An ocular technique for estimating utilization of karoo bushes.

Abstract

A subjective technique for estimating utilisation of karoo bushes is evaluated and guidelines for its use are proposed. Taking the average utilisation from estimates on 30-40 bushes, 20% differences in utilisation could be distinguished as significant - even when different operators were used. Zero and 100% levels of utilisation were judged with greater accuracy and precision than intermediate levels. However, if more than 30 bushes are taken per sample the precision and accuracy at all levels is adequate. Acceptable levels of accuracy were obtained with fewer bushes than that required for adequate precision. Using similar sample sizes the ocular estimation technique was more precise and more accurate than objective techniques. Furthermore, this technique was far more efficient than any of the objective techniques.Language: English

Keywords: accuracy; botany; dwarf shrubs; karoo; karoo bushes; method; Ocular techniques; ocular-estimation technique; precision; south africa; subjective estimation; techniques; utilization