There are many stages that a commercial forest plantation will go through on its way to becoming a timber harvest. In Irish forestry, the natural lifespan of a commercial coniferous forest is about 35 to 40 years.
At the beginning stages of the forest development is ground preparation and planting. Then comes a maintenance period where the trees are given as much help as is necessary to ensure that the majority of the plants have a chance of surviving against the encroaching and competing vegetation. The third stage of the forest development is first thinning.
This stage of the coniferous forestry development requires that many of the trees are extracted. In Irish coniferous forestry this means that one third of the entire crop is going to be removed. Removing the trees in this way achieves the result of allowing the remaining trees to grow and have a much larger share of the available nutrition and sunlight.
If this thinning process was not carried out in the forest, the individual trees would continue to grow upwards but would have no real growth in volume. It is the volume of the timber in the trunk of a tree which gives that particular tree its value.
The problem is that once a commercial plantation reaches a certain age and the trees close in on each other and it is almost impossible for an individual to reach the inside of the forest. Forest access is essential at this stage in order to determine whether the plantation is right for the first thinning process.
So, the answer is to open forest inspection lines. The forest inspection lines are placed in the forest at intervals of 100 meters around the perimeter. This provides a grid on the interior of the forest allowing a thorough inspection within 100 meters of any one point.
The forest inspection lines are cut by using a chainsaw. The process involves cutting the bottom branches from a line of trees all the way through the forest. The establishment of these inspection lines means that an individual can walk through the forest unimpeded.