Questions & Answers: Woodland management webinar - 03/06/2020
In a lowland setting, to what extent should bramble be managed in a douglas fir/larch PAWS site?
In a forest at equilibrium the stand structure will consist of, different sizes of regeneration, poles and shrubs that all make up the intermediate layers. This vertical structure intercepts a lot of the light passing through the open canopy and controls bramble and other plants that compete with regeneration.
In transformation the middle layers may be missing or poorly developed so regeneration may not become established due to weed competition (brambles, bracken, etc). In some cases, a solution is to be proactive and to select small groups where there is light on the ground, cut back the bramble with a brush-cutter and then plant small groups of transplants. This can be done over very small areas and with small numbers of plants. The plants may need weeding during the first growing seasons for two or three years until the leaders are above the brambles.
The groups will control the bramble within the group and affect the diffuse light under the canopy as they develop and become a dynamic element within the structure of the woodland.
Is the GD thinning pattern applicable to a broadleaf ancient semi natural woodland?
GD was designed for conifer plantations in transformation to continuous cover forestry (CCF). It is cost effective and it initiates horizontal irregularity and an element of vertical structural irregularity. It is also a mechanism to manage the risk of windblow. All these characteristics may apply to a young broadleaved wood in transformation to CCF. The selection criteria and the thinning cycle will be different, but the thinning design can be the same. The same principles will apply, creating a permanent infrastructure and establishing extraction racks into which the selected trees are felled. The first two stages of GD have closely spaced extraction racks. If the spacing is 2.0m then the rack centers are at 16.0m at T1 and T2 (8.0m apart if you consider the old T1 rack). As more and more thinning takes place over time you need to space the racks further apart by abandoning middle racks. 1 in 8 (16.0m) will become 1 in 16 (32.0m). As the racks get further apart the same rule about machinery never leaving the rack is maintained, so trees selected out of reach of the harvester boom need to be felled by chainsaw towards the racks and processed on the racks.
Does the use of tracks and machines work on ore challenging ground?
The more challenging the ground the greater the difficulties in extraction and the greater the costs of harvesting. There comes a point when the value of infrastructure development is outweighed by the increase in costs and the environmental damage and loss of productive ground as the track intensity increases. Tracks are always necessary but, the design and the intensity of the lay-out will be determined by the harvesting method, harvester/forwarder or tractor trailer or skyline.
Do you need to use chemical control or just the dollop system works enough?
This depends on site conditions. Dollop planting may need no weeding at all. On other sites the weeds may germinate very quickly and smother the plants so some form of weed control will be required to get the trees established. Chemical or hand weed may be required.