Reduced diversity of AM fungi in annually cropped fields of the Canadian prairie
The arbuscular mycorrhizal (AM) fungi are important service providers to agriculture that are impacted by certain cultural practices. We assessed the status of AM fungal resources in the Prairie, from the Grey to the Brown soil zone, through sampling 176 wheat fields, 117 adjacent roadsides and 24 natural areas, at heading. The 18S rRNA gene sequences of AM fungi in soil metagenomic DNA accounted for 15% of all fungal target sequences recorded, and clustered in 122 operational taxonomic units (OTUs), a proxy for species. A few OTUs dominated under each land use type, and these OTUs often dominated under all three types of land use. The AM fungal community was influenced by land use and soil type. The size of the family Claroideoglomeraceae decreased from Black to Brown soils, and from roadside to field soil. On average, about eight OTUs were found in a field or a natural soil as compared to 14 in roadsides, and diversity (Shannon index) was lowest in cropland where the community was very uneven. The diversity and abundance of AM fungi was low in Brown soils. Lower AM fungal abundance and diversity in 2009, the dry year, than in 2010, the wet year, suggests that the proliferation of AM fungi in Brown soils may be limited by water availability. A long history of frequent fallow and wheat monoculture in the Brown soil zone may also explain reduced AM fungal diversity in these dry soils.
arbuscular mycorrhizal fungi
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