Technique to study the impact of large herbivores on woody vegetation within piospheres

Abstract

A continuously sampled transect away from a watering point provides good results in situations where geology and soil type remain constant, but is unsuitable to apply where regular changes in soil type occur. A comparison was made between a continuously sampled transect and sampling taken at intervals along the transect. An analysis of variance indicated no significant differences in any of the variables obtained by means of the two sampling methods. The advantage of interval sampling is that, within each zone, areas with the same soil type can be selected in order to avoid environmental heterogeneity. A comparison between transects made in different directions from the watering point yielded no significant differences in any of the structural variables of the woody vegetation at the same distance from the watering point. Therefore, combining transects from different directions to attain a representative sample away from the watering point was an acceptable practice. It is recommended that the original data be smoothed and the logistic function used to model the impact of large herbivores on the structure of the woody vegetation around watering points.