Tests 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 × 50 cm. The number of quadrats harvested can be substantially reduced by improved observer rating.

Using the dry mass rank method and 240 quadrats of 50 × 50 cm, percentage contributions to above‐ground her‐beceous yield in terms of dry mass for all species were estimated to within ± 5 percentage units of their harvested value (P 0,05). Sixhundred quadrats were sufficient for estimating to within ± percentage units. Estimates from quadrates of 25 × 25, 25 × 12,5 and 12,5 × 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.

Uittreksel

Die bo‐grondse planteoes is vasgestel deur vergelykende oes metode tot ± (p < 0,05) van die geoeste gemiddelde deur 150 geoeste en 600 standaarde kwadrate van 50 × 50 cm te gebruik. Die getal geoeste kwadrate kan heelwat verminder word deur verbeterde waarnemende standaard.

Deur die droë massa rank metode te gebruik met 240 kwadrate van 50 × 50 cm is persentasie skatting van die bogrondse planteoes in terme van droë massa vir alle soorte vastestel tot ± 5 persentasie eenhede van nulle geoeste waarde (p 0,05). Ses honderd kwadrate was genoeg om tot ± 3 percentasie eenheide vas te stel. Uitslae van kwadrate van 25 × 25, 25 × 12,5 en 12,5 × 12,5 cm was minder akuraat. Deur ranke totale planteoes gewig vir elke kwadraat te gee het die skatting aansienlik verbeter.

Samegebruik van die vergelykende oes en droë massa metode stel ons in staat om botaniese komposisie in terme van massa uit te druk. Beide metodes het die voordeel dat hulle vlug is.