The FIRE experiment

FIre and Tree Retention Experiment (FIRE)

FIRE is a long-term and large-scale field experiment to explore the effects fires and forest management on the maintenance and restoration of biodiversity in managed and protected forests.

FIRE on pitkäkestoinen ekologian kenttäkoe, jonka avulla selvitetään metsäpalon (kulotuksen) ja hakkuiden vaikutuksia metsien ekologisiin ominaispiirteisiin ja monimuotoisuuteen. FIRE käynnistettiin vuonna 1999. Hankkeen esittely suomeksi löytyy täältä:

Full description of this project and its background is available here (in Finnish only, pdf).

Tutkimushankkeen esittely suomeksi, Luonnon Tutkija 1-2/2013 (pdf).

FIRE was started in 1999

Photo shows experimental burning of one of the study sites. All the experimentally burned sites were completed in two days at the end of June, 2001, during same seasonal phase and under similar weather conditions.


Based on nationwide assessments (Kouki et al. 2018, Hyvärinen et al. 2019*), over 1600 species living in forests in Finland are threatened, extinct or near threatened and about 75 % of natural forest habitats are threatened*. The reasons for such threats to biodiversity are most often related to intensive forest management practised during recent decades.

Protected areas cover only less than 10 % of the forest land in Finland, and the majority of these areas is located in northern part of the country. It is unlikely that protected areas alone can maintain forest biodiversity.

Consequently, novel ways to manage the production forests are required. The novel management should maintain or restore such forest properties that can alleviate the negative consequences of forest management on the forest biota and ecosystems.

Objectives of the experiment

In 1999 a large scale field experiment was initiated, to resolve key issues on maintaining biodiversity in forests. The focus is on comparisons between disturbances caused by natural disturbances (fire) and by management (timber harvesting).

The aim is to reveal the impacts of tree retention (or harvest intensity) and fire on species occurrence patterns and ecosystem properties. The main purpose is to analyse species' responses to different types of disturbances.

The results provide insights in how emulation of natural disturbances can be applied in managed and protected areas to facilitate the species survival and to maintain biodiversity.

Experimental setup

The field experiment is set up in mature pine-dominated boreal forests. The factors and the levels to be studied - fire and tree retention level - are shown on the following design scheme:

FIRE is based on fully factorial design with two factors: fire and tree retention level. Factor "fire" has two levels and "retention" four levels. Each factor combination is replicated three times at the forest stand level. The design applies the principle of BACI, i.e. before-after-control-impact measurements. Study was designed and experimental forests were selected in 1999, key variables were measured before the treatments were applied (year 2000) and then after the treatments.

In total, 24 forest stands are included in the experiment.

All the study areas are located in eastern Finland. The size of each study plot (forest stand, replicate) is 3-5 hectares, corresponding roughly to a typical regeneration harvest size in southern Finland. Experimental forests are located within an area that spans ca. 20x30 km.

Photos illustrating retention levels in burned and unburned forest stands 5 years after the experimental disturbances (photos: Jari Kouki):

Retention 50 m3/ha, burned

Retention 10 m3/ha, burned

Retention 50 m3/ha, unburned

Retention 10 m3/ha, unburned

Sampling and measuring

The ecological characteristics of the study areas have been measured before the treatments in 2000 and after the treatments from 2001 onwards.

The variables measured in each site include:

  • living trees (species composition, volumes)

  • dead trees (species composition, volumes, decay characteristics)

  • herbivory by moose and hare on tree seedlings (2002-)

  • beetles and other invertebrates (species composition)

  • forest pests

  • vascular plants, mosses and ground lichens

  • epiphytic lichens

  • polypore fungi

  • other fungi

  • soil seed bank

  • soil characteristics

  • soil animal community

  • assessment of past fire history with dendrochronology

Sampling scheme

Collecting data

Field work at one of the FIRE experimental sites. Measuring and monitoring covers several ecosystem characteristics and also several taxa (see sampling scheme).


