Sequential sampling protocol for monitoring pasture utilization using stubble height criteria

Abstract

Stubble height, a measure of the amount of vegetation remaining after grazing, is thought to be a useful variable in the management of riparian areas. A number of riparian and grazing processes appear to be directly or indirectly affected by the residual stubble height. Thus, average stubble height is often used to evaluate the livestock impact a pasture has received, particularly in riparian zones. Stubble height sampling methodology has received little previous attention. A sequential sampling procedure for stubble height was investigated. The procedure provides statistically defensible answers in the shortest possible amount of time. The procedure does not require a rigid sample size and involves simple yes/no answers at each observation. A small initial sample of readings is selected and evaluated. If there is sufficient information to make a clear decision, then grazing is either continued or stopped. If the initial evidence does not clearly support either decision, then sampling proceeds. This may continue for several iterations before a decision is reached. Statistically supportable decisions can typically be made within a short time frame using this method. This method may also be applied to evaluate trampling and other yes/no responses.