Articles by Juha-Pekka Hotanen

Fresh and herb-rich upland forest sites in the north-western part of the central boreal vegetation zone in Finland were studied with respect to vegetation structure and vegetation-environment relationships (soil, stand characteristics). Two fresh heath vegetation data sets, one from the northern boreal zone and the other from the central boreal zone, were compared with the data of this study using multivariate methods.

The variation in heath forest vegetation within the climatically uniform area was mainly determined by the fertility of the soil (primarily Ca and Mg) and the stage of stand development. N, P and K content of the humus layer varied little between the vegetation classes. Fertile site types occurred, in general, on coarse-textured soils than infertile site types, may be due to the fact that the sample plots were located in various bedrock and glacial till areas, i.e. to sampling effects.

The place of the vegetational units of the study area in the Finnish forest site type system is discussed. The vegetation of the area has features in common with the northern boreal zone as well as the southern part of the central boreal vegetation zone. The results lend some support to the occurrence of a northern Myrtillus type or at least that intermediate form of fresh and herb-rich mineral soil sites commonly occur in the studied area. It is argued that the older name Dryopteris-Myrtillus type is more suitable than Geranium-Oxalis-Myrtillus type for herb-rich heath sites in the study area.

• Lehtelä, E-mail: ml@mm.unknown
• Hotanen, E-mail: jh@mm.unknown
• Sepponen, E-mail: ps@mm.unknown

In 2019–2023 the 13th Finnish National Forest Inventory (NFI) was implemented by measuring a total of 62 266 sample plots across the country. The methodology of the sampling and measurements was similar as in the previous inventory, but the proportion and number of remeasured permanent plots was increased to improve the monitoring of annual increment and other changes in the forests. Only 6.2 M ha (14%) of Finland’s total land area (30.4 M ha) is other land than forestry land. Productive and poorly productive forests cover 22.9 M ha (75%) of the total land area.  The forest area has remained stable in recent decades but the forest area available for wood supply (FAWS) has decreased due to increased forest protection – 23% of the forestry land and 10% of the productive forest are not available for wood supply. Compared to the previous inventory, forest resources have continued to increase but the average annual increment has declined from 107.8 M m³ to 103.0 M m³. The quality of forests from the timber production point of view has remained relatively good or improved slightly. The area of observed forest damage on FAWS is 8.4 M ha (46% of FAWS area), half of these minor damages with no impact on stand quality. Although the area of forest damage has not increased, the amount of mortality has continued to increase, and is now 8.8 M m³ year^–1. The amount of dead wood has continued to increase in South Finland, while in North Finland the declining trend has turned into a slight increase. Since the 1920s, the area of forestry land has remained stable, but the area of productive forest has increased due to the drainage of poorly productive or treeless peatlands. The total volume of growing stock has increased by 84% and annual increment has more than doubled.

• Korhonen, Natural Resources Institute Finland (Luke), P.O.Box 68, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-6198-853X E-mail: kari.t.korhonen@luke.fi
• Räty, Natural Resources Institute Finland (Luke), P.O.Box 2, FI-00790, Helsinki, Finland https://orcid.org/0000-0001-9898-8712 E-mail: minna.raty@luke.fi
• Haakana, Natural Resources Institute Finland (Luke), P.O.Box 2, FI-00790, Helsinki, Finland E-mail: helena.haakana@luke.fi
• Heikkinen, Natural Resources Institute Finland (Luke), P.O.Box 2, FI-00790, Helsinki, Finland https://orcid.org/0000-0003-3527-774X E-mail: juha.heikkinen@luke.fi
• Hotanen, Natural Resources Institute Finland (Luke), P.O.Box 68, FI-80100 Joensuu, Finland E-mail: juha-pekka.hotanen@luke.fi
• Kuronen, Natural Resources Institute Finland (Luke), P.O.Box 2, FI-00790, Helsinki, Finland https://orcid.org/0000-0002-8089-7895 E-mail: mikko.kuronen@luke.fi
• Pitkänen, Natural Resources Institute Finland (Luke), P.O.Box 68, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-7583-6297 E-mail: juho.pitkanen@luke.fi

