File README-2021.txt (UTF-8) 12.4.2023 MULTI-SOURCE NATIONAL FOREST INVENTORY (MS-NFI) RASTER MAPS OF 2021 =================================================================== 1. Terms of Use --------------- The Natural Resources Institute Finland (Luke) owns the copyright, data protection, and other immaterial rights to this product. The Topographic Database from the National Land Survey has been utilized when making the product. This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA. When using the material, the owner of the rights to the material must be given as "©Natural Resources Institute Finland, 2021" and the name of the material must be given as "The Multi-source National Forest Inventory Raster Maps of 2021". The description of the method is in the references at the end of this file. A scientific citation practice shall be used in research use. 2. The Files ------------ The raster maps include 45 themes (described later). For delivery, each theme is divided into subsets according to the Finnish TM35 division of maps from the National Land Survey (URL https://www.nls.fi/). For simplicity, the sheets K2 and L2 (Ahvenanmaa) are combined as well as the sheets V3 and W3 (Lapland). The raster files are in GEOTIFF format. The map coordinate system is ETRS-TM35FIN. The pixel size in the map coordinate system is 16 m by 16 m. The results are in 16-bit numbers (the exception is the index map, mista_*, that is in 8-bit numbers). The unit of each theme is given later. The numbers 32766 and 32767 have been reserved for the following purposes: 32766 pixel where result should have been computed but it was not possible because of, e.g., clouds 32767 pixel that is outside forest land, poorly productive land, or unproductive land, or is not in Finland 3. Contact and more information ------------------------------- More information about the Finnish multi-source national forest inventory is given at http://urn.fi/URN:ISBN:978-952-380-538-5 The queries about the products are asked to be sent to the email address mvmi@luke.fi. 4. The Material --------------- 4.1 General information The Finnish Forest Research Institute (Metla) developed a method called multi-source national forest inventory (MS-NFI). The first operative results were calculated in 1990. Small area forest resource estimates, in here municipality level estimates, and estimates of variables in map form are calculated using field data from the Finnish national forest inventory, satellite images and other digital georeferenced data, such as topographic database of the National Land Survey of Finland. Eleven sets of estimates have been produced for the most part of the country until now and ten sets for Lapland. The number of the map form themes in the most recent version, from year 2021, is 45. In addition to the volumes by tree species and timber assortments, the biomass by tree species groups and tree compartments have been estimated. The first country level estimates correspond to years 1990-1994. The most recent versions are from years 2005, 2007, 2009, 2011, 2013, 2015, 2017, 2019 and 2021. The maps from 2021 is the seventh set of products freely available. The MTT Agrifood Research Finland, the Finnish Forest Research Institute, the Finnish Game and Fisheries Research Institute (RKTL) and the Information Centre of the Ministry of Agriculture and Forestry Tike merged in 2015 to create the Natural Resources Institute of Finland (Luke). The MS-NFI results from 2013 were the first published by Luke. A new set of the products will be produced annually or biannually in the future. The maps are in raster format in ETRS-TM35FIN coordinate system. Until 2011, the pixel size was 20mx20m. In 2013 the pixel size was changed to 16mx16m. The products cover the combined land categories forest land, poorly productive forest land and unproductive land. The other land categories, as well as water bodies, have been delineated out using the elements of topographic database of the Land Survey of Finland. This classification is independent of the estimated themes. 