Sampling Error in Range Surveys of Sagebrush-Grass Vegetation

One major objective of a range survey is to determine the forage cover, as a basis on which to estimate grazing capacity. However, it is extremely unlikely that the estimated forage yield of an area will coincide with the actual yield, even if methods of measuring vegetation are without error, and if individual members of survey crews are mechanical in their precision. If sampling units are drawn correctly, however, an estimate of the magnitude of the difference between the estimated and actual yield and the likelihood of the occurrence of such difference is provided by the unbiased estimate of sampling error. An unbiased or representative estimate of sampling error also provides appropriate information for estimating the number of sampling units (plots) needed to attain arbitrary limits of accuracy in future surveys on similar range areas.