Sunday, August 21, 2011
Following the tracks: 2. Branch Roads
There are three types of road that you should find in a forest landscape. We have looked at main forest roads. Next there are branch roads that leave the main road to provide a secondary artery to a tributary valley or to service one side of the valley. Branch roads are sometimes called collector or feeder roads. They provide access to logging or spur roads that provide access for harvesting and tending.
A good system of branch roads in the landscape indicates planning for the future. A planned forest road network in the landscape will have less roads in total and less steep roads than a network that just develops over time. Forest road networks that just develop as the next area is harvested tend to be haphazard. There is usually too much road and more steep roads than necessary. Systematic forest road networks are more sustainable because they are less costly to maintain and do less damage to the environment.
The branch road in the photo above is an example of a well located stable branch road. The road was located probably over 40 years ago on a high rainfall area of the BC coast. It has recently been reopened by brushing the vegetation on the road sides. The original surface, road drainage are all in good condition and the road has been returned to service at minimal cost. It is a sustainable road with relatively gentle gradients. The road was located by a forester or forest engineer in the days before the environmental awakening brought environmental protection regulations and forest practice codes. Although the road was not deactivated with protective water bars, it remained stable for decades.
The forester or forest engineer that located the road overcame a major terrain challenge. The road is a branch road that gains entry to a hanging valley that meets the main valley at a higher elevation. Hanging valleys are a common feature in BC's glaciated mountainous terrain. A common error in road location to hanging valleys is to attempt to gain entry with locations that are too steep. He found a location that fitted the landscape, provided a gentle gradient and has proved to be stable and sustainable. Part of the location went through an area of timber that would have been considered undesirable 40 years ago. The area was not harvested until recently. He did a good job and probably took considerable criticism from his logging managers of that era, for locating a length of road through an area that would not be harvested.
This branch road is newly constructed. The terrain challenges are similar to those in the first picture, but this road is steep with the gradient reaching at least 18% as the road turns at a switchback. Imagine being the driver of a logging truck who has to negotiate this switchback with tens of thousands of kilos of logs behind him. Today's standards will be followed and this road will be deactivated by installing water bars. However, there will remain a considerable likelihood of erosion. This road built after a period of imposed standards and regulations is much less sustainable than the first road. The motivation in the case of the road the first picture came from the forester or forest engineer and the road was placed on a sustainable location on the landscape.
Conclusion Branch roads are a key part of systematic forest road networks. The presence of well located, stable branch roads is an indicator of sustainable management and thought for the future.