Grass Surveying

Grass surveys are completed on an annual basis here on the reserve as a very useful conservation tool. There are 25 randomly selected GPS sites across the reserve, each covering a 100m, 200m, or 300m long section. When completing each grass survey, the researcher must follow the correct direction for the set distance and record all grasses present within one metre each side of the middle line.

Grasses have developed through natural selection to deter, escape and tolerate herbivory, and to escape and tolerate fire (especially in SA). Today, grass species are classified as increaser I, II, III or decreaser species, depending upon their tolerances. Increaser grasses increase in abundance following grazing, whereas decreaser grasses decrease with exposure to heavy grazing. In short, grasses that animals prefer to eat (due to higher sugar levels etc) are eaten first and so these decreaser grasses become fewer and fewer. They are then replaced by increaser grasses which have not been eaten, and unwanted grasses then become more abundant. If this occurs on a grand scale, it has the potential to lead to unhealthy game and livestock.

From our data collected we can analyse the results to determine the total percent coverage of each grass, as well as the percentage of increaser and decreaser grasses present. This, in turn, influences the number of game that can be kept on the reserve (stocking density). For example, a reserve with a higher percentage of decreases would be able to keep a much larger and healthier amount of game compared to another reserve of the same size with a lower percentage of decreases. The more increasers there are, the fewer number of game can be kept.

Analysis of the results we have collected thus far indicate that there are a high number of decreases on the reserve which is very positive. We only have a few more grass surveys to complete and then we will be able to analyse all of the data and come to a final conclusion on the overall health of the reserve. Fingers crossed for a good outcome!