Evaluation of the wheel-point and step-point methods of veld condition assessment.

Abstract

A number of aspects of a technique recently developed to assess the agro-ecological condition of veld were evaluated by 4 independent observers. Measuring the veld composition score yielded relatively repeatable results with a 95% confidence limit of (6,43 units for any single estimate which may range from 0 to 100 units. The step-point method yielded results on percentage veld composition and on veld composition score which did not differ in precision or in absolute amount from those obtained using the wheel-point apparatus. Adoption of the step point method in preference to the wheel-point method saves in equipment and manpower, and renders the technique usable by extension officers estimate of basal cover, and perhaps should not be used on uneven terrain or bushy veld. Using a circular-quadrat 3,5 cm in diameter yielded a more precise index of basal cover than did the standard method using a point-quadrat 1 mm in diameter. However, there are disadvantages in using the relatively large quadrat. Possible bias introduced into determining percentage species composition and composition score by using the nearest plant method were negligible.

Keywords: basal cover; measuring; precision; quadrat; range; species composition; step-point method; technique; veld condition assessment; wheel-point method