A Problem Tree to Diagnose Problem Bush

The term “problem tree” refers to a conceptual model used as a diagnostic tool to analyse a sequence of events that leads to a problem (such as bush encroachment in rangelands). A problem tree is useful because the consequences of different interventions can be visualised and understood more easily in diagrammatic form, thereby guiding management decisions regarding the problem. A problem tree was constructed to show multiple causes of bush encroachment. It was generalised by considering many possible causes, and not only those applying to particular areas of encroachment or specific species of bush. If the problem tree is to be useful in decision-making, one needs to determine which of the multiple pathways are of greater significance in any particular situation. Management decisions are bound to be more effective in the long run if they address causes higher up in the tree and closer to the root causes, than the proximate causes or symptoms at the bottom of the tree.