We describe the methodology applied in the 12th national forest inventory of Finland (NFI12) and describe the state of Finland’s forests as well as the development of some key parameters since 1920s. According to the NFI12, the area of forestry land (consisting of productive and poorly productive forest, unproductive land, and other forestry land) is 26.2 M ha. The area of forestry land has decreased from 1920s to 1960s due to expansion of agriculture and built-up land. 20% of the forestry land is not available for wood supply and 13% is only partly available for wood supply. The area of peatlands is 8.8 M ha, which is one third of the forestry land. 53% of the current area of peatlands is drained. The volume of growing stock, 2500 M m³, is 1.7 times the volume estimated in NFI1 in the 1920s for the current territory of Finland. The estimated annual volume increment is 107.8 M m³. The increment estimate has doubled since the estimate of NFI2 implemented in late 1930s. The annual mortality is estimated to 7 M m³, which is 0.5 M m³ more than according to the previous inventory. Serious or complete damage was observed on 2% of the productive forest available for wood supply. The amount of dead wood is on average 5.8 m³ ha^–1 in productive forests. Since the NFI9 (1996–2003) the amount of dead wood has increased in South Finland and decreased in North Finland both in protected forests and forests available for wood supply (FAWS). The area of natural or almost natural forests on productive forest is 380 000 ha, out of this, 42 000 ha are in FAWS and 340 000 ha in protected forests.

• Korhonen, Natural Resources Institute Finland (Luke), P.O. Box 68, FI-80100 Joensuu, Finland E-mail: kari.t.korhonen@luke.fi
• Ahola, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: arto.ahola@luke.fi
• Heikkinen, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: juha.heikkinen@luke.fi
• Henttonen, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: helena.henttonen@luke.fi
• Hotanen, Natural Resources Institute Finland (Luke), P.O. Box 68, FI-80100 Joensuu, Finland E-mail: juha-pekka.hotanen@luke.fi
• Ihalainen, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: anttivj.ihalainen@elisanet.fi
• Melin, Natural Resources Institute Finland (Luke), P.O. Box 68, FI-80100 Joensuu, Finland E-mail: markus.melin@luke.fi
• Pitkänen, Natural Resources Institute Finland (Luke), P.O. Box 68, FI-80100 Joensuu, Finland E-mail: juho.pitkanen@luke.fi
• Räty, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: minna.raty@luke.fi
• Sirviö, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: maria.sirvio@uudenmaanliitto.fi
• Strandström, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00790, Helsinki, Finland E-mail: mikael.strandstrom@luke.fi

• Turtiainen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: marjut.turtiainen@uef.fi
• Miina, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jari.miina@metla.fi
• Salo, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: kauko.salo@metla.fi
• Hotanen, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: juha-pekka.hotanen@metla.fi

• Miina, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jari.miina@metla.fi
• Hotanen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jph@nn.fi
• Salo, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: ks@nn.fi

• Hotanen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: juha-pekka.hotanen@metla.fi
• Maltamo, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: mm@nn.fi
• Reinikainen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ar@nn.fi

• Hotanen, Finnish Forest Research Institute, Joensuu Research Centre, P.O.Box 68, FIN-80101 Joensuu, Finland E-mail: juha-pekka.hotanen@metla.fi

The coverage of bilberry (Vaccinium myrtillus L.) was modelled as a function of site and stand characteristics using the permanent sample plots of the National Forest Inventory (NFI) (Model 1). The sample sites consisted of mineral soil forests as well as fells and peatland sites. Annual variation in the bilberry yield (Model 2) was analysed based on measurements over 2001–2014 in the permanent sample plots (so-called MASI plots) in various areas of Finland. We derived annual bilberry yield indices from the year effects of Model 2 and investigated whether these indices could be used to estimate annual variation in bilberry crops in Finland. The highest bilberry coverage was found in mesic heath forests and fell forests. On peatlands the coverage was, on average, lower than on mineral soil sites; the peatland sites with most bilberry coverage were meso-oligotrophic and oligotrophic spruce mires and oligotrophic pine mires. Our bilberry yield indices showed similar variation to those derived from the mean annual berry yields reported and calculated earlier using the MASI plots; the correlation between the indices was 0.795. This approach to calculating annual berry yield indices is a promising way for estimating total annual bilberry yields over a given period of time. Models 1 and 2 can be used in conjunction with the Miina et al.’s (2009) bilberry yield model when bilberry coverage, average annual yield and annual variation in the yield are to be predicted in forest planning.

• Turtiainen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: marjut.turtiainen@uef.fi
• Miina, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Box 68, FI-80101 Joensuu, Finland E-mail: jari.miina@luke.fi
• Salo, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, Box 68, FI-80101 Joensuu, Finland E-mail: kauko.salo@luke.fi
• Hotanen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Box 68, FI-80101 Joensuu, Finland E-mail: juha-pekka.hotanen@luke.fi