Forest inventory

A forest or forest inventory is carried out to detect large-scale forest conditions and forest production opportunities. The inventory is carried out on a random basis, mostly in selected sample groups. For example, tree species, age structures, growth and ownership conditions as well as wood stocks are recorded. Repeated implementation at certain time intervals allows statements to be made about forest developments (see also longitudinal study ). The results are the basis for forest, trade and environmental policy planning and decisions. Inventories at company level provide the data basis for forest management , the framework planning of public and large private forest companies. Other regular inventories are carried out as part of the forest condition assessment .

Forest enterprise inventories

Forest enterprise inventories record parameters of (mostly immediate) economic importance. A distinction is made between temporary and permanent inventories. Temporary here means that the exact location of the sample groups can vary from inventory to inventory because, in contrast to the procedure for permanent inventories, they are not marked in the long term. The permanent method therefore enables the creation of time series based on the development of individual trees and has fewer errors. In temporary inventories, the 6-tree sample is often used , while the permanent one uses concentric sample circles with different minimum values as the lower recording limit. The sample network is usually systematically attached to the Gauss-Krüger coordinate network and evenly distributed. The distance between the sampling points is 100 to 200 meters.

Different parameters are recorded. The most important are the tree species, the diameter at chest height , the age of the trees and the sociological position in the stand. Individual height measurements of the trees are carried out to create an upper height curve. With these values, sufficiently precise predictions can be made about the growth of wood in the forest within a time interval of around ten years. In addition, damage to the trees is recorded, which has a negative effect on the value of the wood. Another important parameter is the presence of regeneration separated by tree species and height. If this is the case, one normally determines how severely the young sapling are damaged by the browsing of roe deer (browsing report). Individual ecological aspects are also taken into account, such as the amount of dead wood in the sample circle , soil compaction through driving, a typification of the ground vegetation and the presence of habitat trees .

Forest condition inventories

Since the early 1980s, inventories have been carried out on behalf of the federal states in the course of the then apparent disease patterns of forests in Central Europe, which record ecological parameters. The terrestrial forest condition inventory (TWI) records the health status of individual trees using externally recognizable features. “Terrestrial” means that the acquisition takes place from the ground (and not, for example, by overflying or by earth observation satellite ). As a rule, the foliage (needling) of the crowns is recorded (i.e. estimated from the ground by visual inspection). The soil condition survey is part of this forest condition survey.

National inventories

Germany

In 1970/71, the first state-wide forest inventory was carried out in Bavaria. From 1986 to 1989 a nationwide inventory was carried out , which was repeated between 2001 and 2003 after the reunification of Germany . A third national forest inventory took place in 2011 and 2012.

Austria

In Austria, surveys have been carried out on a systematic sample network since 1961. In addition to economic key figures, ecological parameters are also primarily collected. The first follow-up survey took place in 1986/90, followed by more in 1992/96, 2000/02 and 2007/09. The Austrian Forest Inventory was known as the Forest Inventory until 1990 and is carried out by the Federal Research and Training Center for Forests, Natural Hazards and Landscape (BFW) on behalf of the Ministry of Life.

Switzerland

In 1981 the Swiss Federal Council decided to carry out the first national forest inventory (NFI) . In 1993, the legal basis for implementation was also anchored in the Federal Act on Forests (Article 33).

The recordings were made in 1983–85 (LFI1), 1993–95 (LFI2) and 2004–2007 (LFI3). In the LFI3, the forest landscape was also increasingly included.