This was repeated until the entire aboveground portion of the plant was removed. Two methods were used for sampling; (1) removing leaves and stems simultaneously, (2) removing leaves only. The resulting photographs were digitized and loaded into a graphics program that allowed pixel area to be determined. A random coefficient model was used to calculate the relationship between sample mass and pixel area. Analyses were performed on 0°, 90° and both angles combined. The combination of the two proved to be the best predictor of mass removal. The confidence interval widened as the proportion of material removed increased. Although accuracy and precision was appropriate for some applications, several planned modifications should increase accuracy and ease of the method.