Experimental design and samplings follow before-after-control-impact (BACI) factorial design with the following timing milestones:

  • 1999-2000 selection and establishment of the study areas

  • 2000 inventories before the treatments, using the variables shown above

  • 2000-2001 experimental cuttings (done between November-January)

  • 2001 exprimental burning of the study areas (12 out of 24, all burnings on 27-28 June 2001)

  • 2001-2003 measurement of short-term impacts, using the variables shown above

  • 2004 onwards long-term successional monitoring of forest structure and the biota

  • 2021 long-term monitoring still continues (beetles, polypore fungi, trees)


Funding for the experiment has been provided by

  • Academy of Finland (Centre of Excellence Programme)

  • University of Eastern Finland

  • Natural Resources Institute (Joensuu)

  • Metsähallitus

  • Finnish Forest Industries Federation

  • Ministry of Environment

  • Ministry of Agriculture and Forestry

  • Maj and Tor Nessling Foundation

Participating and collaborating organisations, scientists and students

Experts from the following organisations have been involved in the project:

  • University of Eastern Finland (School of Forest Sciences)

  • University of Eastern Finland (Mekrijärvi Research Station)

  • University of Eastern Finland (Department of Biology)

  • Swedish University of Agricultural Sciences SLU

  • Bavarian National Park, Germany

  • University of Würzburg, Germany

  • Technical University of Münich, Germany

  • University of Tartu, Estonia

  • Natural Resources Institute LUKE (Joensuu Research Station)

  • Kuopio Natural History Museum

  • European Forest Institute EFI

  • Metsähallitus Parks and Wildlife Finland

  • Metsähallitus Forestry Ltd

Publications based on the FIRE experiment

Tatsumi, S., Strengbom, J., Cugunovs, M. & Kouki, J. 2020: Partitioning the colonization and extinction components of beta diversity across disturbance gradients. Ecology, e03138.

Hardenbol, A., den Herder, M. & Kouki, J. 2020: Long-term effects of prescribed burning, tree retention, and browsing on deciduous tree recruitment in European boreal forests. Canadian Journal of Forest Research.

Kouki, J, Salo, K. 2020 Forest disturbances affect functional groups of macrofungi in young successional forests – harvests and fire lead to different fungal assemblages. Forest Ecology and Management 463, 118039

Cugunovs, M., Tuittila, E.-S., Kouki, J., 2020. Proximity to charred logs in burned forests likely affects decomposition processes in the soil.

Rodriguez, A., Pohjoismäki, J.L.O., Kouki, J., 2019. Diversity of forest management promotes parasitoid functional diversity in boreal forests. Biological Conservation 238, 108205.

Suominen, M., Junninen, K., Kouki, J., 2019. Diversity of fungi in harvested forests 10 years after logging and burning: Polypore assemblages on different woody substrates. Forest Ecology and Management 446, 63-70.

Suominen, M., Junninen, K., Heikkala, O., Kouki, J. 2018: Burning harvested sites enhances polypore diversity on stumps and slash. - Forest Ecology and Management 414: 47-53.

Granath, G., Kouki, J., Johnson, S., Heikkala, O., Rodríguez, A., Strengbom, J. 2018: Trade-offs in berry production and biodiversity under prescribed burning and retention regimes in Boreal forests. - Journal of Applied Ecology 55:1658–1667.

Thorn, S., Seibold, S., Heikkala, O., Koivula, M., Venugopal, P., Kouki, J., 2018. New records of Northern bats (Eptesicus nilssonii) in boreal clear cuts emphasize the value of green-tree retention for conservation. - Nyctalus 19: 22-26.

Cugunovs, M., Tuittila, E.-S., Sara-Aho, I., Pekkola, L., Kouki, J., 2017. Recovery of boreal forest soil and tree stand characteristics a century after intensive slash-and-burn cultivation. - Silva Fennica, article id 7723

Rodriguez, A., & Kouki, J. 2017: Disturbance-mediated heterogeneity drives pollinator diversity in boreal managed forest ecosystems. - Ecological Applications 27: 589-602.

Cugunovs, M., Tuittila, E.-S., Mehtätalo, L., Pekkola, L., Sara-Aho, I., & Kouki, J. 2017: Variability and patterns in forest soil and vegetation characteristics after prescribed burning in clear-cuts and restoration burnings. - SIlva Fennica, article id 1718.

Heikkala, O., Martikainen, P., Kouki, J. 2017: Prescribed burning is an effective and quick method to conserve rare pyrophilous forest-dwelling flat bugs. - Insect Conservation and Diversity 10: 32-41.

