The National Forest Inventory


Next update

Not yet determined

Key figures


million cubic metres growing stock in Norwegian forests

Growing stock and annual increment. Volume inside bark
1 000 cubic meterShareChange, per centChange, per cent
2018 - 20192010 - 2019
Growing stock
Total978 4781000.416.2
Spruce428 329440.115.8
Pine301 858310.713.7
Broad-leaved248 291250.619.8
Annual increment
Total24 186100-2.9-1.7
Spruce12 84553-3.7-0.5
Pine5 45123-2.2-5.7
Broad-leaved5 89024-1.9-0.4

See selected tables from this statistics

Table 1 
Growing stock inside bark and annual increment inside bark. 1 000 m³

Growing stock inside bark and annual increment inside bark. 1 000 m³
Growing stockAnnual increment
1993609 399279 968197 904131 52621 33711 0705 4984 769
1998651 688292 018218 305141 36421 94511 2195 8554 871
1999685 682304 081229 874151 72723 07611 6846 1635 229
2000697 998308 614233 949155 43623 48811 8586 2735 357
2002685 885306 527228 492150 86623 19712 1355 9525 109
2003704 487313 979235 030155 47823 99712 6276 0645 306
2004720 789323 213238 137159 43925 54013 7096 1515 680
2005735 610331 236241 730162 64425 67413 8686 0925 714
2006747 945336 201244 622167 12225 52613 7466 0105 769
2007764 952343 720249 201172 03125 26213 6445 9445 674
2008783 982352 558254 554176 87024 89713 4825 8575 559
2009822 569360 501260 521201 54724 83912 9695 7486 122
2010842 419369 747265 439207 23324 60612 9085 7835 915
2007-2011877 731379 823273 905224 00324 94213 0305 9785 935
2008-2012894 133387 844278 516227 77325 27413 2616 0715 942
2009-2013911 712396 891282 790232 03125 59813 5296 1175 952
2010-2014929 393407 100286 490235 80425 91113 8216 1155 975
2011-2015941 659412 984289 685238 98926 12013 9286 0986 095
2012-2016952 103417 955292 031242 11725 81913 7475 9206 152
2013-2017964 915424 433296 255244 22925 42113 6355 7196 068
2014-2018974 453427 798299 754246 90124 90613 3325 5726 003
2015-2019978 479428 329301 858248 29024 18612 8455 4505 889

Table 2 
Total area surveyed, by type of vegetation and regions. Km²

Total area surveyed, by type of vegetation and regions. Km²
2015-2019TotalProductive forest land1Unproductive forestBroadleaved bogs and pine bogsSedge and peat bogsOther area2
1Areas abrove the coniferous forest line are also included
2Including freshwater
Appraised regions, total323 78282 78248 0729 05713 718170 153
Østfold, Akershus, Oslo and Hedmark37 03219 4912 8311 5221 37011 818
Oppland, Buskerud and Vestfold42 25315 1234 4058681 78920 068
Telemark, Aust-Agder and Vest-Agder31 72911 9316 1737561 12611 743
Rogaland, Hordaland, Sogn og Fjordane and Møre og Romsdal57 74010 4537 6987841 36937 436
Trøndelag41 82310 9446 9572 3353 82417 763
Nordland and Troms64 59011 2749 3521 2261 90140 837
Finnmark48 6163 56710 6561 5662 33930 488

Table 3 
Productive forest area, by development class. 1 000 hectares and per cent

Productive forest area, by development class. 1 000 hectares and per cent1
1 000 hectares
TotalDevelopment class IDevelopment class IIDevelopment class IIIDevelopment class IVDevelopment class V
1Refer to the counties Østfold, Akershus, Oslo, Hedmark, Oppland, Buskerud og Vestfold.These are the only counties that are included in all the inventory cycles presented. As from the inventory cycle 2006-2010, areas above the coniferous forest line are also included.
2002-20063 368948027426731 056
2003-20073 378937937416791 072
2004-20083 391917897486791 084
2005-20093 519957847597301 151
2006-20103 513927797627141 166
2007-20113 510777677837021 180
2008-20123 507747627877111 174
2009-20133 500697457857141 187
2010-20143 499597407867181 196
2011-20153 483617257867181 193
2012-20163 488667117897181 203
2013-20173 483706877927331 201
2014-20183 473706857807371 202
2015-20193 461806737747391 195
Per cent

Table 4 
Growing stock, by type of land, tree species and regions. 1 000 m³ under bark

