Stages of Forest Development / Stage of Maturity

Stages of forest development refers to sections of forest development in which forest trees are of a specific dimension. Definitions for differing stages of forest development are produced by the various Länder based on tree dimensions (diameter at breast height (DBH) and tree height) and age.

For assessment as a stage of forest development, an area involved must cover at least 10 percent of the assessment unit. As an exception, minimum coverage is reduced to five percent for clearings (temporary tree-free areas) and early-stage natural forest for them to count as a stage of forest development in their own right.

Apart from characteristic commercial tree species, stages of forest development may also comprise either, in whole or part, all other characteristic trees and shrubs such as pioneer tree species and shrub species (hawthorn and holly, for example). For assessment purposes, occurrence of characteristic trees and shrubs in other layers (understorey, midstorey and overwood) outside the main layer count as growth class if they meet the above minimum area requirements and their density matches at least 30 percent of a comparable full stock.

Maturity stages in forests are characterised by the occurrence of old, strong trees of a minimum density (stand density and crown closure).

Dead Wood

Dead trees, broken heavy branches and crown components with a diameter of > 30 cm for soft deciduous trees, otherwise diameter > 50 cm and height/length > 3 m.

[Diameter: DHB for standing trees; widest end for fallen trees/tree parts]

Alternatively, the Länder may also define threshold values as m3 / ha.

Habitat Trees and Old Trees

Habitat trees are:
a) Hollow and nesting trees
b) Trees with a DBH > 40 cm with rotted sections, peeling bark, bracket fungi and broken crowns (subject to modification by the Länder)

Old trees are usually more than 150 years old and are defined by tree species-specific minimum DBH. The Länder define the minimum DBH, taking into account the natural and location-specific conditions. The following shows the references used for old trees in good growth locations:
Beech, oak, high-value broad-leaved species and poplar: DBH > 80 cm.
Other tree species: DBH > 40 cm.