ORIGINAL PAPER Afforestation of abandoned farmland with conifer seedlings inoculated with three ectomycorrhizal fungi—impact on plant performance and ectomycorrhizal community A. Menkis & R. Vasiliauskas & A. F. S. Taylor & J. Stenlid & R. Finlay Received: 24 July 2006 / Accepted: 3 January 2007 / Published online: 3 February 2007 # Springer-Verlag 2007 Abstract The aim of a 3-year study was to investigate whether inoculation of Pinus sylvestris L. and Picea abies (L.) Karst. seedlings with mycorrhizas of Cenococcum geophilum Fr., Piceirhiza bicolorata, and Hebeloma crus- tuliniforme (Bull.) Quel. has any impact on: 1) survival and growth of outplanted seedlings on abandoned agricultural land, and 2) subsequent mycorrhizal community develop- ment. For inoculation, the root system of each plant was wrapped in a filter paper containing mycelium, overlaid with damp peat–sand mixture and wrapped in a paper towel. In total, 8,000 pine and 8,000 spruce seedlings were planted on 4-ha of poor sandy soil in randomized blocks. Already after the first year natural mycorrhizal infections prevailed in the inoculated root systems, and introduced mycorrhizas were seldom found. Yet, the seedlings that had been pre-inoculated with C. geophilum and the P. bicolor- ata during the whole 3-year period showed significantly higher survival and growth as compared to controls. Moreover, the independent colonization of roots by C. geophilum and the P. bicolorata from natural sources was also observed. A diverse mycorrhizal community was detected over two growing seasons in all treatments, showing low impact of inoculation on subsequent fungal community development. A total of 19 additional ectomy- corrhizal morphotypes was observed, which clustered into two well-separated groups, according to host tree species (pine and spruce). In conclusion, the results showed limited ability to increase tree survival and growth, and to manipulate the mycorrhizal community even by extensive pre-inoculations, indicating that fungal community formation in root systems is governed mainly by environmental factors. Keywords Cenococcum . Piceirhiza . Hebeloma . Pinus sylvestris . Picea abies Introduction The establishment and performance of outplanted seedlings has often been reported to depend on ectomycorrhizal (ECM) fungi (Perry et al. 1987; Kropp and Langlois 1990; Stenström et al. 1990; Le Tacon et al. 1994; Pera et al. 1999; Baum et al. 2002; Dunabeitia et al. 2004), which may enhance uptake of water and nutrients (Smith and Read 1997) and lengthen the life and increase the growth of roots (Chilvers and Gust 1982; Wilcox 1996) by protecting them against drought, pathogens, and heavy metal pollution (Chakravarty and Unestam 1985; Colpaert and Vanassche 1992; Morin et al. 1999; Van Tichelen et al. 2001; Ortega et al. 2004). Because of the absence of host trees, a farmland is often deficient in natural ectomycorrhizal inoculum (Hacskaylo 1973), thus mycorrhization of seedling roots at outplanting might be beneficial. However, seedlings used in afforestation are often cultivated as bare root seedlings in forest nurseries and reportedly are only colonized by ECM fungi to a lesser extent (Dunabeitia et al. 2004; Menkis et al. 2005). Consequently, failure in afforestation has been hypothesized to be caused by the absence of mycorrhizas (Bjorkman 1970; Mikola 1970; Marx 1980). One way of overcoming this problem would be preinoculation of seedlings with selected ECM fungi. As this is a highly resource-consuming effort, the seedlings should be inocu- lated with ECM fungi best suited to host tree species and that rapidly colonize their roots, and which are well adapted Mycorrhiza (2007) 17:337–348 DOI 10.1007/s00572-007-0110-0 A. Menkis (*) : R. Vasiliauskas : A. F. S. Taylor : J. Stenlid : R. Finlay Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-750 07 Uppsala, Sweden e-mail: Audrius.Menkis@mykopat.slu.se