The Federal Forest Inventory (BWI) is a project jointly sponsored by the federal government and the states, which is ordered by the Federal Ministry of Food and Agriculture and is repeated every ten years. Previous inventories covered the years 1987, 2002, and 2012. In addition, carbon stock data were still collected in 2008 and 2017 in a sub-sample of the BWI. The following basic data are particularly relevant in the BWI: Tree species, tree diameter, tree height, regeneration, stand structure, deadwood, and land use before or after forest. In total, over 150 characteristics are recorded. These recorded data are then used to calculate a wide range of statistical data on forests in the federal states and throughout Germany. The most important of these are: Forest area, wood supply, wood increment and wood utilization, tree species diversity, age structure and closeness to nature. Ultimately, the current state of the forests and their changes or transformations since the last inventory are to be derived.

BWI is a central database for the German forest by providing an overall view of large-scale forest conditions and forest production possibilities. Only the BWI provides an essential knowledge base for sensible climate and environmentally friendly action. Together with the Federal Forest Inventory, the Carbon Inventory is an up-to-date database for international greenhouse gas reporting based on the Framework Convention on Climate Change and the Kyoto Protocol. From its data, information on biomass and carbon storage in the forest is derived, and the changes in land use of and by forests are recorded. In combination with the WEHAM model (forest development and wood supply modeling), it is then possible to assess how the CO2 storage capacity of forests can be influenced by different factors and scenarios. In combination with climate models, experts can finally assess to what extent our forests can cope with climate change and where risks exist.

In species conservation, the findings provided by the BWI are also important: as already mentioned, the diversity of tree species is one of the basic data that must be recorded. However, the forest inventory also determines how much deadwood exists in the forest, which serves as a significant indicator of species diversity in the entire forest ecosystem: numerous insects and fungi depend on deadwood. The data are therefore not only essential for climate protection; the extensive data collection also provides the basis for important guidelines for the protection of nature and wildlife, in that climate or nature policy at federal, state as well as European levels draws on them.

In addition to ecological and environmental policy issues, the data collected can also help with forestry and timber management decisions. For example, they provide information on the development of stands, species and quality of the raw material wood.