Growing stock, by type of land, tree species and regions. 1 000 m³ under bark
2015-2019TotalProductive forest landOther type of land
Total978 479866 131401 815256 287208 028112 34826 51445 57140 262
Østfold, Akershus, Oslo and Hedmark255 945238 888122 87185 02330 99417 0575 3037 4874 266
Oppland, Buskerud and Vestfold192 856173 71695 88145 73132 10419 1408 2985 1365 706
Telemark, Aust-Agder and Vest-Agder177 958154 89658 94361 02934 92323 0625 11112 8265 124
Rogaland, Hordaland, Sogn og Fjordane and Møre og Romsdal139 200121 65638 81739 29043 54917 5449367 7598 850
Trøndelag121 404103 68864 42717 51221 74917 7165 0848 2814 352
Nordland and Troms75 43063 61720 8755 42537 31711 8131 7822 6267 405
Finnmark15 6859 67002 2777 3936 01501 4564 559

Table 5 
Annual increment under bark , by type of land, tree species and surveyed regions. 1 000 m3

Annual increment under bark , by type of land, tree species and surveyed regions. 1 000 m3
TotalProductive forest areaOther type of land
Total24 18622 10512 3564 7564 9922 081489694897
Østfold, Akershus, Oslo and Hedmark6 7596 4703 7991 8358362899110889
Oppland, Buskerud and Vestfold4 8194 4802 77581489133915277110
Telemark, Aust-Agder and Vest-Agder4 0543 6351 7611 118756419101210108
Rogaland, Hordaland, Sogn og Fjordane and Møre og Romsdal3 3122 9221 3915201 01239032112246
Trøndelag3 0872 8001 8612946452877911890
Nordland and Troms1 8491 6137691147302363441161

Table 6 
Registered incidence of different habitats in productive forest, by region. Per cent

Registered incidence of different habitats in productive forest, by region. Per cent1
2015-2019Productive forest area below the coniferous forest lineStanding dead treesDead wood lyingTrees with nutrient-rich barkTrees with pendant lichensLate succsessions of deciduousOld treesRich ground vegetation
1Corresponds to the registration of habitats for vulnerable and endangered species (red listed species) in ordinaryforest management planning. Two of more habitats may be registered within the same area.
Østfold, Akershus, Oslo and Hedmark100.
Oppland, Buskerud and Vestfold100.02.718.
Telemark, Aust-Agder and Vest-Agder100.03.721.
Rogaland, Hordaland, Sogn og Fjordane and Møre og Romsdal100.
Nordland, Troms and Finnmark100.02.820.

About the statistics

The statistics provide information on the condition and development of Norway’s forest resources. They give figures on growing stock, annual increments, forest area, age distribution, type of land and tree species.


Definitions of the main concepts and variables

Growing stock

Total volume of the standing forest under bark. Comprises trees with a diamter of at least 5 cm at breast height (1.3 metre above ground level).

Annual increment, forest

Annual gross increment in volume in standing forest inside bark.

Development class

Describes the forest's development class from non- regenerated forest to old forest.

Site quality

An expression of the area's capacity to produce wood when stocked with a tree species suitable for the local growing conditions. The site quality of the H40-system is based upon the top height (the average height of the hundred trees per hectare with the largest diameter) of the trees at the age of 40 years at breast height (1.3 m above ground level).

Standard classifications

Classification of productive forest area by development class

Classification of productive forest area by site quality (H40)

Administrative information

Name and topic

Name: The National Forest Inventory
Topic: Agriculture, forestry, hunting and fishing

Responsible division

Division for Housing, Property, Spatial and Agricultural Statistics

Regional level

The results are mainly published at region level.

Frequency and timeliness

The results are published yearly. The National Forest Inventory has an inventory cycle of five years. From 1994 the assessment is running. A new result based on the registrations from the last 5 years can always be estimated for the regions and for the country

International reporting

International reporting of results from The National Forest Inventory are reported by the The Norwegian Institute of Bioeconomy Reasearch.


Microdata are stored by The National Forest Inventory.


Background and purpose

The National Forest Inventory is a sample plot inventory aimed at providing data on natural resources and the environment for forest land in Norway. The Inventory is conducted by the Norwegian Forest and Landscape Institute. Inventory work was started in 1919, with the different inventory cycles taking place in the following years:

1: 1919-30 2: 1937-56 3: 1957-64 4: 1964-76 5: 1980-86 6: 1986-93 7: 1994-98 8: 2000-04 9: 2005-09

The entire country (except Finnmark county) was surveyed during the most recent period. Each inventory cycle covers the most important forest districts, while inventories in western and northern Norway have been carried out less frequently and are sometimes incomplete.

Users and applications

The most central users of the results from the National Forest Inventory are public administration at national and county level. The results serve as important input for the formation of forestry policies and control the effects of it.

In recent years, the demand for national forestry statistics has increased, and the National Forest Inventory is a central data source. Data from the inventories are used for example in research to develop descriptive models of forest dynamics.

The forest industry is an important user of the data. Among others thing, they need the data for strategic planning in the sawmill and pulp industry. The data are also used by educational institutions and by professionals in agriculture, forestry and environmental protection.

