FIRE project

Fire and retention trees in facilitating biodiversity in boreal forests:

FIre and tree Retention Experiment (FIRE) 

The large-scale field experiment related to forest fire, forest management and the maintenance and restoration of biodiversity in managed and protected forests.

Objectives of the experiment
Experimental setup and response variables
Participating organisations
Publications and theses

Burning one of the study forests on 28th June, 2001. Photo © Jari Kouki.



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 the recent decades.

Protected areas cover only 5-10 % of forests 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 we initiated a large scale field experiment to resolve key issues on maintaining biodiversity in forests. The focus is on comparisons between disturbances caused by natural causes (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 varying 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 and monitoring

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

The size of each study plot (replicate) is 3-5 hectares, corresponding roughly to a typical regeneration cutting size in southern Finland. Each factor combination is replicated three times. Thus, 24 study plots in total are included in the experiment. All the study areas are located in eastern Finland.

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 (species composition)
  • forest pests
  • vascular plants, mosses and ground lichens
  • polypore fungi
  • other fungi
  • soil seed bank
  • soil characteristics
  • soil animal community
  • assessment of past fire history with dendrochronology


The experimental design and samplings follow before-after-control-impact 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, completed 27-28 June)
  • 2001-2003 measurement of short-term impacts, using the variables shown above
  • 2004 onwards long-term successional monitoring of forest structure and the biota
Funding for the experiment is provided by (listed are only the organisations that have already made their grant decisions)
  • 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 Munich, Germany
University of Tartu, Estonia
Natural Resources Institute LUKE (Joensuu Research Station)
Kuopio Natural History Museum
Metsähallitus Parks and Wildlife Finland
Metsähallitus Forestry Ltd

Publications and theses related to the FIRE experiment

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

Unpublished 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


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.