The reforestation by planting is the sole method used for the Douglas.
Planting is one technic which allows benefiting from genetic improvement.
This genetic benefit improves the productivity of the Douglas.
Earth-balled plants: Planting the Douglas grown in earth-ball is fairly recent. It represents today 10 % of the Douglas reforestation in France.
As part of a reforestation by planting, the quality of the root system of the earth-ball plant is vital. Openwork plant plugs must be favoured (with integral self-encircling and roots buds pending growth).
For the Douglas, open-work plant plugs with no bottom must have sufficient volume (1 year: > 200 cm3; 2 years: ideally 400 cm3) to get young plants without any roots deformations (roots well ramified and without buns or constriction) and guarantees superior restarts, a more stable integration and a better water supply.
Earth-balled plants allow:
- a sounder logistic less traumatic for the plant,
- time benefit : no need to place in a seedbed, quicker planting if the soil has been prepared,
- a better restart : immediate growth, reduced perspiration of the smaller plants, possibility of always planting fresh plants,
- a larger planting period: from February to end of May.
Prepare your project:
It is important to draw up a diagnosis of the reforestation site.
The objective is to adapt the reforestations’ technics to the singularities of the plots (ploughing technics, fertilisation, planting density).
Reforestations' steps:
The ground’s preparation is vital when the planting area already has the competition of existing plants or too bulky, long- lasting cultivations.
- after clear-cutting, on a bare or sloppy ground: wait for 1 or several years the natural return of ligneous colonisation (Mountain Ash, Birch tree, Willows, semi-resinous trees…) and semi-ligneous (Brambles, brooms, Blueberry bushes….) then proceed to open up, either by narrow tracks with a strimmer or by larger strips using a gyro-crusher, and this in readiness to facilitate planting and the restart of the Douglas under lateral shelter,
- On a meadow or on a dense carpet of grass in a forest: lacerate the roots’ felt of the grass layer by a mechanical ploughing of the stubble with a cover-crop or hoeing using a chisel.
Working the soil before planting is usually beneficial, with significant growth’s benefits during the first 3 to 5 years.
Choice of the planting’s density:
The initial planting density of pure Douglas or mixed Douglas must be responsibly thought according to several factors:
- The silvicultural objectives,
- The genetic quality and the plants costs,
- The fertility and the area constraints, the slope and the spot accessibility,
- The presence more or less strong of game,
- Nature and competition from existing plants,
- The eventuality of a mechanical maintenance later on.
In mixed plantations, the objective is also to achieve while clear-felling a selection which aims to keep 150 to 200 of the best specimens per hectares.
High density: 2000 plants / hectare, that is to say 2.5 m x 2 m (3x2)
They are justified in some situations: 1. The lack of availability of high quality equipment, 2. Reforestation of bare ground, without any lateral shelter or hope of natural resurgence of ligneous plants, 3. Strong local pressure from game, 4. Local climatic risks : strong wind, late frost, 5. Strong competition from existing plants : grass, ferns..., 6. Shortage of qualified workforce for the maintenance and improvement.
Medium density: 1100 per hectares (3X3) to 1600 per hectares
There are possible in different circumstances: 1. Genetic guarantee of the plants (qualified equipment) of high quality (young, vigorous, selected, fresh...), 2. There is a natural ligneous recrudescence available or potential presence of accompanying species to raise the targeted trees, 3. Lack of game or individual protections, 4. Sloping ground, frequent obstacles, 5. Forest paths used by motorised machines.
Planting:
When planting the plant plugs, the roots keep their entirety and they are relatively well protected from degradations or drying out. Hence, if the temperature and humidity conditions are favourable and if the soil’s preparation has been well done, roots can restart their growth and develop outside the plant plug; without any stopping of vegetation, the restart is usually excellent.
- Supply the working site daily and avoid any drying out of the earth-balls: store them under a shady shelter and humidify them regularly.
- Respect the following instructions:
- bury the earth-ball in the soil well to avoid the evaporation of the water it contains and this all the more so as the ambient air is hot and dry,
- to avoid « the strands effect », cover totally the surface of the buried earth-ball with 3 to 4cm of soil,
- tamp down the soil slightly: do not damage the roots’ system of the plants.
Période de plantation :
jan
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
Using the earth-balled plants 200 cm3 allows planting after the strong winter frost.
The planting period is much longer than for the bare-rooted one.
Planting rules:
- Usually, The Douglas is planted in the spring so as to limit the risks caused by frost.
- Do not handle, or plant earth-balled plants in frosty weather.
- Adapt the planting hours and monitor the plants humidity according to the weather and the reforestations periods.
– Cover up the earth-ball well without pressing or tamping down.
- Ensure the plant is placed in straight (rectitude).
