Test of two methods for determining herbaceous yield and botanical composition.

Abstract

Above-ground herbaceous yield was estimated using the comparative yield method to win + 10% (p < 0,05) of the harvested mean using 150 harvested and 600 rated quadrats of 50 x 50 cm. The number of quadrats can be substantially reduced by improved observer rating. Using the dry mass rank method and 240 quadrats of 50 x 50 cm, percentage contributions to above-ground herbaceous yield in terms of dry mass for all species were estimated to within ( 5 percentage units of their harvested value (P 0,05). Six hundred quadrats were sufficient for estimating to within ( percentage units. Estimates from quadrates of 25 x 25, 12,5 and 12,5 x 12,5 cm were less accurate. Weighing of ranks by total herbaceous yield for each quadrat significantly improved estimates. Use of the comparative yield and dry mass ranks methods together enables botanical composition to be expressed in terms of mass. Both methods have the advantage of being rapid.

Keywords: botanical composition; colophospermum mopane; dry mass; method; savanna; yield; zimbabwe