Abschätzung von Verjüngungsdi­chten und Analyse wirksamer Ein­flussfaktoren auf die Verjüngung von Zielbaumarten auf der Basis von WISA-Daten

In the past, single-layer, even-aged conifer stands of Norway spruce and Scots pine that were not suitable for the site were established on a large scale (ZERBE 2009). These stands are particularly worthy of conversion as they are susceptible to calamities caused by storms and bark beetles and have a negative impact on the soil function of the sites (WERMELINGER, 2004; EISENHAUER and SONNEMANN, 2009; JÖNSSON et al., 2009). Since 1992, Saxony has been striving for increased forest conversion to structurally rich, site-adapted mixed forests (Butter 2001).
One way of achieving the forest conversion goals is to promote and manage natural regeneration (HERING et al. 1999; FISCHER et al. 2016). In particular, the spread of deciduous trees as part of stand succession and their inclusion in the specific silvicultural management objective should be taken into account. Hering et al. (1999) cite the example of pure pine and spruce stands, in which an immigration of site-appropriate deciduous tree species takes place with progressive loosening. Depending on the spatial and temporal intensity and quality of natural regeneration, the cost-intensive artificial introduction of site-appropriate tree species may even be unnecessary to achieve silvicultural objectives.
The aim of the research project presented here is to identify natural rationalization potentials in forestry operations by including spontaneous natural regeneration in forest conversion. Knowledge of the spontaneous regeneration of tree species in relation to their spatial distribution in the overall forest of Saxony and the respective structure of the forest stands is of particular importance here.
Sachsenforst has decided to carry out the inventory on the basis of a permanent random sample (WISA). Initial results from this sample are available for individual forest districts, which also contain regeneration data. A static estimation of the occurrence and density of established beech, oak and rowan natural regeneration is to be carried out, taking into account the data structures of the Saxon permanent sample inventory. The establishment model developed and parameterized for this purpose serves as a forecasting tool for the spatial estimation of regeneration density in the state forest. With the help of these predictions, spatial decisions on forest conversion activities can be planned. At the same time, it will be investigated which of the (primarily ecological) factors influencing the establishment of regeneration are of particular importance.