Eales, J., Haddaway, N.R., Bernes, C., Cooke, S.J., Jonsson, B.G., Kouki, J., & Petrokofsky, G. 2016: What is the effect of prescribed burning in temperate and boreal forest on biodiversity, beyond tree regeneration, pyrophilous and saproxylic species? A systematic review protocol.

Environmental Evidence, 5, 24.

Hämäläinen, A., Hujo, M., Heikkala, O., Junninen, K. & Kouki, J. 2016: Retention tree characteristics have major influence on the post-harvest tree mortality and availability of coarse woody debris in clear-cut areas. - Forest Ecology and Management 369: 66-73.

Heikkala, O., Martikainen, P., Kouki, J. 2016: Decadal effects of emulating natural disturbances in forest management on saproxylic beetle assemblages. - Biological Conservation 194: 39-47.

Heikkala, O., Seibold, S., Koivula, M., Martikainen, P., Müller, J., Thorn, S., Kouki, J. 2016: Retention forestry and prescribed burning result in functionally different saproxylic beetle assemblages than clear-cutting. - Forest Ecology and Management 359: 51-58.

Rodríguez, A., Kouki, J., 2015. Emulating natural disturbance in forest management enhances pollination services for dominant Vaccinium shrubs in boreal pine-dominated forests. - Forest Ecology and Management 350: 1-12. (OPEN ACCESS)

Awarded the Editors' Choice status of Forest Ecology and Management by the Elsevier Editors' Panel.

Suominen, M., Junninen, K., Heikkala, O., Kouki, J., 2015. Combined effects of retention forestry and prescribed burning on polypore fungi. - Journal of Applied Ecology 52: 1001-1008.

Hämäläinen, A., Kouki, J., Lohmus, P., 2015. Potential biodiversity impacts of forest biofuel harvest: lichen assemblages on stumps and slash of Scots pine. Canadian Journal of Forest Research 45: 1239-1247.

Johnson, S., Strengbom, J. & Kouki, J. 2014: Low levels of tree retention do not mitigate the effects of clearcutting on ground vegetation dynamics. - Forest Ecology and Management 330: 67-74.

Heikkala, O., Suominen, M., Junninen, K., Hämäläinen, A. & Kouki, J. 2014: Effects of retention level and fire on retention tree dynamics in boreal forests. - Forest Ecology and Management, in press.

Hämäläinen, A., Kouki, J. & Lohmus, P. 2014: The value of retained Scots pines and their dead wood legacies for lichen diversity in clear-cut forests: the effects of retention level and prescribed burning. - Forest Ecology and Management, in press.

Kouki, J. 2013: Nuoret luonnonmetsät metsien hoidon ja suojelun mallina - Uusia mahdollisuuksia metsäluonnon suojeluun talousmetsissä. - Luonnon Tutkija 117: 4-19.

Kouki, J., Hyvärinen, E., Lappalainen, H., Martikainen, P. & Similä, M. 2012: Landscape contect affects the success of habitat restoration: large-scale colonization patterns of saproxylic and fire-asssociated species in boreal forests. - Diversity and Distributions 18:348-355.

doi: 10.1111/j.1472-4642.2011.00839.x

Lindenmayer, D.B., Franklin, J.F., Lõhmus, A., Baker, S., Bauhus, J., Beese, W., Brodie, A., Kiehl, B., Kouki, J., Martínez Pastur, G., Messier, C., Neyland, M., Palik, B., Sverdrup-Thygeson, A., Volney, J., Wayne, A. & Gustafsson, L. 2012: A major shift to the retention approach for forestry can help resolve some global forest sustainability issues. - Conservation Letters 5:421-431.


Gustafsson, L., Baker, S., Bauhus, J., Beese, W., Brodie, A., Kiehl, B., Kouki, J., Lindenmayer, D.B., Lõhmus, A., Martínez Pastur, G., Messier, C., Neyland, M., Palik, B., Sverdrup-Thygeson, A., Volney, J., Wayne, A. & Franklin, J.F. 2012: Retention Forestry to Maintain Multifunctional Forests: a World Perspective. - BioScience 62: 633-645.

doi: 10.1525/bio.2012.62.7.6

Brumelis, G., Jonsson B.G., Kuuluvainen, T., Kouki, J. & Shorohova, E. 2011: Forest naturalness in northern Europe: perspectives on processes, structures and species diversity - Silva Fennica 45: 807-821.

