What data is available?
The Swedish National Forest Inventory (NFI) Riksskogstaxeringen started in 1923. The results of the inventory can be divided into three parts:
1923–1952: Two separate county wise inventories (1923–1929 and 1938–1952) performed as continuous belt inventories. During the second inventory, this was combined with sample plot inventory.
1953–1972: Annual inventory where 10 years of continuous data constitute a complete inventory. Inventory plots are grouped in clusters. Temporary plots only.
1983–: Same as previous period but here, 5 years of data constitute the whole sample. A combination of temporary and permanent sample plots.
The basic variables collected comprise tree data, sample tree data, stand characteristics, ground and field layer data. The number of variables has increased continuously, and the focus of the inventory has been broadened from a forest management perspective to a wide spectrum of ecological variables.
The inventory encompasses both direct measurements (such as tree counting and diameter measurements) and assessments (such as coverage percentage for ground vegetation). The coverage of field work has also widened to include protected areas and alpine areas.
How can I gain access to plot data from the NFI?
Since the Swedish NFI is a sample-based inventory, data is primarily used for different kinds of estimations used for National Official Statistics. Certain types of analyses, however, require information from individual plots. For example calibration and evaluation of remote sensing data and maps, and different types of modelling. A selection of the last few years’ temporary plots are freely available for download:
If you require older plot data or other kinds of information from individual sample plots, please contact one of our analysts to discuss your project.
When did the NFI start inventorying dead wood?
Dead wood in the form of dry and windthrown trees (suitable for firewood) has been measured since the Swedish NFI was initiated in 1923. An extended inventory of dead wood has been carried out since 1994, with information about tree species, decomposition class, position, incline and bark coverage.
An interactive fact sheet with information about dead wood is available through our system TaxWebb.
Why is only data from temporary plots available for download?
There is a wide spectrum of variables and detailed coordinates available for our temporary plots. These are especially relevant in remote sensing applications. Temporary plot data can be accessed here:
We do not reveal coordinates for our permanent plots as this would compromise data integrity. If you wish to discuss a project with us, you are welcome to contact one of our analysts.
How do I get access to data from the permanent plots?
There is a wide spectrum of variables and detailed coordinates available for our temporary plots. These are especially relevant in remote sensing applications. Temporary plot data can be found here:
Data from permanent plots inventoried since 1983 can be ordered but as of now, it is not available for download. Certain restrictions apply for precise coordinates. Anyone can order rough coordinates where plot cluster coordinates has been randomly shifted by 200 to 1,000 metres in any direction.
As far as detailed coordinates for permanent plots are concerned, these are only revealed for researchers through a privacy agreement – reason being it compromises data integrity. Contact one of our analysts for more information.
How do I go about accessing older plot data?
Data from the first inventory (1923–29) is available through our website:
For more information on data from 1923–1952, contact one of our analysts. For more information on 1953 until present time, also contact one of our analysts.
What does it cost to order data from the NFI?
Data and information from the Swedish NFI are free of charge. Many of our services can be accessed directly from our website.
Skogsdata – our annual publication with official statistics
TaxWebb – Our interactive web service where you can customise your own figures and tables
SLU Forest Map – a comprehensive forest map compiled using both inventory data and remote sensing data
We also have a team of analysts with whom you can confer. They can assist you with tailored estimations or data deliveries on a commission basis. We charge a fee to cover the working hours required to compile and perform quality assurance. Contact us to learn more.
Are protected areas included in the NFI inventory? How are they handled in the analyses?
The Swedish NFI has inventoried all protected areas since 2003. To ensure that long time series are comparable within, for example, productive forest land, we delete data within formally protected areas according to the latest map layers from the Swedish Environmental Protection Agency.
Why are NFI statistics published as 5-year averages?
The Swedish NFI is designed to provide reliable estimates for counties with 5 years of inventory data. Given that each year’s field plots are distributed across the country, we are also able to estimate using 1 or 3 years of data for large geographical areas when topicality is emphasized, or estimates with more than 5 years of data for areas smaller than counties; for example forest-rich municipalities or groups of municipalities.
For certain general variables, acceptable annual estimates are produced on a national level.
How do I cite the Swedish NFI?
A good reference to the Swedish NFI can look like this:
J Fridman, S Holm, M Nilsson, P Nilsson, A H Ringvall, G Stahl (2014) Adapting National Forest Inventories to changing requirements - the case of the Swedish National Forest Inventory at the turn of the 20th century Silva Fennica 48: 3. 1095-article. http://www.silvafennica.fi/article/1095
More details on how to quote statistics and data from the Swedish NFI can be found here.
Why does TaxWebb only show data from 1983?
TaxWebb is our interactive analytics system. Currently, the database from which TaxWebb draws its data only contains data from 1983 and onward. We are working on transferring older data (mainly from 1953–1982) to our database and we hope that TaxWebb will provide longer time series in the future.
Why can’t I get a ”per hectare” value for forest from the first inventory (1923-1929)?
The first inventory was a belt inventory with continuous measurements along a 10-metre-wide belt. Different kinds of land use was registered and stand characteristics were described for each forest stand, while counted trees were registered for every 2 km section. Based on this information we cannot say for certain what percentage of the standing volume was on productive forest land and what fell within other land use classes.
How do I know what is and isn’t an official statistic?
The Swedish NFI is responsible for official statistics on the state and change of Swedish forests. The Swedish NFI also publishes a number of statistics-based products not part of the official statistics. All of our products marked with the following logo are official statistics:
I have an idea for a research project – who do I contact?
Don’t hesitate to contact one of our analysts. We are happy to help you develop your research project.
Where can I find examples of articles based on Swedish NFI data?
On our website you will find a list of articles and reports using data from the Swedish NFI:
The list contains publications that we are aware of. If you have an article you think should be included, contact us and we’ll be happy to add it.
How has the design of the NFI changed? Is everything comparable?
The Swedish NFI has undergone many changes during its 100-year history and this makes long-term analyses complicated. Many common variables such as standing volume distributed across tree species, stand age, land cover och dead/living wood are, however, comparable over the entire time series.
Contact one of our analysts to discuss which variables might be useful in your work.