Equal treatment of users

No external users have access to the statistics and analyses before they are published and accessible simultaneously for all users on at 8 am. Prior to this, a minimum of three months' advance notice is given inthe Statistics Release Calendar. Read more about principles for equal treatement of all users on

Coherence with other statistics

Statistics Norway has estimated the productive forest area in The Sample Surveys of Agriculture and Forestry 2004 and 2008, The Census of Agriculture and Forestry 1979 and 1989. The Farm Register of the Norwegian Agricultural Authority also contains information about productive forest area at property level. Total productive forest area based on the Farm Register is published in the annual structural statsitics of forestry.

Legal authority

Not relevant

EEA reference

Not relevant



The statistics include all counties except Finnmark, however Finnmark will also be surveyed during the present five-year cycle. As from the inventory cycle 2005-2009, areas above the coniferous forest line are also included. Protected or other closed-off areas of productive forest are not included.

The figures are published annually.

Data sources and sampling

The only data source is the National Forest Inventory's database. One of the main tasks of the National Forest Inventory is the assessment of timber resources. Data are collected so that the volume can be computed for different tree species, diameters and quality classes. Numbers of trees and annual increments are also calculated.

The National Forest Inventory's data collection is based on data from permanent sample plots. For the entire country except Finnmark, a systematic sample plot inventory in a bond by 3 x 3 kilometres is established. In the present inventory cycle, sample plots for Finnmark are also established. The plots are visited every five years and the survey forms the basis for statistics for the whole of Norway. In order to publish data by county, temporary plots are established in the counties when each county is appraised. Each county is appraised every fifteen years. An extensive number of attributes concerning forest conditions are recorded on the plots, some of which describe the area. Parameters that characterise level of development and species composition of the vegetation, certain aspects of biodiversity, utilisation and yield capacity of the land, forest treatment, conditions surrounding forest operations, etc., are measured or estimated. Inside a 250 square metre circle, every tree with a diameter of more than five centimetres in breast height (1.3 metres above ground level) is callipered.

The sampling design has changed considerably over the years. The first two cycles were carried out as strip sampling inventories. A system of parallel strips was established throughout the area of interest, and measurements were taken within these strips. In the middle of the 1950s, the strip sampling was replaced by a systematic sample plot inventory, a method which has also been used subsequently. However, minor alterations concerning sampling design have been made several times.

An important difference between the period 1986-1993 and the previous inventory cycles was the introduction of permanent sample plots. A sub-sample of the established plots was marked in order to be able to re-measure the exact same area in future inventories. This was to provide greater possibilities for detecting changes in forest conditions. The permanent plots were re-measured during the period 1994-1998, according to a specific pattern. The inventory of one single year will provide representative results for the whole country.

Collection of data, editing and estimations

Highly conspicuous markings are avoided in order to prevent the location of the plots from being too obvious to passers-by. The permanent plots should represent a random sample of the forests in Norway, and should not be treated any different than the rest of the forests. A total of approximately 16 000 permanent sample plots have been established, of which about 10 500 are located on productive forest and other wooded land below the coniferous forest limit. On average, the sampled area comprises about 3 x 10 -5 of the surveyable area.

Before each field season, training is held for the field crew. During the field season, the office staff visit the field workers at least once and some controls are carried out. In most cases, a control of the assessment is done. About 5 per cent of the sample plots are surveyed once more.

Corrections of the field instructions are made before every field season. A main revision is carried out every five years.

In order to estimate figures, for instance for a county, the area factor must be known. In a 3 x 3 kilometre net the area factor will be close to nine square kilometres or 900 hectares. Each sample plot will represent 900 hectares. For each tree measured, a volume with and without bark and the increment are estimated. Multiplying this with the area factor will establish how much each tree represents in this area. The volume for the growing stock in a county for instance can be found by summarising the volume of each measured tree in the county multiplied with the area factor.

Seasonal adjustment

Not relevant


Figures on property level are not published.

Comparability over time and space

The National Forest Inventory carried out the first assessment at county level in 1919.

Accuracy and reliability

Sources of error and uncertainty

Systematic errors are caused by errors or uncertainties in measurement, estimation and recording in the field, which are one-sided. Efforts are being made to reduce these errors as far as possible by training the field crews and checking their measurements. An example of errors of this type is the possibility of apparent area changes for productive forest land, which are really caused by different methods of judging the coniferous forest limit. The magnitude of systematic errors cannot normally be calculated.

Random errors of the results are caused by the limited sample of the forest area and wood resources measured by the inventory, in addition to random errors of measurement. A measure for the random error is the so-called standard error, which is possible to calculate. The root mean square error (RMS error) depends on the number of sample plots and the variance of the parameter of interest, for instance volume of growing stock. If the observations are divided into more groups, the magnitude of the RMS error will be higher within each group.


Not relevant