A weight estimate method for the determination of range or pasture production

A weight estimate method for use in determining grazing capacity was designed by the personnel of the Intermountain Forest and Range Experiment Station during the summer of 1936 after preliminary intensive investigative pasture and open range studies on sagebrush-wheatgrass ranges had shown wide variations to exist between grazing capacity calculated from plant cover density and that determined by grazing trials. The method was so designed that it might be substituted for density estimates in the point-observation plot method. By the weight estimate method, productivity of species of classes is estimated on permanent or temporary plots purely randomized, or located in a gridiron or patternized arrangement. Yield and floristic composition are recorded in units of weight. Estimates can be made on plots of any size or shape. The weight estimate method was tested in conjunction with square-foot density estimates on grass and weed types of vegetation in the Upper Snake River plains of Idaho. Under test, estimates by the weight method proved definitely superior to estimates of square-foot density in accuracy of indicating actual yield of different species or of different types of the same species. Error of density estimates was found to lie in the relationship between density and herbage yield. As such, it cannot be readily corrected. Weight estimates are accurate, indicative of yield, subject to actual mechanical check, rapid, and thus suited for use with replicated mechanically or randomly located plots, and the technic is easily learned with a minimum of instruction. Range or pasture productivity as well as floristic composition are expressed in terms of grams, pounds, or tons and as such are readily understood by the average layman and are synonymous with terminology used in feedlots and feeding experiments. Because data obtained by this method are comparable regardless of location, type of vegetation, or species, they will furnish a sound basis for stocking or management plans of any area. Forage inventory, percentage utilization, and palatability, the three standards in range investigations, are on an identical basis affording close correlation and integration vital in estimating grazing capacity. The weight estimate method on plots of any limited size or shape located in patternized mechanical arrangements or purely randomized may provide an excellent instrument for use in vegetative studies. It should be considered for use where records of vegetative changes, due to climate or grazing, are being maintained or where carrying capacity studies are being made.