| Area | Description |
|---|---|
| Work practice or system | Methods used to reduce damage to retained trees while the harvester is working. |
| Problem | There is always the chance that retained trees will suffer some damage while the harvester is removing and processing thinnings. Forests NSW allows a certain percentage of damage to retained trees, depending on the slope of the ground and density of the trees. For example, if the slope is 10 to 15% and the residual stocking is 160 stems per hectare, the maximum amount of damage to the retained trees in 10%. Forests NSW allows a further 5% damage if there's an unusual number of obstacles to cope with. However, we were suffering more damage to retained trees than we would have liked – mostly caused by the harvester bumping or scuffing the trees while it was working. |
| Analysis process | I inspected the retained trees after the harvesters and forwarders had finished in the area to look at the types of damage that was occurring. Then I watched the operators while they were working in the next coupe to see what was causing certain types of scuffing. In addition to these observations, I examined the Forests NSW reports and audits to see what the percentage figures were for the damage. |
| People consulted | Harvesting operators – to talk about the problems they were having, the causes of the scuffing, and proposed solutions. Forwarder operators – to see if they thought that the outrows weren't wide enough, or that there was some other contributing factor. Supervising Forest Officer – to discuss his reports and the figures he was calculating for the percentage of damaged retained trees. I also asked him for his views on possible solutions to the scuffing problem. |
| Objectives | To reduce the amount of damage to retained trees caused by scuffing from the harvester by two percentage points. That is, if our average damage figure for a particular area is 12%, we would try to reduce it to 10%. |
| Proposed solution | To leave more 'guard' trees in place while the harvester is removing and processing thinnings. The guard trees would shield the retained trees from impacts with the harvester itself and the trees being felled. Once the processing had been completed, the guard trees would be removed. |