Tutorial

Dear Farmers and Resource Managers, Welcome to the Decision Support System (DSS). The model in turn was largely based on research done on the population dynamics of Acacia mellifera (now referred to as Senegalia mellifera; swarthaak; omusauna) in this vegetation type.

The EXPERT SYSTEM is divided into two types of decisions:

1. Adaptive decisions (these are opportunistic decisions which would only be relevant and useful during certain circumstances related to periods of exceptionally good rainfall, drought, and after frost (See Figure 1 and Figure 2). Making the right decisions at these times might be crucial in preventing large-scale transitions towards bush thickets (good rainfall), or thinning out of existing mature thickets (drought, after frost). In fact, we believe that removing the opportunities that come with these weather extremes is a major reason for the current encroachment situation.

2. Reactive decisions or decisions to treat the symptoms (these are decisions on whether to and how to, treat existing problems – i.e. areas already under dense cover of bush). The EXPERT SYSTEM includes actual methods of bush control, while recommending that it should be done in contour strips to regenerate water and nutrient cycling. We emphasise though that much of our rangeland is not bush encroached at this stage and can remain this way if ongoing good management and adaptive management are applied.