Rehabilitating boreal forest structure and species composition in Finland through logging, dead wood creation and fire: The EVO experiment I. Vanha-Majamaa a, * , S. Lilja a,b , R. Ryo ¨ma ¨ a,c , J.S. Kotiaho d,e , S. Laaka-Lindberg c , H. Lindberg f , P. Puttonen a , P. Tamminen a , T. Toivanen d , T. Kuuluvainen b a The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FIN-01301 Vantaa, Finland b Department of Forest Ecology, P.O. Box 27, University of Helsinki, 00014 Helsinki, Finland c Lammi Biological Station, University of Helsinki, Finland d Department of Biological and Environmental Science, P.O. Box 35, University of Jyva ¨skyla ¨, 40014 Jyvaskyla, Finland e Natural History Museum, P.O. Box 35, University of Jyva ¨skyla ¨, 40014 Jyvaskyla, Finland f HAMK, University of Applied Sciences, Saarelantie 1, Lammi 16970, Finland Abstract This paper reviews an ongoing, large-scale multidisciplinary experiment designed to study the possibilities of rehabilitating forest structure and species composition through logging, dead wood creation and fire in managed Norway spruce (Picea abies) forests in southern Finland. These forests have been utilized for several centuries with intensive management and clear-cut harvesting, which has been the dominant practice in Finland since World War II. During this era, the forest structure has become relatively even-aged, and the amount of dead wood has been reduced considerably. Simultaneously, due to an effective fire suppression policy, the role of fire in Finnish nature has been almost completely eliminated. One of the key species in biodiversity, aspen (Populus tremula), has also been actively removed from the forests in the past. Forest restoration activities, such as the creation of dead wood and the reintroduction of fire to forest management, have been suggested in conservation and restoration programmes. So far we have studied the immediate effects of restorative actions on forest structure, regeneration, soil nutrient status, understorey and epixylic vegetation, lichens and beetles. In the larger Evo research area we have also studied the population structure of aspen in both protected and managed forests. Our early results show that it is possible, through active forest restoration, i.e. the creation of dead wood and prescribed burning, to rehabilitate boreal forest diversity, even when a significant part of the wood volume is harvested for commercial use. Despite the fact that the immediate effects of fire on many species groups were negative, the long-term effects are expected to be predominantly positive. There is currently a decline in aspen populations in Finnish forests. The absence of large aspens in managed forests and the absence of younger trees/cohorts in conservation areas, combined with high mortality, is a significant threat to aspen-dwelling species. We conclude that studies on active restoration treatments, together with long-term inventories of several species groups, are necessary in order to assess the impacts of varying restoration practices for cost-efficient large-scale applications. # 2007 Published by Elsevier B.V. Keywords: Aspen; Beetles; Bryophytes; Epixylic vegetation; Forest structure; Invertebrates; Lichens; Soil nutrients; Understorey vegetation 1. Introduction In Fennoscandia, forestry-related degradation of natural forest habitats, and a subsequent high number of red-listed species, are well-documented phenomena (e.g. Linder and O ¨ stlund, 1998; Kouki et al., 2001; Rassi et al., 2001). In the forest environment, intensive forest management and the resulting changed forest structure, a lack of deciduous tree species, dead wood and fire are the key elements and main reasons for the decline in biodiversity (Ohlson et al., 1997; Granstro ¨m, 2001; Kouki et al., 2001; Siitonen, 2001; Kuuluvainen et al., 2002; Gandhi et al., 2004; Kouki et al., 2004; Hyva ¨rinen et al., 2005; Jonsson et al., 2005). Dead wood microsites are characteristic to natural stands (Kuuluvainen and Laiho, 2004), and serve as habitats for several species and species groups (Kruys et al., 1999; Uotila, 2004; Laaka-Lindberg et al., 2005). The amount of coarse woody debris (CWD, dead trees larger than 10 cm at DBH) in www.elsevier.com/locate/foreco Forest Ecology and Management 250 (2007) 77–88 * Corresponding author. Tel.: +358 10 2112532; fax: +358 10 2112202. E-mail address: ilkka.vanha-majamaa@metla.fi (I. Vanha-Majamaa). 0378-1127/$ – see front matter # 2007 Published by Elsevier B.V. doi:10.1016/j.foreco.2007.03.012