4.2 Construction of the theme maps For the 2021 products, in total 51 833 NFI field plots were used, locating either on forest land, poorly productive forest land or unproductive land. The satellite images used included 7 Sentinel-2A MSI images, 6 Sentinel-2B MSI images and 6 (3 orbits) Landsat 8 OLI images. The images were from 2021. The field data in the 2021 products were up-dated to correspond the situation on 31 July, 2021. The length of the up-dating period was calculated for each field plot from the date of the field measurement to the up-dating date 31 July, 2021. The start of the tree growth was supposed to be on May 1. The relative increment of the volume of the growing stock in a forest stand was calculated using the models by Nyyssönen and Mielikäinen (1978) for pine (Pinus silvestris) and spruce (Picea abies). The models for pine were used for broad-leaved trees. The volume increments were calculated by stand layers in case of multi-layer stands. The proportions of volumes by layers were estimated proportionally to the quantity the basal area of the layer multiplied by the mean height of the layer. Regeneration cuttings on the field plots were assessed using satellite images and, in some cases, with aerial photographs. The stand data of the plots cut were changed to stand data for open area plots. The final volume increments were calibrated in such a way that the volumes by tree species on July 31, 2021, was the same as that given by the regression line estimated from field data alone when the results seemed reasonable. Otherwise the target was determined heuristically. For the relative height increment, diameter increment and basal area increment, simple fixed parameter regression models were estimated using data from the permanent sample plots of NFI10. The models were used in a similar way as the volume models. The biomass estimates by field plots and biomass compartments were up-dated proportionally to the volume changes. For a cover as complete as possible from the entire country, the 2021 product has been completed by the data estimates from the recent years. The product thus consists of the following sub-products: 1. The estimates from 2021, based on the NFI field data from 2017-2021 updated to 31.7.2021 and the satellite images from 2021 (99.45 % of forest pixels), 2. The estimates from 2019, based on the NFI field data from 2015-2019 updated to 31.7.2019 and the satellite images from 2018-2019 (0.52 % of forest pixels), 3. The estimates from 2019, based on the NFI field data from 2013-2017 updated to 31.7.2017 and the satellite images from 2017-2018 (0.02 % of forest pixels), 4. The estimates from 2015, based on the NFI field data from 2012-2016 updated to 31.7.2015 and the satellite images from 2015-2016 (0.002 % of forest pixels), 5. The estimates from 2013, based on the NFI field data from 2009-2013 updated to 31.7.2013 and the satellite images from 2012-2014 (0.0005 % of forest pixels). Data source index, MS-NFI-2021, has been added to the product to indicate the source of the estimates. The pixel values in the index image correspond to the numbering of the previous list. The value is zero for those pixels where no applicable estimate was found. The map form estimates were made using the improved k-Nearest Neighbour method (ik-NN method). The value of five for k was used most frequently. The weights of the features in the ik-NN method are sought using an optimization method based on genetic algorithm. Coarse scale estimates of forest variables were used as the supplementary data. The volumes by tree species groups were selected as the variables. The purpose is to direct the selection of the neighbours, on the average, to forests similar to the target pixel (see the references below). The estimation was made separately for mineral soils, mires and open bogs and fens. The stratification of both the satellite image and the field plots were made using the topographic map data of Land Survey Finland. 4.3 The themes The product consists of 44 theme maps in raster format plus data source index. The themes can be grouped as follows: The volume of growing stock is available as a total for all tree species and broken down into tree species groups (Scots pine, Norway spruce, Birch, Other broad-leaved trees) and into timber assortments (saw timber, pulpwood). The volume of a tree is defined as the volume of the stem wood above stump until the top of the tree. The volume of a tree in the field data is estimated using the parameters measured in the field and the volume models. The unit and class interval of the volume is 1 m3/ha in the products available for downloading. The biomass of the growing stock has been estimated and is available by tree species groups and by seven tree compartments. The biomass of stem and bark of a