ORIGINAL PAPER Mechanical soil disturbance as a determinant of arbuscular mycorrhizal fungal communities in semi-natural grassland Tim Krone Schnoor & Ylva Lekberg & Søren Rosendahl & Pål Axel Olsson Received: 11 March 2010 / Accepted: 15 June 2010 # Springer-Verlag 2010 Abstract While the effect of disturbance on overall abundance and community composition of arbuscular mycor- rhizal (AM) fungi has been researched in agricultural fields, less is known about the impact in semi-natural grasslands. We sampled two AM plant species, Festuca brevipila and Plantago lanceolata, from an ongoing grassland restoration experiment that contained replicated plowed and control plots. The AM fungal community in roots was determined using nested PCR and LSU rDNA primers. We identified 38 phylotypes within the Glomeromycota, of which 29 belonged to Glomus A, six to Glomus B, and three to Diversisporaceae. Only three phylotypes were closely related to known morphospecies. Soil disturbance significantly reduced phylotype richness and changed the AM fungal community composition. Most phylotypes, even closely related ones, showed little or no overlap in their distribution and occurred in either the control or disturbed plots. We found no evidence of host preference in this system, except for one phylotype that preferentially seemed to colonize Festuca. Our results show that disturbance imposed a stronger structuring force for AM fungal communities than did host plants in this semi-natural grassland. Keywords LSU rDNA . Plowing . Calcareous grassland . Phylogenetic networks Introduction Disturbance creates and alters ecosystems, and changes in disturbance intensity are hypothesized to influence species richness (Connell 1978; Huston 1979) and possibly ecosystem functions. Due to this, the impact of disturbance has been studied in many different ecosystems and groups of organisms, albeit with an emphasis on plants. Most land plants are colonized by arbuscular mycorrhizal (AM) fungi, where the fungi can provide the majority of plant required P (Smith et al. 2003) in return for up to 20% of the assimilated carbon (C; Jakobsen and Rosendahl 1990). Due to the ubiquitous nature and functional importance of AM, a better understanding of the effect of disturbance on plant communities will also require a consideration of the fungal partner of the symbiosis. While little is known about the effect of disturbance on AM fungi in natural plant communities, more studies have been conducted in agricultural fields. Plowing and other forms of disturbances have been shown to reduce overall AM fungal abundance (Allison et al. 2005; Kabir 2005; Lekberg and Koide 2005), spore numbers (Galvez et al. 2001; Oehl et al. 2003), and species richness (Antunes et al. 2009). Other studies have indicated no change in overall richness, but a drastic shift in community composition (Hamel et al. 1994; Jansa et al. 2002; Jansa et al. 2003; Violi et al. 2008). These could be due to differences in life history strategies among fungal taxa generated by disparate growth patterns (Hart and Reader 2002) and infective propagules (Klironomos and Hart 2002). For example, Glomus mosseae and Glomus caledonium sporulate readily T. K. Schnoor (*) : P. A. Olsson Plant Ecology and Systematics, Department of Biology, Lund University, The Ecology Building, Sölvegatan 47, 223 62 Lund, Sweden e-mail: tim.krone_schnoor@ekol.lu.se Y. Lekberg : S. Rosendahl Terrestrial Ecology, Department of Biology, University of Copenhagen, Øster Farimagsgade 2D, 1353 København K, Denmark Mycorrhiza DOI 10.1007/s00572-010-0325-3