Qualify-Dimension
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Qualifying-Dimensioning ("QD") is a near-natural silviculture strategy. The aim is to produce valuable wood in the multifunctional forest with the least possible effort.
Silvicultural orientation
QD adapts to natural development phases of forest structures and trees and does not work with constructed models. To designate the phases of tree growth, terms are used that characterize important silvicultural subtasks on the way to valuable wood .
Silvicultural measures are designed to be effective in terms of points and fit into the natural dynamics of the forests; there are no extensive interventions.
The aim and trademark of QD are trees with the mighty crowns immediately above the value trunk. At the time of harvest, these value trunks should have at least 20 cm wide, knot-free wooden shells with lengths of around 25% of the tree heights then reached.
Development phases
From a forestry point of view, the QD strategy differentiates between different development phases. These are characterized by conquering the treetops, internal and inter-species competition and efforts to reproduce.
Establishment phase
This includes the first years of life of the trees. It begins with the germination of the seeds or planting and ends when the young tree has definitely prevailed against competing plants in the vegetation structure.
Qualification phase
As soon as the young trees have outgrown the competing vegetation and enter into intense displacement competition with one another, the qualification phase begins. The trees are now growing faster and faster and natural branch death begins. In the qualification, tightness promotes natural differentiation , the dying of branches should proceed as quickly as possible. Sufficiently good and at the same time supervital young trees should grow into trees that are suitable for wood. Ecologically and aesthetically valuable trees are specifically taken into account.
Dimensioning phase
It starts when the branch die has reached the desired height. A guideline for entering this phase is a trunk length free of green branches of approx. 25% of the possible final height. In the dimensioning, the natural systems for the formation of the knot-free valuable wood on the selection trees should be brought to full development. Thanks to their silvicultural support, these should grow into thick, stable trees of value. The selection trees are selected and marked according to the criteria of vitality and quality. The required distances between selection trees are derived from the crown diameters of harvest-ready, large-crowned trees for a specific species. A pruning measure may be associated with the selection and exemption of the readout tree. In the dimensioning phase, all silvicultural interventions are limited to removing the aggressors from the selection tree. The time available for expanding the crown is limited! The tree crown is dimensioned and the dying of branches is brought to a standstill until the tree is harvested. QD's trademark is a permanently suspended crown base.
Maturity phase
After a tree has exceeded 75-80% of its final height, it enters the maturation phase. The increase in height then usually noticeably decreases, and so the ability to spread the crown is only minimal. After contact with the crown between mature trees, there is hardly any branch death. These trees have "arranged" and "get along with each other". At the end of the ripening phase, valuable wood is harvested, trees with important biotope properties (biotope, old and dead wood) are left. At this point, the new generation of forests should already be established.
Age and Decay
The decisive step towards closeness to nature in forest management is the inclusion of the age and decay phase. Here, the QD strategy links its timber-oriented economy with the forest ecosystem and its abundance of species.
literature
- General forest journal / Der Wald No. 5/1999, Georg Josef WILHELM, Hans-Albert LETTER, Walter EDER, pp. 232–240, conception of a near-natural production of valuable wood
- Georg Josef Wilhelm, Helmut Rieger: Near-natural forest management with the QD strategy. Ulmer Verlag, Stuttgart, 2013, ISBN 978-3-8001-7858-2 .