tree is defined as the biomass of the stem above bark and above stump until the top of the tree. The biomass of the living branches includes the biomass of the living branches without needles or leaves. The biomass of the dead branches includes the biomass of the dead branches possibly left in a living tree. The foliage biomass includes the biomass of the living needles or leaves. The biomass of stumps includes the biomass of the above and below ground stump parts without roots. The root biomass includes the biomass of the living roots with a diameter of at least 1 cm. The biomass of stem residual is defined as that part of the stem biomass that can not be used as timber or pulpwood due it size or quality. The biomasses of the sample trees on a NFI field plot are calculated from the living sample trees belonging to a plot using the wood density models (Repola et al. 2007) and biomass models (Repola 2008, 2009). The biomasses of the trees called tally trees are estimated using the estimates of the sample trees (with more parameters measured) and the parameters of tally trees and stands. The unit of the biomass in the maps available for downloading is 10 kg/ha. The basal area of the growing stock on a forest stand is the cross section area of the tree stems of a stand per hectare and measured at a height of 1.3 m. The basal area is measured in the field for the field plot stands on forest land and poorly productive forest land in the classes of 1 m2/ha. The age of the growing stock on a forest stand is the weighted average of the trees, the basal area of the tree as the weight. The age is assessed in the field for the field plot stands on forest land and poorly productive forest land in the classes of one year. The mean height of the trees on a forest stand is the height of the basal area median tree for the development classes young thinning stand or more mature stands. It is about the same as the basal area weighted average height. For seedling stands, the mean height is the average height of the dominant and co-dominant seedlings. The mean height is assessed in the field in the classes of 1 dm. The mean diameter of trees is assessed at a height of 1.3 metres and is the the diameter of the basal area median tree. It is about the same as the weighted average diameter, the basal area of a tree as the weight. It is assessed for the field plot stands on forest land and poorly productive forest land in the classes of 1 cm. The canopy cover of trees is the vertical projection area on the horizontal plane of the canopies of the individual trees on a field plot (without double counting the overlapping canopies). In NFI10, it was assessed in the field as a shares (0-99%) on a fixed radius plot. For the NFI11 plots, it was estimated using k-NN method and the NFI10 plot data. In North Lapland in NFI9, the canopy cover was assessed in three categories if the plot was either on forest land, poorly productive forest land or unproductive land. A regression model was constructed to estimate the cover in the classes of one percent. The canopy cover proportion of broad-leaved trees is derived from the total cover using the basal area. However, in the seedling stands, the canopy cover of broad-leaved trees is assessed using the shares of the stem numbers. The theme "Land class" divides forestry land into three sub-categories, forest land (pixel value 1), poorly productive forest land (2), unproductive land (3). The theme "Land Class based on FAO FRA" divides forest into four sub-categories forest (pixel value 1), other wooded land (2), other land (3) and other land with tree cover (4), based on the definition of the United Nations FAO Global Forest Resource Assessment (FRA). The theme "Site main class" divides forest land, poorly productive forest land and unproductive land into mineral soil (pixel value 1) and peatland site classes. The peatland site class is sub-divided into three categories spruce mires (2), pine mires (3) and treeless peatland (4, open bogs and fens). A site is classified as peatland if the organic layer is peat, or if more than 75% of the ground vegetation is peatland vegetation. Otherwise, the site is mineral soil. Both the field plots and satellite images are stratified prior the analyses into three strata, 1) mineral soil, 2) pine and spruce mires, 3) treeless peatland using the topographic map data. Thus in the products, each NFI field data based category can occur