Gustafsson, L., Kouki, J. & Sverdrup-Thygeson, A, 2010: Tree retention as a conservation measure in clear-cut forests of North Europe: a review of ecological consequences. - Scandinavian Journal of Forest Research 25: 295-308.

doi: 10.1080/02827581.2010.497495

Hyvärinen, E., Kouki, J. & Martikainen, P. 2009:

Prescribed fires and retention trees help to conserve beetle diversity in managed boreal forests despite their transient negative effects on some beetle groups. - Insect Conservation and Diversity 2:93-105.

doi: 10.1111/j.1752-4598.2009.00048.x

den Herder, M., Kouki, J. & Ruusila, V. 2009:

The effects of timber harvest, forest fire, and herbivores on regeneration of deciduous trees in boreal pine-dominated forests. - Canadian Journal of Forest Research 39: 712-722.


Junninen, K., Kouki, J. & Renvall, P. 2008: Restoration of natural legacies of fire in European boreal forests: an experimental approach to the effects on wood-decaying fungi. - Canadian Journal of Forest Research 308: 208-215. doi:10.1139/X07-145

Pitkänen, A., Kouki. J., Viiri, H. & Martikainen, P. 2008: Effects of controlled forest burning and intensity of timber harvesting on the occurrence of pine weevils, Hylobius spp., in regeneration areas. – Forest Ecology and Management 255: 522-529. doi:10.1016/j.foreco.2007.09.024

Martikainen, P., Kouki. J. & Heikkala, O. 2006: The effects of green tree retention and subsequent prescribed burning on ground beetles (Coleoptera: Carabidae) in boreal pine-dominated forests. - Ecography, in press.

Hyvärinen, E., Kouki, J. & Martikainen, P. 2006: Fire and green-tree retention in conservation of red-listed and rare dead-wood dependent beetles in boreal borests. - Conservation Biology, in press.

Pitkänen, A., E. Järvinen, J. Turunen, T Kolström & J. Kouki 2005: Kulotuksen ja maan muokkauksen vaikutus männyn siementen itämiseen ja kylvötaimien varhaiseen eloonjääntiin. Metsätieteen Aikakauskirja 4/2005: 387–397.

Hyvärinen, E, Kouki, J., Martikainen, P. & Lappalainen, H. 2005: Short-term effects of controlled burning and green-tree retention on beetle (Coleoptera) assemblages in managed boreal forests. – Forest Ecology and Management 212:315-332.

Hyvärinen, E., Kouki, J. & Martikainen, P. 2006: A comparison of three trapping methods in surveying forest-dwelling Coleoptera. - European Journal of Entomology, in press.

Martikainen, P., Kouki, J., Heikkala, O., Hyvärinen, E. & Lappalainen, H. 2005: Effects of green tree retention and fire on the crown damage caused by the pine shoot beetles (Tomicus spp.) in pine-dominated timber harvest areas. – Journal of Applied Entomology 130:37-44.

Pitkänen, A., K. Törmänen, J. Kouki, E. Järvinen and H. Viiri 2005: Effects of green tree retention, prescribed burning and soil treatment on pine weevil (Hylobius abietis and H. pinastri) damage of planted Scots pine seedlings. – Agricultural and Forest Entomology 7:319-331.

PhD theses based on the FIRE experiment

Esko Hyvärinen (
PhD completed in 2006):

Green-tree retention and controlled burning in restoration and conservation of beetle diversity in boreal forests

Kaisa Junninen (PhD completed in 2007):

Conservation of polypore diversity in managed forests of boreal Fennoscandia

Samuel Johnson (PhD completed in 2014, SLU, Sweden)

Retention forestry as a conservation measure for boreal forest ground vegetation

Sebastian Seibold (PhD completed in 2015, Technical University of Munich, Germany):

Biodiversity of dead-wood dependent insects – effects of forest management and prospects of conservation

Aino Hämäläinen (PhD completed in 2016):

Retention forestry and intensified biomass harvest: epiphytic lichen assemblages under opposing ecological effects in pine-dominated boreal forests

Osmo Heikkala (
PhD completed in 2016):

Emulation of natural disturbances and the maintenance of biodiversity in managed boreal forests: the effects of prescribed fire and retention forestry on insect assemblages.

