1993), where it is most likely involved in plant debris degradation. A survey of insufficiently identified sequences from environmental samples in OICR-9429 emerencia (Ryberg et al. 2009) revealed that Tetracladium actually commonly occurs in soil samples Target Selective Inhibitor Library or associated with plant roots. In our study, Tetracladium was only absent from soil M, the soil with the lowest
clay content (see Inselsbacher et al. 2009) and therefore lowest water holding capacity from all five soils. Similarly, relatively dry soil conditions and consequently good aeration resulted in highest nitrification activities and highest NO 3 − -N/NH 4 + -N ratios in soil M (Inselsbacher et al. 2009). Predicted species richness (Chao2; Chao 1987) for the soils studied here ranged from 20.4 to 51.3, which is in a similar range as found in comparable studies (see Table 1), but substantially lower than fungal richness estimations from studies employing high throughput sequencing (Buee et al. 2009; Fierer et al. 2007). In addition, richness estimation is strongly dependent on the prediction model (Fierer et al. 2007). For
these reasons predicted species richness allows direct comparison of datasets similar in size analysed by identical models, but gives little information about the actual number of species present in a sample. Predicted species richness, diversity and the phylogenetic composition of fungal communities from arable soils did not differ from the Fossariinae grassland soil R (see Table 1), although soil R showed higher levels of microbial biomass and activity compared to the four arable 17-AAG datasheet soils (Inselsbacher et al. 2009). Likewise, vegetation cover at sampling time did, within the limits of our experimental resolution, not substantially influence richness, diversity and phylogenetic composition of soil fungi. This finding is in agreement with data reported by Waldrop et al. (2006) who showed that aboveground plant richness does not directly influence belowground fungal richness. While there does not seem to be a difference in general parameters of fungal communities between arable and grassland soils, the most striking
difference is the obvious absence of SCGI from arable soil, a group of fungi that could be found at high frequencies in grassland soils (soil R and natural grassland field site at the Sourhope Research station (Anderson et al. 2003)). SCGI is an only recently detected subphylum at the base of the Ascomycota with thus far no cultivated members (Porter et al. 2008). Presence in grassland and absence in arable soil could be an indication that SCGI fungi directly depend on a continuous plant cover, which is in good agreement with the list published by Porter et al. (2008) summarising sites where SCGI fungi were found. Although site characteristics ranged from tundra to forest and from tropical to boreal, not a single arable site was included in this listing.