within each map based stratum. The site fertility classes are used for grouping the forest by vegetation zones into uniform classes according to their site fertility and wood production capacity. In national land-use classification, all stands on mineral soil with site fertility class in 1 - 6 were classified as forest land (1 is herb rich sites, 2 is herb rich heath forests, 3 is mesic forests, 4 is sub-xeric forests, 5 is xeric forests, 6 is barren forests). Class 7 (rocky and sandy soils and alluvial lands) can be forest land, poorly productive forest land, or unproductive land, and class 8 (summit and fjeld land with single coniferous trees) either poorly productive forest land or unproductive land. Classes 9 (mountain birch dominated fjelds) and 10 (Open fjelds) are poorly productive forest land or unproductive land. Both natural and drained peatlands are classified into six site fertility classes independently of the land class. Class 1 includes euthropic mines and fens, 2 mesothropic mires and fens, 3 meso-oligothropic mires, 4 oligothropic mires, 5 oligo-ombothropic mires and 6 Sphagnum fuscum dominated mires. Both the field plots and satellite images are stratified prior the analyses into three strata, mineral soil, pine mires and spruce mires, treeless peatland . The site fertility class is estimated for each pixel as the most likely site fertility class. Thus in the products, each NFI field data based category can occur within each map based stratum. 4.4 The accuracy of the estimates The estimation errors at pixel level are rather high but decrease when the area in question increases, i.e., when the area of interest consists of several pixels. The errors vary by the themes and depend also on the actual value in the field, for example on the volume of growing stock and the site fertility class. The following error estimates are based on the MS-NFI 2019 product. The magnitude of the average errors of the volume estimates at pixel level are presented below (SF = South Finland, NF = North Finland, min = mineral soil, peat = peatland, m3/ha): species group assort. SF/min SF/peat NF/min NF/peat all all 87 67 50 39 pine all 67 51 44 30 pine saw t. 44 31 24 12 pine pulpw. 39 32 32 24 spruce all 64 43 28 19 spruce saw t. 47 30 16 10 spruce pulpw. 30 22 17 13 birch all 35 32 18 19 birch saw t. 11 7 2 2 birch pulpw. 27 26 15 17 other br. l. all 25 16 9 6 other br. l. saw t. 8 5 1 1 other br. l. pulpw. 18 11 7 5 The magnitude of the average error of the biomass estimates at pixel level are presented below (SF = South Finland, NF = North Finland, min = mineral soil, peat = peatland, 10 kg/ha): tree species compartment SF/min SF/peat NF/min NF/peat pine stem and bark 2624 1982 1711 1179 pine living branches 355 280 315 215 pine dead branches 91 74 70 51 pine foliage 118 98 108 81 pine stump 186 150 141 100 pine roots 609 470 444 295 pine stem residual 153 146 176 135 spruce stem and bark 2342 1596 1074 744 spruce living branches 511 367 319 211 spruce dead branches 95 68 46 34 spruce foliage 324 240 195 142 spruce stump 201 142 115 75 spruce roots 722 529 424 292 spruce stem residual 164 158 103 99 broad-leaved stem and bark 2127 1755 974 994 broad-leaved living branches 350 272 189 181 broad-leaved dead branches 19 16 11 11 broad-leaved foliage 75 70 55 54 broad-leaved stump 190 152 116 111 broad-leaved roots 585 505 340 342 broad-leaved stem residual 386 339 285 274 The magnitude of the average error of the estimates of the other continuous variables at pixel level are presented below (SF = South Finland, NF = North Finland, min = mineral soil, peat = peatland): theme SF/min SF/peat NF/min NF/peat unit age 26 30 47 36 a basal area 7 7 5 5 m2/ha mean height 52 43 38 31 dm mean diameter 7 5 6 4 cm canopy cover 17 17 16 15 % canopy cover of br. l. 15 14 10 11 % The overall accuracy (OA) at pixel level of the land class is on the average 94% when the classification is compared to that based on the NFI field data. The user accuracy (UA) of the category forest land is on average 96% while the producers accuracy (PA) is on average 99%. The corresponding figures on poorly productive forest land are 61% and 52% and on unproductive land 89% and 78%. The pixel level OA of main site class (mineral soil, spruce mire, pine mire, treeless mire) is 85%. For the category mineral soil, UA is 89% and PA 96%. The corresponding figures for spruce mires are 47% and 22%, for pine mires 79% and 