| Popis: |
On the Ground • Ecological and economic thresholds are important considerations when making decisions about safeguarding or restoring degraded rangelands. • When degradation levels have passed a threshold, most managers figure it is either time to take action or too late to take action depending on the particular circumstances of the case. • Considerations of ecological responses and thresholds have largely come from rangeland studies involving perennial vegetation with long-lived cycles of causes and effects, whereas thinking on economic responses to management and thresholds have often been informed by studies of weeds and pests in annual pastures and crops where cycles are fairly short and responses to control are generally fast. • In many cases of rangeland degradation, an asymmetry may exist between opportunities for taking action on the basis of shorter-term ecological signals and where that action will actually yield an economic response, which is often in the intermediate to longer term. • In many cases the time for economically warranted action is well past the point at which low-cost ecological control options exist, leaving only scope for higher-cost treatments or capitulation. |
