Research themes
My research is focused on the patterns of biodiversity and the dynamics of the boreal forest ecosystems, with applications in conservation biology. The studies aim at understanding how biodiversity is linked with the ecosystem dynamics and how natural disturbances and forest management affect biodiversity patterns.
Key themes are related to questions on how landscape properties and forest succession differ between managed and natural boreal forests, and how these differences are reflected upon ecosystem characteristics and their species assemblages. The studies aim at facilitating the development of ecologically sound forestry and conservation practises.
Several taxonomic groups are covered, including birds, vascular plants, beetles and polyporous fungi. Most of the studies are empirical. Methodology ranges from long-term descriptive landscape transformation analyses to large-scale experimental studies that focus on local and taxon-specific impacts of forest dynamics and forestry practises.
I work in close collaboration with students, associates and colleagues from several Finnish and international universities and research institutes.
A few highlights of the results
Some of the recent findings (and the related publications) of our research include:
1. Young natural forests have almost disappeared but their value in conserving biodiversity 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.
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.
3. Novel, biodiversity-oriented silvicultural practises with prescribed burnings and retention trees and restoration treatments do not seem to 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, in press.
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, in press.
4. Small and isolated protected areas are unlikely to 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.
Rouvinen, S. & J. Kouki 2002: Spatiotemporal availability of dead wood in protected old-growth forests: a case study from boreal forests in eastern Finland. – Scandinavian Journal of Forest Research 17: 317–329.
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, in press.
5. For saproxylic species, both the quantity and diversity of dead wood is 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.
6. Conservation of forest biodiversity can be increased 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.
Project descriptions
Fire and retention trees in facilitating biodiversity patterns
Linking ecological, economic and social aspects of forestry