78% and for treeless mires 96% and 84%. The assessment of site fertility is very challenging even in the field and the results vary by the assessors (field crew leaders). For site fertility class, OA is 55% as compared to the NFI field data. In most cases, the difference was not more than one class. The differences were most frequent on one hand for the categories herb rich sites and herb rich heath forests and for the corresponding peatland sites, and on the other for poor mineral soil sites and for ombrotrophic peatlands. The accuracies are highest for mesic forest and for the corresponding peatlands (meso-oligotrophic peatlands). In this category, UA is 61% and PA 68% when compared to the result based on the NFI field data. The errors of estimates at areal level are lower than the errors presented above. 4.5 References More information about the methods and the accuracies are given in the publications, e.g.: Tomppo, E., Haakana, M., Katila, M. & Peräsaari, J. 2008. Multi-source national forest inventory - Methods and applications. Managing Forest Ecosystems 18. Springer. 374 p. ISBN 978-1-4020-8712-7. Mäkisara, K., Katila, M. & Peräsaari, J. 2022. The Multi-Source National Forest Inventory of Finland – methods and results 2017 and 2019. Natural resources and bioeconomy studies 90/2022, Natural Resources Institute Finland. 73 s. http://urn.fi/URN:ISBN:978-952-380-538-5 Mäkisara, K., Katila, M. & Peräsaari, J. 2019. The Multi-Source National Forest Inventory of Finland – methods and results 2015. Natural resources and bioeconomy studies 8/2019, Natural Resources Institute Finland. 57 p. https://urn.fi/URN:ISBN:978-952-326-711-4 Tomppo, E. & Halme, M. 2004. Using coarse scale forest variables as ancillary information and weighting of variables in k-NN estimation: a genetic algorithm approach. Remote Sensing of Environment 92: 1-20. 5. The list of the themes and the file names File name Theme maaluokka_ Land class 2021 (1-3) fra_luokka_ Land class based on FAO FRA 2021 (1-4) paatyyppi_ Site main class 2021 (1-4) kasvupaikka_ Site fertility class 2021 (1-10) keskilapimitta_ Stand mean diameter 2021 (cm) keskipituus_ Stand mean height 2021 (dm) ika_ Stand age 2021 (year) ppa_ Stand basal area 2021 (m2/ha) latvuspeitto_ Canopy cover 2021 (%) lehtip_latvuspeitto_ Canopy cover of broad-leaved trees 2021 (%) tilavuus_ Volume, the growing stock 2021 (m3/ha) manty_ Volume, pine 2021 (m3/ha) mantytukki_ Volume, pine saw timber 2021 (m3/ha) mantykuitu_ Volume, pine pulpwood 2021 (m3/ha) kuusi_ Volume, spruce 2021 (m3/ha) kuusitukki_ Volume, spruce saw timber 2021 (m3/ha) kuusikuitu_ Volume, spruce pulpwood 2021 (m3/ha) koivu_ Volume, birch 2021 (m3/ha) koivutukki_ Volume, birch saw timber 2021 (m3/ha) koivukuitu_ Volume, birch pulpwood 2021 (m3/ha) muulp_ Volume, other broad-leaved trees 2021 (m3/ha) muulptukki_ Volume, other broad-leaved trees saw timber 2021 (m3/ha) muulpkuitu_ Volume, other broad-leaved trees pulpwood 2021 (m3/ha) bm_manty_runkokuori_ Biomass, pine, stem and bark 2021 (10 kg/ha) bm_manty_neulaset_ Biomass, pine, foliage 2021 (10 kg/ha) bm_manty_elavatoksat_ Biomass, pine, living branches 2021 (10 kg/ha) bm_manty_kanto_ Biomass, pine, stump 2021 (10 kg/ha) bm_manty_juuret_ Biomass, pine, roots, d > 1 cm 2021 (10 kg/ha) bm_manty_kuolleetoksat_ Biomass, pine, dead branches 2021 (10 kg/ha) bm_manty_latva_ Biomass, pine, stem residual 2021 (10 kg/ha) bm_kuusi_runkokuori_ Biomass, spruce, stem and bark 2021 (10 kg/ha) bm_kuusi_neulaset_ Biomass, spruce, foliage 2021 (10 kg/ha) bm_kuusi_elavatoksat_ Biomass, spruce, living branches 2021 (10 kg/ha) bm_kuusi_kanto_ Biomass, spruce, stump 2021 (10 kg/ha) bm_kuusi_juuret_ Biomass, spruce, roots, d > 1 cm 2021 (10 kg/ha) bm_kuusi_kuolleetoksat_ Biomass, spruce, dead branches 2021 (10 kg/ha) bm_kuusi_latva_ Biomass, spruce, stem residual 2021 (10 kg/ha) bm_lehtip_runkokuori_ Biomass, broad-leaved trees, stem and bark 2021 (10 kg/ha) bm_lehtip_neulaset_ Biomass, broad-leaved trees, foliage 2021 (10 kg/ha) bm_lehtip_elavatoksat_ Biomass, broad-leaved trees, living branches 2021 (10 kg/ha) bm_lehtip_kanto_ Biomass, broad-leaved trees, stump 2021 (10 kg/ha) bm_lehtip_juuret_ Biomass, broad-leaved trees, roots, d > 1 cm 2021 (10 kg/ha) bm_lehtip_kuolleetoksat_ Biomass, broad-leaved trees, dead branches 2021 (10 kg/ha) bm_lehtip_latva_ Biomass, broad-leaved trees, stem residual 2021 (10 kg/ha) mista_ Data source index, MSNFI 2021