Research themes
Research themes
My research focuses on the patterns of biodiversity and the dynamics of the boreal forest ecosystems. The aim is to understand how forest biodiversity is linked with the ecosystem dynamics and how natural disturbances and forest management affect biodiversity patterns.
Together with students and colleagues, we explore how landscape properties, structures of forest stands and forest succession differ between managed and natural forests, and how these differences are reflected upon ecosystem characteristics and their species assemblages. The studies aim at facilitating ecologically sound forestry and conservation practises.
To obtain generally applicable results, we study several taxonomic groups, including birds, plants, mosses, lichens, beetles and fungi. We focus on species assemblages but also on ecosystem-level properties of forests. The methodology ranges from long-term landscape analyses to large-scale experimental studies.
The work is done in close international collaboration with students, associates and colleagues from several Finnish and international universities and research institutes.
Many studies are conducted in a large-scale field experiment FIRE that we established in 1999 and that has been maintained since then. This research infrastructure is presented here:
Key research findings
Key findings (and publications where they are presented) include:
1. Young natural post-disturbance forests and early successional stages have almost disappeared from Fennoscandia but their value in conserving biodiversity and providing ecosystem services is high
Kouki, J., Löfman, S., Martikainen, P., Rouvinen, S. & Uotila, A. 2001: Forest fragmentation in Fennoscandia: linking habitat requirements of wood-associated threatened species to landscape and habitat changes. – Scandinavian Journal of Forest Research Suppl. 3: 27-37.
Similä, M., J. Kouki, P. Martikainen & A. Uotila 2002: Conservation of the beetles in the boreal forests: the effects of naturalness and forest age on species assemblages. – Biological Conservation 106:19-27.
Junninen, K., Similä, M., Kouki, J. and Kotiranta, H. 2006: Assemblages of wood-inhabiting fungi along the gradients of succession and naturalness in boreal pine-dominated forests in Fennoscandia. - Ecography 29:75-83.
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.
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.
http://dx.doi.org/10.1111/1365-2664.13098
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
https://doi.org/10.1016/j.foreco.2020.118039
2. Deliberate and controlled use of forest fires can significantly contribute to the conservation of biodiversity
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 20:1711-1719.
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 29:659-670.
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.
Uotila, A., Hotanen, J.-P. & Kouki , J. 2005: Succession of understorey vegetation in managed and semi-natural Scots pine forests in eastern Finland and Russian Karelia. – Canadian Journal of Forest Research 35:1422-1441.
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.
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.
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.
3. Although restoration with fire is very effective in promoting biodiversity (see above #2), it is not equally beneficial everywhere. Thus, same conservation measure may have different outcome depending on the properties of surrounding landscape.
Kouki, J., Hyvärinen, E., Lappalainen, H., Martikainen, P. & Similä, M. 2012: Landscape context 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.
4. Novel, biodiversity-oriented silvicultural practises with prescribed burnings and retention trees and restoration treatments do not increase pest damages in pine forests
Martikainen, P., Kouki, J., Heikkala, O., Hyvärinen, E. & Lappalainen, H. 2006: 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., Törmänen, K., Kouki, J., Järvinen, E. & Viiri, H. 2005: Effects of green tree retention, prescribed burning and soil treatment on pine weevil (Hylobius abietis and Hylobius pinastri) damage to planted Scots pine seedlings. – Agricultural and Forest Entomology 7:319-331.
Pitkänen, A., Kouki. J., Viiri, H. & Martikainen, P. 2007: 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.
Komonen, A. & Kouki, J. 2008: Do restoration fellings in protected forests increase the risk of bark beetle damages in adjacent forests? A case study from Fennoscandian boreal forest. – Forest Ecology and Management 255: 3736-3743.
5. Small and isolated protected areas - such as woodland key habitats - are unlikely to fully support viable populations of rare and threatened species
Kouki, J., Arnold, K. & Martikainen, P. 2004: Long-term persistence of aspen and its associated threatened species are endangered in old-growth conservation areas in Finland. – Journal for Nature Conservation 12:41–52
Kouki, J. & Väänänen, A. 2000: Impoverishment of resident old-growth forest bird assemblages along isolation gradient of protected areas in eastern Finland. – Ornis Fennica 77: 145–154.
Junninen, K. & Kouki, J. 2006: Are woodland key habitats hotspots for polypores (Basidiomycetes)? - Scandinavian Journal of Forest Research 21:32-40.
Hokkanen, P., Kouki, J. & Komonen, A. 2008: Nestedness, SLOSS and conservation networks of boreal herb-rich forests. - Applied Vegetation Science 12: 295-303.
Komonen, A. & Kouki, J. 2011: Do woodland key habitats really support the functionality of reserve networks? - Biological Conservation 144:667.
6. For species associated to dead wood, both the quantity and diversity of dead wood are important
Similä. M, Kouki, J. & Martikainen, P. 2003: Saproxylic beetles in managed and seminatural Scots pine forests: quality of dead wood matters. – Forest Ecology and Management 174:365–381.
Junninen, K., Similä, M., Kouki, J. & Kotiranta, H. 2006: Assemblages of wood-inhabiting fungi along the gradients of succession and naturalness in boreal pine-dominated forests in Fennoscandia. - Ecography 29:75-83.
Tikkanen, O-P., Martikainen, P., Hyvärinen, E., Junninen, K. & Kouki, J. 2006:Red-listed boreal forest species of Finland: associations with forest structure, tree species, and decaying wood. - Annales Zoologici Fennici 43:373–383.
Pasanen, H., Junninen, K., Boberg, J., Tatsumi, S., Stenlid, J., Kouki, J. 2018. Life after tree death: Does restored dead wood host different fungal communities to natural woody substrates? Forest Ecology and Management 409, 863-871.
7. Conservation of forest biodiversity can be enhanced cost-efficiently with only marginal economic losses
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 20:1711-1719.
Tikkanen, O-P, Heinonen, T., Kouki, J. & Matero J. 2007: Habitat suitability models of saproxylic red-listed boreal forest species in long-term matrix management: Cost-effective measures for multi-species conservation. – Biological Conservation 14:359-372.
Mönkkönen, M., Reunanen, P., Kotiaho, J.S., Juutinen, A., Tikkanen, O.-P. & Kouki, J. 2011: Cost-effective strategies to conserve boreal forest biodiversity and long-term landscape-level maintenance of habitats. - European Journal of Forest Research 130:717-727.
An in-depth analysis of this subject matter is available in Finnish in (includes summary and captions for figures and tables in English):
Kouki, J. & Tikkanen, O.-P. (eds.) 2007: Uhanalaisten lahopuulajien elinympäristöjen turvaaminen suojelualueilla ja talousmetsissä: Kustannustehokkuus ja ekologiset, ekonomiset sekä sosiaaliset vaikutukset Kitsin seudulla Lieksassa - Conservation of threatened saproxylic species assemblages in eastern Finland: long-term cost-efficient solutions and their ecological, economic and social implications- Suomen Ympäristö - Finnish Environment 24:1-104.
Click link below to download the pdf file: