The timber stock has increased. Today, the forests contain more large-girth and less thin trees than ten years ago.
Among trees under 30 centimetres Diameter at breast height (DBH) the timber stock dropped. Almost all of the stock increase is among large-girth trees from 50 centimetres DBH. In the meantime, 23 % of the total timber stock is trees with a DBH from 50 centimetres. This share is particularly high in heavy timber among fir (48 %), oak (42 %) and beech (38 %).
This indicates a continuation of a trend that was ascertained as early as the 2002 National Forest Inventory. If this trend continues, based on the age structure of the forests we can expect that the heavy timber will increase in coming years in above-proportional amounts. This development is a challenge because the processing capacities for heavy timber have diminished due to the specialization of the timber industry in small to medium sized trees. There are indications that the supply and demand of heavy timber from the timber industry are increasingly divergent. It is presently unknown whether these timber assortments may possibly be used more for energy production or, through new technologies, for the production of materials, or whether heavy timber will increase further in the forest.
However, the fact is that for the forestry holdings, a rise in the age of trees increases risks during harvesting (e.g. caused by crown deadwood), the risks of timber devaluation due to fungi and insects as well as the probability of species protection-related restrictions. A development leading to many of these large-girth trees remaining in the forest until they decompose can, on the one hand, promote the biological diversity of the forests, but on the other hand it reduces quantities of available raw wood and the potential of binding the greenhouse gas carbon dioxide for the long term in timber products.
A forestry policy aligned to the principle of utilization and conservation must weigh the balance between the services and demands of the forest in a constant dialogue with forest owners, nature conservationists, the timber industry and society. Findings from research and development supply important foundations for this.