Mihails Cugunovs (
PhD completed in 2018):

Impacts of fire in active and passive restorations on boreal forest soils and vegetation

Mai Suominen (
PhD completed in 2018):

Harvested and burned forests as habitats for polypore fungi

Antonio Rodriguez (PhD completed in 2018):

Promoting biodiversity and ecosystem services in managed boreal forests through disturbance-mediated functional heterogeneity.

Kauko Salo (PhD completed in 2019):

The structure of macrofungal assemblages in boreal forests, with particular reference to the effect of fire on Basidiomycota and Ascomycota

Alwin Hardenbol (PhD completed in 2020):

Dynamics of biodiversity-rich deciduous trees and microhabitats in boreal forests

MSc theses based on the FIRE experiment

Jukka Behm (MSc thesis, 2001):

Soil seed-bank composition in areas with varying fire history

Terhi Kaipainen (MSc thesis, 2001):

Past fire frequencies in mature forest stands in eastern Finland

Rauli Perkiö (MSc thesis, 2003):

Fire history and aspen populations in protected old growth forests

Jarkko Laamanen (MSc thesis, 2001):

Mosaic patterns of fire intensity in pine-dominated forests

Katja Sidoroff (MSc thesis, 2002):

Fire as a mortality factor in boreal forest trees

Jaana Turunen (MSc thesis, 2002):

Tree recruitment and the intensity of forest fires

Mervi Hakulinen (MSc thesis, 2002):

Short-term impacts of forest fire on ground vegetation

Tommi Kinnunen (MSc thesis,2004)

The effects of fire on fungal infections of pine saplings

Kaisa Törmänen (MSc thesis, 2003)

The effects of fire on the occurrence of pine weevil damage

Osmo Heikkala (MSc thesis, 2003)

Short-term effects of fire and retention trees on carabid beetles in boreal forests

Jaana Heikkala (MSc thesis, 2003)

Polypore fungi assemblages in state-owned mature forests in eastern Finland

Tuomo Reinikainen (MSc thesis, 2006)

Large mammalian herbivores and early forest succession after fire and clear-cutting

Noora Lankinen (MSc thesis, 2008)

The effect of forest fires and green-tree retention on bark beetles and their associated species

Alain Joseph (MSc thesis, 2010):

The contribution of retention trees to patterns and dynamics of coarse woody debris in pine-dominated boreal forests

Aino Hämäläinen (MSc thesis, 2010):

Effects of fire and timber harvest on small mammal communities

Nicola A K Bakker (MSc thesis 2014):

How do alternative forest management systems impact natural tree regeneration in the European northern boreal forest?

Sabrina Van de Velde (MSc thesis 2015:

The role of prescribed fire and harvest intensity on Cerambycidae beetle diversity in managed Scots pine forests

Laura Pekkola (MSc thesis 2016):

Long-term effects of small-scale spatial variations in fire severity on bilberry (Vaccinium myrtillus L.) growth in the boreal forests of eastern Finland

Lauri Helenius (MSc thesis 2021):

Laser scanning to identify retention trees left in logging area


Hyvärinen, E., Juslén, A., Kemppainen, E., Uddström, A., Liukko, U.-M. (Eds.), 2019. The 2019 Red List of Finnish species. Finnish Environment Institute and Ministry of Environment, Helsinki.

Kouki, J., Junninen, K., Mäkelä, K., Hokkanen, M., Aakala, T., Hallikainen, V., Korhonen, K.T., Kuuluvainen, T., Loiskekoski, M., Mattila, O., Matveinen, K., Punttila, P., Ruokanen, I., Valkonen, S., Virkkala, R., 2018. Forests. In: Kontula, T., Raunio, A. (Eds.), Threatened habitat types in Finland 2018. Red List of habitats. Part I: Results and basis for assessment. Finnish Environment Institute and Ministry of Environment, Hesinki, pp. 171-201.