Graminoid basal cover and biomass estimations in the Brotherton burning trial

The contribution of grass basal cover is an important measurement in rangeland science and is known as a proximate for grassland functional health and general range condition. Increased basal cover of grasses contributes to improved infiltration and reduces sediment losses. The importance of the Maloti-Drakensberg mountain range for water production has been emphasized and interest into the factors that influence basal cover and associated water delivery have followed. Measurements of basal cover in the Drakensberg have however, been constrained by timeous and inaccurate measurements (esp. the Hardy & Tainton (1993) method) associated with common techniques. This basal cover data was collected using a quadrat based technique which may be conveniently coupled to estimating herbaceous biomass. The method was tested on the Brotherton fire trial. The method is straight forward. A quadrat of 0.500x0.500 m with 10 cm divisions along horizontal and vertical axes gives 25 sub quadrats each representing 4 % of the area covered by the quadrat. Therefore, basal cover in the 25 sub quadrats can be scored from 0 – 4 % in increments of one then, the total summed to give percentage basal cover. To improve the visibility of basal cover quadrats should be clipped before estimating basal cover. Furthermore, clippings may be weighed for estimation of herbaceous biomass. A CyberTraker application for recording the data has been developed for field use. Photos were taken of each quadrat making data verifiable by viewing photos. For the purposes of this verification, sub quadrats were consistently recorded from left to right, beginning at row one to five in the quadrats (see labelling in fig. 1). A pilot study indicated that between six to eight quadrats per sample area (or treatment) are required. By placing six quadrats per plot at Brotherton, basal cover was estimated in the Brotherton field trial. Clippings were collected so that herbaceous biomass could be estimated. Sampling was done in winter after the autumn and winter burns, in these plots clipping was not necessary and biomass could not be collected.