03284naa a2200193 a 450000100080000000500110000800800410001910000190006024500810007926000090016052027530016965000190292265000220294165000130296365000110297670000160298770000200300377300670302315201962023-03-31       1963    bl uuuu     u00u1 u    #d1 aSCHMUTZ, E. M.  aGrazed-class method of estomating forage utilization.h[electronic resource]  c1963  aAbstract: A grazed-class method of esti- mating range utilization com- bines the advantages of several systems in use. It is proposed for use in both administrative and research phases of range man- agement. The method is based on a pro- cedure which classifies grazed plants into six grazed-classes - 0,10, 30, 50, 70 and 90 percent use. Photographic guides, de- veloped from height-weight curves of average local plants, are used for each key species to guide the examiner in placing grazed plants into the grazed- classes. Representative samples of 20, 25, 50 or 100 plants, lo- cated by toe-pace transects, are estimated for each key species to determine the percentage of grazed plants in each grazed- class. Current utilization is cal- culated by multiplying the av- erage use factor for each grazed- class by the corresponding per- centage of grazed plants in each class and totaling the products. Based on this percentage of cur- rent use, plus data on the cow months grazed and proper use of the key species, the cow months remaining and the total proper use can be estimated by simple calculations. The method was tested against the weight-method and was found to be fast, simple, statis- tically sound and reasonably ac- curate. Estimates were made on two species, sideoats grama and black grama, representing a bunchgrass and sodgrass type growth. After only a few hours use of the method, statistically satisfactory estimates were made by both experienced and inex- perienced examiners. The use of photographic guides makes possible the estimaition of utilization based on forage re- moved (but also shows herbage remaining) and facilitates judg- ment of irregular grazing on the plant. Errors are compensating and guides can be easily checked against clipped weights. The method requires reason- ably close correlation between the photographic guide and (1) the height-weight curve of the average plant used to make the guide and (2) the growth form of the plants estimated in the field, but permits considerable variation in height of plants. The grazed-class method is easily adapted to use by ranch- ers, technicians or research workers. Many problems in uti- lization remain to be solved and the grazed-class method offers a tool to help solve these problems. Table 1. Grazed-classes and method of calculating current use by the grazed-class method of estimating utilization; Table 2. Utilization estimates made by various examiners using the grazed- class method compared to utilization determined from weight data; Table 3. Statistical analyses of utilization estimates made on sideoats and black grama by the weight and grazed-class methods; Figure 2. Relation of coefficient of variation of the mean to sample size black grama  aForage grasses  aForage production  aForragem  aManejo1 aHOLT, G. A.1 aMICHAELS, C. C.  tJournal of Range Managementgv. 16, n. 2, p. 54-60, Mar. 1963.